Melanoma of unknown primary site: presentation, treatment, and prognosis--a single institution study. University of Pennsylvania Pigmented Lesion Study Group

BACKGROUND: A retrospective analysis of 40 patients diagnosed with melanoma of unknown primary site (MUP) was undertaken to analyze the etiology and clinical behavior of this presentation. METHODS: The patient records were located by a computer search of the Pigmented Lesion Clinic data base at the University of Pennsylvania. With the Cox proportional hazards model, the survival of the MUP patients with lymph node presentation was compared with that of patients with lymph node disease and a known concurrent primary melanoma. RESULTS: Sixty-five percent of the patients presented with lymph node metastasis only, 28% presented with visceral lesions, and 8% presented with subcutaneous nodules. The prevalence of dysplastic nevi was 22.5%. The overall 4-year survival rate for the 40 MUP patients was 55% +/- 9%. The 4-year survival (57% +/- 12%) of patients with lymph node presentation was compared with that of patients presenting with lymph node disease and a known concurrent primary melanoma (19 +/- 6%). Survival was significantly different between the groups (P = 0.008). This survival difference remained significant (P = 0.02) even after adjustments for number of positive lymph nodes, year of diagnosis, and age at diagnosis. CONCLUSIONS: This analysis revealed that MUP patients with lymph node metastasis survived significantly longer than patients diagnosed with lymph node metastasis concurrent with a known cutaneous primary melanoma. The prevalence of dysplastic nevi in the MUP patient series was intermediate between that reported among primary melanoma patients and that reported among population controls, suggesting the likelihood of a primary cutaneous origin for the metastatic melanoma.     

Management of cutaneous melanoma M0: state of the art and trends

This article reviews the epidemiology, diagnosis and treatment of cutaneous melanoma, including the most recent developments. The combination of positive family history, fair complexion, number of nevi, exposure to sun and/or chromosomal alterations seem to be implicated in the pathogenesis of cutaneous melanoma. Melanomas can be classified according to their growth patterns, and tumour microstaging is of straightforward predictive value for survival and risk of metastasis, although new factors are also being investigated. As yet, surgical excision is the only effective treatment available for primary tumours, resection margins varying according to tumour thickness. Elective node dissection is, however, no longer advocated for melanomas thinner than 1.5 mm, and there is disagreement as to its role for thicker lesions. In contrast, selective node dissection at the time of definitive surgery is becoming more widely accepted, with regional node dissection being restricted to positive cases. Therapeutic dissection is required for lymph node involvement, the most common pattern of recurrence from melanoma, which affects nearly 30% of all patients. Complete remission rates from isolated limb perfusion, which has been employed in patients with multiple recurrences or in-transit metastases, range from 40 to 90%, depending on drugs and techniques used in different series; the best responses so far have been obtained with tumour necrosis factor in combination with melphalan. Patients with thick lesions (> 4 mm) or lymph node metastases have a high risk of micrometastases that would warrant adjuvant therapy. The only agent found to affect survival is interferon alpha-2.     

Early metastases in regional lymph nodes and prognosis of malignant melanoma. Histological and clinical examinations in 104 lymphadenectomized patients

In 104 malignant melanoma patients who underwent lymphadenectomy (67 females, 37 males), correlations were studied between histologically diagnosed lymph node metastasis, the type of malignant melanoma and the depth of invasion according to Clark, as well as other parameters. In 35.6% of the patients, metastases of the primary tumor were found in one or several regional lymph nodes. In about one third of the patients, the clinical and histological lymph node findings were proven to diverge. The female:male ratio of generally about 2:1 shifted to 1:1 in the group of patients with lymph node metastasis, i.e. cases with lymph node metastasis were found significantly increased in the male sex, and also, when primary tumors were localized on the trunk. A prognostic correlation between the two parameters, sex and localization, is suggested by the high incidence of histologicallly diagnosed metastases in 1 or 2 lymph node regions, when malignant melanomas were localized on the trunk in males. As to the types and the micro-stages of primary tumors, the number of cases collected until now does not permit establishing clear correlations with the incidence of lymph node involvement. Calculating the 5-year-survival rates for patients with and without lymph node metastasis according to the "actuarial method", we found the prognosis to depend largely on the presence or absence of lymph node involvement, even at a time as early as at primary tumor excision. Our results support the indication for prophylