Improved therapeutic response by distinct timing of multiple heat treatments during interstitial radiation in the Dunning R3327 prostate tumor model

PURPOSE: As a continuation of a previous study showing the efficacy of a single local tumor heat treatment (LTH) in combination with interstitial radiation (IR) in the Dunning tumor system R3327 (subline AT1), we evaluated higher doses and/or lower dose rates with an extended time course of IR treatment, which allowed greater flexibility for LTH applications. METHODS: IR was carried out by the insertion of one removable 192Ir seed into the center of a R3327-AT1 tumor, transplanted s.c. into the distal thigh of Copenhagen rats. LTH (43.5 degrees C, for 35 min) varied from one treatment just before IR to multiple applications beginning at 0 h and repeated every 48 h or 72 h. RESULTS: The Dunning subline R3327-AT1 is a very thermoresistant tumor, which did not reveal any thermal response when heated up to 44.5 degrees C for 35 min. IR alone produced a delay in tumor growth, related to dose and dose rates of 18-53 cGy/h. During longer treatment times, a single LTH just before the IR was no more effective than IR alone. Thermoradiotherapy with multiple LTH treatments given at intervals of between 48 h and 72 h resulted in a clear increase in growth delay. Radiosensitization was highest in all dose-rate groups where LTH was applied every 72 h during a complete course of IR. CONCLUSIONS: These results demonstrate the importance of administering a sequence of multiple applications of LTH during continuous low-dose-rate irradiation and they substantiate our earlier findings, with shorter exposure times, where one LTH given every 72 h appeared to be most efficient in the combined treatment of the Dunning rat prostate tumor R3327-AT1.     

The response of Dunning R3327 prostatic adenocarcinoma to IL-2, histamine and radiation

A syngeneic, androgen-sensitive Dunning R3327 rat prostatic adenocarcinoma was transplanted bilaterally in the flanks of male Copenhagen Fisher rats. Approximately 3 months after implantation, when the tumours had a median volume of 150 mm3, one group of rats was treated with histamine alone (4 mg kg(-1) subcutaneously on week days), another group with human recombinant interleukin 2 (IL-2) alone (425 IU kg(-1) continuous infusion) and a third group with both histamine and IL-2 during 6 weeks. Tumours on one flank were irradiated (6 Gy once daily for 3 days to a total dose of 18 Gy) beginning 1 week after the onset of treatment with histamine and/or IL-2. The contralateral tumour served as the intra-animal control. The tumour volumes were determined weekly. The growth curves showed that all three drug treatments were effective in delaying growth, but when used individually did not cause tumour shrinkage. Radiation was the most effective single agent, but when used alone the shrinkage did not occur until 2 weeks after irradiation. When combined with the drugs, more rapid and extensive growth delay and/or shrinkage was seen. The growth curves showed clear differences between the different treatments. The combination of the three agents was the most effective of all. The most striking difference between radiation alone and radiation plus biotherapy was the time at which a tumour response was detectable. Thus, active biotherapy alone and especially in a combination with histamine and radiotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.     

Induction of enhanced postnatal expression of immunoreactive calbindin-D28k in rat forebrain by the calcium antagonist nimodipine

Male Copenhagen x Fisher F1 rats, transplanted with the androgen-sensitive Dunning R3327 PAP rat prostatic adenocarcinoma, were castrated when tumor volumes were approximately 1300 mm3. The rats were thereafter followed with measurements of tumor volume. Castration stopped tumor growth, but some of the tumors started to regrow after 7-36 weeks. These tumors relapsing from castration treatment were now considered to be androgen-insensitive. In this study, we defined relapse as the time when the tumor volume had increased to 200% of the volume at the time for castration. At this time, the rats were treated either with estradiol-17 beta (E2, 50 micrograms s.c. daily) or vehicle for 8 weeks. After this period, tumor morphology was examined. The tumors in the vehicle-treated group were heterogeneous, and both highly and more dedifferentiated parts were present. The tumor growth rate was correlated to the epithelial cell nuclear size and its variance, and to the mitotic index. In the E2-treated group, tumor growth rate was retarded throughout the treatment period, and dedifferentiated tumor areas were rare. Estrogen treatment resulted in a reduction of nuclear area and mitotic index, a changed nuclear shape, and an increased apoptotic index compared to that in vehicle-treated tumors. By castration, it is possible to induce an alteration of the androgen-sensitive Dunning R3327 PAP tumor phenotype to an androgen-insensitive tumor with an altered morphology. Estradiol-17 beta apparently inhibits not only the growth, but also postpones the castration-induced dedifferentiation of the tumor.     

Growth kinetics and treatment response of the intracerebral rat 9L brain tumor model: a quantitative in vivo study using magnetic resonance imaging

We report the use of magnetic resonance imaging (MRI) for in situ tumor growth rate studies of experimental intracranial 9L tumors. T2-weighted spin-echo coronal magnetic resonance images of rat brains with 9L tumors were obtained every 2 days beginning at 8-11 days postimplantation using a 7 tesla MRI system. Tumors were clearly delineated in the images as a hyperintense region with a relatively well-demarcated border and minimal peritumoral edema. Tumor volumes from individual slices were summed together to yield the total tumor volume. The accuracy of this methodology for volumetric determination was verified by MRI phantom studies. Tumor growth rates determined from sequential MRI measurements of tumor volumes were quantitated in terms of volumetric doubling time. Tumor doubling times were found to range from 50 to 81 h, with an average of 66 +/- 8 h (n = 10). Intracranial 9L tumors were found to grow exponentially over the entire life span of the animal, allowing treated animals to serve as their own controls since the volumetric doubling time could be determined from three to four MRI scans before treatment administration. The intracerebral tumor growth delay following a single injection of 1, 3-bis(2-chloroethyl)-1-nitrosourea (13.3 mg/kg i.p.) allowed for noninvasive determination of in vivo log cell kill. A 2.0 +/- 0.2 (n = 3) log cell kill from 1,3-bis(2-chloroethyl)-1-nitrosourea treatment was found from post-treatment MRI volume measurements. These results demonstrate that MRI provides a powerful and sensitive method for assessing the growth and treatment response of intracranial 9L tumors in the rat.     

Cell kinetics of head and neck cancers

We measured the tumor cell proliferative rate in 26 patients with head and neck cancer, 22 of which were squamous cell carcinomas (SCCs). Patients received sequential infusions of iododeoxyuridine and bromodeoxyuridine, after which the tumor was biopsied and studied. The percentage of labeled cells [labeling index (LI)] in well-differentiated SCCs was 20.4 +/- 2.7% (mean +/- SE) and 23.8 +/- 2.1% in moderately differentiated SCCs (P = 0.135). The LIs of two poorly differentiated SCCs were 39.4 and 55.9%. The LI was 2.5% in a high-grade lymphoepithelioma and 24.8% in a malignant lymphoma. In one well-differentiated and one poorly differentiated mucoepidermoid tumor, the LIs were 3.0% and 29.1%, respectively. S-phase duration time measurements ranged from 5.1-21.5 h (12.8 +/- 1.5). The calculated potential doubling times ranged from 18.8-84.5 h (47.3 +/- 6.7). The duration of G2 was between 90 and 180 min. To track the fate of labeled cells, in four patients a repeat biopsy was obtained 7-14 days after the iododeoxyuridine/bromodeoxyuridine infusion. These patients did not receive treatment between the biopsies. Due to the dilution of the label, most labeled cells in the second biopsy demonstrated a "fragmented" pattern resulting from repeated cell divisions. In two patients, however, 25% of cells in the second biopsy had undiluted label, suggesting that these cells had not divided after incorporating iododeoxyuridine/bromodeoxyuridine. On Day 7 labeled cells migrated to keratinized parts of tumors and to necrotic foci. Thus, the arrest of cell cycle transition, tumor cell differentiation, and cell death may be major routes of tumor cell loss from the proliferative compartment. This may explain the difference between very short potential doubling times and the actual rate of tumor growth.     

Preclinical assessment of hypoxic marker specificity and sensitivity

PURPOSE: In the search for a sensitive, accurate, and noninvasive technique for quantifying human tumor hypoxia, our laboratory has synthesized several potential radiodiagnostic agents. The purpose of this study was to assess and compare the hypoxic marking properties of both radioiodinated and Tc-99m labeled markers in appropriate test systems which can predict for in vivo activity. MATERIALS AND METHODS: Preclinical assessment of hypoxic marker specificity and sensitivity employed three laboratory assays with tumor cells in vitro and in vivo. Radiolabeled marker uptake and/or binding to whole EMT-6 tumor cells under extremely hypoxic and aerobic conditions was measured and their ratio defined hypoxia-specific factor (HSF). Marker specificity to hypoxic tumor tissue was estimated from its selective avidity to two rodent tumors in vivo, whose radiobiologic hypoxic fractions (HF) had been measured. The ratios of % injected dose/gram (%ID/g) of marker at various times in EMT-6 tumor tissue relative to that in the blood and muscle of scid mice were used to quantify hypoxia-specific activity. This tumor in this host exhibited an average radiobiologic HF of approximately 35%. As well, nuclear medicine images were acquired from R3327-AT (HF approximately =15%) and R3327-H (no measurable HF) prostate carcinomas growing in rats to distinguish between marker avidity due to hypoxia versus perfusion. RESULTS: The HSF for FC-103 and other iodinated markers were higher (5-40) than those for FC-306 and other Tc-99m labeled markers. The latter did not show hypoxia-specific uptake into cells in vitro. Qualitative differences were observed in the biodistribution and clearance kinetics of the iodinated azomycin nucleosides relative to the technetium chelates. The largest tumor/blood (T/B) and tumor/muscle (T/M) ratios were observed for compounds of the azomycin nucleoside class in EMT-6 tumor-bearing scid mice. These markers also showed a 3-4 x higher uptake into R3327-AT tumors relative to the well-perfused R3327-H tumors. While both FC-306 and CERETEC rapidly distributed at unique concentrations to different tissues, their avidity to EMT-6 and R3327-AT tumors did not correlate with tumor HF. CONCLUSIONS: The halogenated azomycin nucleosides with the lowest lipid/water partition coefficient values were found to yield the optimal hypoxia-specific signal in these animal tumors. Our Tc-99m-labeled azomycin chelates showed little or no hypoxia-specific uptake and had in vivo biodistribution and clearance kinetics similar to those of CERETEC, a perfusion agent with no known hypoxic binding activity.     

Establishment of a highly differentiated thyroid cancer cell line of Hürthle cell origin

Hürthle cell carcinomas (HCC) of the thyroid are a variant of follicular thyroid tumors. In contrast to follicular thyroid carcinoma, HCC rarely take up radioiodine and frequently metastasize to the lymph nodes. Histologically they are indistinguishable from Hürthle cell adenomas except for evidence of invasion and metastasis. How these carcinomas develop and why they behave differently than other follicular tumors is not known. Although some differentiated thyroid cancer cell lines exist, none are from Hürthle cell tumors. We have established a well-differentiated thyroid cancer cell line from a metastasis of a HCC, designated XTC.UC1. In vitro, XTC cells display epitheloid morphology, grow with a population doubling time of 4.3 +/- 0.3 days, migrate, and invade through reconstituted basement membranes. The cells are immunoreactive for and release thyroglobulin, respond to thyrotropin (TSH) with increase of intracellular cyclic adenosine monophosphate (cAMP), proliferation, and invasion of reconstituted basement membrane, thus exhibiting characteristics of well-differentiated thyroid carcinoma. In vivo, xenografted XTC cells grow with a doubling time of 9.8 +/- 0.8 days. Tumors spontaneously metastasize to the lymph nodes and less frequently to the lungs and the liver. The cells retained their differentiated function in vivo as assessed by human thyroglobulin (hTG) secretion and immunohistochemistry. This is a first report of the establishment of a unique, highly differentiated thyroid carcinoma cell line derived from an HCC. Based on the ability to invade through reconstituted basement membrane in vitro and the potential to metastasize in vivo, this cell line may provide a unique model to study invasion and metastazation of well-differentiated thyroid cancer.     

Modification of cytochrome P-450 apoenzyme during its oxidative self-inactivation in a reconstituted mono-oxygenase system

Determination of the doubling time for a population of cells can involve tedious calculations. We have developed computer software for MS-DOS microcomputers to expedite the analysis of tumor cell growth in vitro and in vivo. This program, DOUBLE-TIME, assists in the collection of cell numbers into a database and calculates the doubling time for a population of cells from the plot of cell growth over time. For experiments where tumor mass is measured in vivo, the software collects measurements of tumor size, calculates tumor volume (mass), generates growth curves for tumor volume change over time, and determines the doubling time of the tumor and the mean for multiple tumors. DOUBLE-TIME plots both total and viable cell numbers over time, calculates standard error of the doubling time, and the doubling time for a selected portion of a growth curve. This software also automates the cell counting process with a software-generated cell counter that allows cell counts to be tallied directly into the computer via a mouse.     

Ultrasonic hyperthermia and drugs as therapy for human tumor xenografts

Ultrasonic energy can generate controlled, local hyperthermia (42 degrees C--43 degrees C), and ultrasonic hyperthermia results in increased cytotoxicity of chemotherapeutic drugs for the treatment of cancer. Human breast (MX-1) and lung (LX-1) tumors implanted subcutaneously in athymic nude mice were treated with a single application of ultrasonic (670 kHz, peak intensity of 5 watts/cm2) hyperthermia (43.0 degrees C +/- 0.5 degrees C) for 30 minutes in combination with suboptimal doses of cyclophosphamide, melphalan, or procarbazine. Delays in the tumor growth rate and temporary tumor regression were observed. Comparison of the tumor growth rate with single modalities, ie, drug or hyperthermia alone, shows evidence of synergistic effects of the combination of ultrasonic hyperthermia and melphalan on MX-1 and of hyperthermia and procarbazine on LX-1 tumors.     

Epinephrine or peplomycin combined with hyperthermia in irradiated Lewis lung carcinoma: effects on tumor growth, skin reaction, and lung metastasis

Although hyperthermia potentiates the effect of radiation, the combined effect decreases as the time between irradiation and hyperthermia increases. The purpose of this study was to prevent the rapid loss of efficacy by the local injection of epinephrine or peplomycin(PEP), two agents known as hyperthermic potentiators. In this study, Lewis lung carcinoma implanted in the foot of BDF1 mice was used for the assessment of tumor growth, skin reactions, and lung metastasis. The tumors were irradiated, then warmed in a water bath for 45 min. The retarding effects of hyperthermia on tumor growth and skin reactions were lost 2 days after irradiation. However, when PEP or epinephrine was injected before hyperthermia, tumor growth was distinctly delayed. The effect of epinephrine was greater than PEP and still showed enhancement 8 days after irradiation. For skin reactions, no significant enhancing effect was observed. Lung metastasis was significantly inhibited by the addition of epinephrine either 0 or 2 days after irradiation. In conclusion, the local administration of epinephrine combined with hyperthermia significantly retarded tumor growth without an increase in skin reactions or lung metastases. Possible mechanism underlying this phenomenon was discussed.     

Combined treatment of inoperable carcinomas of the uterine cervix with radiotherapy and regional hyperthermia. Results of a phase II trial

AIM: The disappointing results for inoperable, advanced tumors of the uterine cervix after conventional radiotherapy alone necessitates improving of radiation therapy. Simultaneous chemotherapy or altered radiation fractionation, such as accelerated regimen, increase acute toxicity and treatment is often difficult to deliver in the planned manner. The purpose of this phase II study was to investigate the toxicity and effectiveness of a combined approach with radiotherapy and regional hyperthermia. PATIENTS AND METHODS: From January 1994 to October 1995 18 patients with advanced carcinomas of the uterine cervix were treated in combination with radiotherapy and hyperthermia. The patients were treated with 6 to 20 MV photons delivered by a linear accelerator in a 4-field-box technique to a total dose of 50.4 Gy in 28 fractions. In the first and fourth week 2 regional hyperthermia treatments were each applied with the Sigma-60 applicator from a BSD-2000 unit. After this a boost to the primary tumor was given with high-dose-rate iridium-192 brachytherapy by an afterloading technique with 4 x 5 Gy at point A to a total of 20 Gy and for the involved parametrium anterioposterior-posterioanterior to 9 Gy in 5 fractions. RESULTS: The acute toxicity was low and similar to an external radiotherapy alone treatment. No Grade III/IV acute toxicity was found. The median age was 47 years (range 34 to 67 years). In 16 of 18 patients a rapid tumor regression was observed during combined thermo-radiotherapy, which allowed the use of intracavitary high-dose-rate brachytherapy in these cases. Complete and partial remission were observed in 13 and 4 cases, respectively. One patient did not respond to the treatment. The median follow-up was 24 months (range 17 to 36 months). The local tumor control rate was 48% at 2 years. Median T20, T50 and T90 values were 41.7 degrees C (range 40.3 to 43.2 degrees C), 41.1 degrees C (range 39.2 to 42.5 degrees C) and 39.9 degrees C (range 37.7 to 41.9 degrees C), respectively. Cumulative minutes of T90 > 40 degrees C (Cum40T90) and cumulative minutes, which were isoeffective to 43 degrees C, were calculated (CEM43T90, CEM43T50, CEM43T20). CEM43T90 was found to be a significant parameter in terms of local tumor control for the 4 hyperthermia treatments (p = 0.019). CONCLUSIONS: This treatment modality has proved to be feasible and well tolerable. The rapid tumor shrinkage in the combined approach of radiotherapy with hyperthermia before beginning brachytherapy seems to be a good prerequisite for improving of the disappointing results in cure of advanced cancer of the uterine cervix.     

Effect of S9788 on the efficiency of doxorubicin in vivo and in vitro in medullary thyroid carcinoma xenograft

In medullary carcinoma of the thyroid (MTC), drug resistance remains the major obstacle to effective chemotherapy. In this work, we studied the effect of S9788 on doxorubicin (DOX) efficiency in a MTC cell line (TT cells) injected in nude mice. After two passages, TT cells were injected in 40 nude mice divided into four groups [controls and groups receiving DOX alone (10 mg/kg), S9788 alone (50 mg/kg) or both DOX + S9788]. The weight of the mice, tumoral volume (TV), doubling time (DT) of the tumor and survival time of mice were evaluated in each group. In addition, the efficiency of DOX with or without S9788 was assessed by the inhibition of tumoral growth and specific growth delay. In vitro, glycoprotein P 170 (P-gp) was detected on tissular sections and on tumoral cells by immunocytochemistry or flow cytometry with several monoclonal antibodies: JSB1, MRK 16, C219 and UIC2. In vivo the weight of the mice decreased slightly with DOX and dropped dramatically with DOX + S9788. The DT of the tumors increased with DOX over controls (22.5 +/- 8.5/12.7 +/- 3.9 days) and showed a higher value with DOX + S9788 (29.2 +/- 11.4 days). Inhibition of tumoral growth, 89% with DOX, fell to 47.6% with DOX + S9788. Specific growth delay increased with the double treatment (130 versus 75% with DOX alone). In vitro, P-gp was not detected on tissular sections and cells whatever the method and the antibody used. In conclusion, S9788 potentiates the efficiency of DOX treatment in vivo. The absence of P-gp may result from the absence of translation of the MDR1 gene. The reversal effect of S9788 may involve another resistance mechanism such as the MDR Sister of MRP.     

Phase II study on preoperative radio-chemo-thermotherapy in locally advanced rectal carcinoma

BACKGROUND: Recent studies show that preoperative radio-chemotherapy can increase resectability and local control of locally advanced rectal carcinomas. Additional regional hyperthermia might increase remission rates and tumor response. We therefore tested regional hyperthermia together with radio-chemotherapy in a phase-II study on locally advanced rectal carcinomas. PATIENTS AND METHODS: Thirty-seven patients with primary advanced stage uT3/T4 rectal carcinomas were treated with preoperative radio-chemo-thermo-therapy. The initial tumor depth was determined using endosonography, CT, and MRI. Radiotherapy was carried out in prone position (on a belly board) using standard techniques, with 5 x 1.8 Gy per week up to 45 Gy at the reference point. 5-Fluorouracil (300 to 500 mg/m2) was administered with low doses of leucovorin (50 mg) on days 1 to 5 and 22 to 28. The patients were treated with regional hyperthermia each week prior to radiotherapy and simultaneously with chemotherapy, using the Sigma 60 ring from the BSD-2000 system. Temperature/position curves and temperature/time curves were recorded in endocavitary (endorectal) catheters in tumor contact and as well in bladder and vagina. Following endosonographic restaging, the operation was carried out 4 to 6 weeks after the end of preoperative therapy and adjuvant chemotherapy continued in four cycles. In cases where tumors were non-resectable, a boost up to 64 Gy was aimed. RESULTS: Thirty-one of the 37 patients (84%) with primary carcinoma proved locally R0-resectable. In addition we had 1 R1-resection (3%) and 5 non-resectable tumors (13%). Among the resected tumors, 53% experienced a reduction of depth infiltration from the initial endosonographic stage during preoperative therapy. The actuarial survival rate after 4 years is 65% (free of progression 57%). The actuarial 4-year survival rate was particularly favorable for the group of responders. Overall, the preoperative multimodal therapy was well tolerated, and premature termination was only necessary in 1 case (3%). Grade III/IV toxicities in the intestine and skin were reduced as far as possible by field blockings and cooling of the perineal region. They occurred only in 5/37 patients (13%) at the intestine and in 6/37 patients (16%) at the skin. The thermal data were subjected to a statistical analysis. The quality of temperature distribution (T90, cum min T90 > or = 40.5 degrees C) depends on the power level and relative power density. The response (reduction of tumor size or depth infiltration) correlated significantly with quality parameters of the temperature distributions. This dependency is found as a trend for progression-free survival, too. CONCLUSIONS: Preoperative radio-chemo-thermo-therapy proved to be practical and effective, with encouraging remission rates and excellent local control rates. For this reason, a phase-III study to test regional hyperthermia has been initiated. At the same time, certain technical improvements are still under development for regional hyperthermia.     

Local hyperthermia and SR 4233 enhance the antitumor effects of radioimmunotherapy in nude mice with human colonic adenocarcinoma xenografts

Local hyperthermia and the hypoxic cytotoxin SR 4233 were administered to nude mice with 693 +/- 47 mm3 (mean +/- SE) s.c. HCT-8 human colonic adenocarcinoma xenografts in an attempt to enhance the antitumor effects of radioimmunotherapy. Biodistribution studies revealed preferential binding of NR-Lu-10, a murine monoclonal antibody, to the tumors compared with an isotype-matched control antibody, CCOO16-3.A single injection of 25 microCi 90Y-NR-Lu-10 significantly inhibited tumor growth (control versus 90Y-NR-Lu-10: P = 0.048). The administration of hyperthermia at 41.5 degrees C for 1 h immediately following the injection of 111In-labeled NR-Lu-10 up-regulated tumor-associated antigen expression and increased antibody uptake in the tumors by 73% (P = 0.001) without significantly affecting antibody uptake in normal tissues. However, the heat treatment did not produce a more homogeneous distribution of the antibodies in the tumors and did not significantly enhance the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.07). The administration of local hyperthermia at 43.0 degrees C for 1 h, on the other hand, had direct cytotoxic effects (P = 0.03) and enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.01). SR 4233 also enhanced the tumor growth delay produced by 90Y-NR-Lu-10 (P = 0.03). The greatest antitumor effects were observed when both hyperthermia at 43.0 degrees C and SR 4233 were administered in combination with 90Y-NR-Lu-10 (P = 0.002). No toxicity was produced by the local hyperthermia, and the only toxicities produced by 90Y-NR-Lu-10 and SR 4233 were neutropenia and weight loss.     

Monitoring early response of experimental brain tumors to therapy using diffusion magnetic resonance imaging

Quantitative magnetic resonance imaging was performed to evaluate water diffusion and relaxation times, T1 and T2, as potential therapeutic response indicators for brain tumors using the intracranial 9L brain tumor model. Measurements were localized to a column that intersected tumor and contralateral brain and were repeated at 2-day intervals before and following a single injection of 1,3-bis(2-chloroethyl)-1-nitrosourea (13.3 mg/kg). Tumor growth was measured using T2-weighted magnetic resonance imaging to determine the volumetric tumor doubling time (Td) before (Td = 64 +/- 13 h, mean +/- SD, n = 16) and after (Td = 75 +/- 9 h, n = 4) treatment during exponential regrowth. Apparent diffusion coefficient of untreated tumors was independent of tumor volume or growth time, whereas relaxation times increased during early tumor growth. Diffusion displayed the strongest treatment effect and increased before tumor regression by 55% 6-8 days following treatment. Changes in relaxation times were also significant with increases of 16% for T1 and 27% for T2. Diffusion and relaxation times returned to pretreatment levels by 12 days after treatment. Histological examination supports the model that the observed increase in diffusion reflects an increase of extracellular space following treatment. Furthermore, the subsequent apparent diffusion coefficient decrease is a result of viable tumor cells that repopulate this space at a rate dependent on the surviving tumor cell fraction and recurrent tumor doubling time. Serial tumor volume measurements allowed determination of log cell kill of 1.0 +/- 0.3 (n = 4). These results suggest that diffusion measurements are sensitive to therapy-induced changes in cellular structure and may provide an early noninvasive indicator of treatment efficacy.     

Modifying psychotropic drug prescription patterns: a follow-up survey

Blood flow to the rat ventral prostate (VP), dorsolateral prostate (DP), and Dunning R3327 prostatic tumors was measured at different times up to 7 days after castration, using the microsphere method. In the VP organ weight was decreased from day 3 onwards. Blood flow was, however, already significantly decreased from day 1. The reduced blood flow in VP in 1-3 and 7-day castrated animals could be reversed by testosterone treatment. Organ weight was slightly decreased but blood flow was unaffected by castration in DP. Castration left Dunning tumor volume and blood flow unaffected. Using immunohistochemistry, androgen receptors were observed in epithelial and stromal cells in VP, DP and Dunning tumors, but not in blood vessels. Castration is known to induce apoptosis in the VP, but not in the DP or in Dunning tumors. This suggests that a reduction in blood flow might be an important component for the castration-induced involution and apoptosis in prostatic tissue. The reason why castration reduces blood flow only in the VP, and not in the DP or Dunning tumor is unknown.     

Potentiation of the antitumor effect of ionizing radiation by brief concomitant exposures to angiostatin

Angiostatin, a proteolytic fragment of plasminogen, inhibits the growth of primary and metastatic tumors by suppressing angiogenesis. When used in combination with ionizing radiation (IR), angiostatin demonstrates potent antitumor synergism, largely caused by inhibition of the tumor microvasculature. We report here the temporal interaction of angiostatin and IR in Lewis lung carcinoma (LLC) tumors growing in the hind limbs of syngeneic mice. Tumors with an initial mean volume of 510 +/- 151 mm3 were treated with IR alone (20 Gy x 2 doses on days 0 and 1), angiostatin alone (25 mg/kg/day divided twice daily) on days 0 through 13, or a combination of the two as follows: (a) IR plus angiostatin (days 0 through 13); (b) IR plus angiostatin (days 0 and 1); and (c) IR followed by angiostatin beginning on the day after IR completion and given daily thereafter (days 2 through 13). By day 14, tumors in untreated control mice had grown to 6110 +/- 582 mm3, whereas in mice treated with: (a) IR alone, tumors had grown to 2854 +/- 338 mm3 (P < 0.05 compared with untreated controls); and (b) angiostatin alone, tumors had grown to 3666 +/- 453 mm3 (P < 0.05 compared with untreated controls). In combined-treatment groups, in mice treated with: (a) IR plus longer-course angiostatin, tumors reached 2022 +/- 282 mm3 (P = 0.036 compared with IR alone); (b) IR followed by angiostatin, tumors reached 2677 +/- 469 mm3 (P > 0.05 compared with IR alone); and (c) IR plus short-course angiostatin, tumors reached 1032 +/- 78 mm3 (P < 0.001 compared with IR alone). These findings demonstrate that the efficacy of experimental radiation therapy is potentiated by brief concomitant exposure of the tumor vasculature to angiostatin.     

Accelerated repopulation during fractionated irradiation of a murine ovarian carcinoma: downregulation of apoptosis as a possible mechanism

PURPOSE: To test whether accelerated tumor clonogen repopulation occurs during continuous fractionated radiotherapy of a slow-growing mouse ovarian tumor, and if so whether the accelerated rate of repopulation is predicted by the pretreatment potential doubling time, and whether changes in apoptotic response are a possible mechanism for this change. METHODS AND MATERIALS: The rate of clonogen production during fractionated radiotherapy was followed using the tumor-control assay, with an independent determination of the sensitivity to repeated dose fractions in vivo in the absence of repopulation. The pretreatment potential doubling time was measured by bromodeoxyuridine (BrdUrd) labeling and fluorescence measurements. The apoptotic and mitotic indices at various times during treatment were scored histologically. RESULTS: The slow-growing (pretreatment volume doubling time 6 days) ovarian tumor OCA responds to daily irradiation with 6 Gy under hypoxia by negligible tumor clonogen production in the first few days, followed by a change at about 9 days to accelerated repopulation, after which the effective clonogen doubling time Tclon was about 2 days, near the pretreatment Tpot of 1.7 days. Alternative interpretations of the data, such as a change in radiosensitivity vs. a change in the repopulation rate or acceleration at 3 days as opposed to 9 days, were shown to be unlikely. This change was accompanied by a reduced apoptotic response (measured morphometrically). CONCLUSIONS: When sensitivity to fractionated doses has been corrected for in vivo, this slow-growing mouse tumor exhibits a change to accelerated clonogen production during a continuous radiotherapy regimen that is accompanied or preceded by a reduced histologic apoptotic response. Tclon during accelerated repopulation was slightly longer than the pretreatment Tpot.     

Detection of aneurysm in subarachnoid hemorrhage--CT angiography vs. digital subtraction angiography

The purpose of this study was to investigate the feasibility and the efficacy of administering tirapazamine by a slow-releasing polymer disc that was implanted interstitially into a U251 (human glioblastoma multiforme) tumor grown in nude mice. Tumor-bearing animals, with a tumor nodule 0.8 cm3 in size, were distributed to groups receiving combinations of empty or drug-containing polymer implants in the tumor or contralateral leg, intraperitoneal (i.p.) drug, and/or irradiation. The drug (i.p.) alone (14 mg/kg x6) or in combination with tumor drug implant (2 mg) did not significantly increase the tumor volume doubling time compared to that of control animals. Given with 12 Gy of irradiation in twice a day 2-Gy fractions, combined i.p. drug and tumor drug implant significantly delayed tumor growth compared to irradiation alone, which was not achieved with either drug treatment alone added to irradiation. Toxicity, as manifested by transient weight loss, was primarily seen in animals receiving radiation and i.p. tirapazamine. These results indicated that a slow-releasing tirapazamine disc can be produced and the addition of an interstitially implanted tirapazamine disc further increased the effectiveness of i.p. tirapazamine.     

Proliferative activity of gastric cancer assessed by immunostaining for proliferating cell nuclear antigen

The growth activity of 107 gastric carcinomas was assessed by immunohistochemical staining for formalin-fixed, paraffin-embedded tissue with a monoclonal antibody against proliferating cell nuclear antigen (PCNA). When the tumor doubling times (Tds) of 10 patients were estimated from the serum levels of carcinoembryonic antigen and carbohydrate antigen 19-9, there was an inverse correlation between the Tds and PCNA labeling index (LI) at P = 0.055. Flow-cytometric analysis was carried out by double staining for PCNA and DNA using fresh materials from 14 patients. The PCNA-positive cell fraction revealed by flow cytometry showed a good linear correlation with PCNA LI in routinely stained tissue. The LI of well-differentiated adenocarcinoma was significantly higher than that of the poorly differentiated type. When the LI was analyzed in well- or poorly differentiated adenocarcinoma, the value was significantly higher in the well-differentiated type with hepatic metastasis and in the poorly differentiated type with lymph node metastasis.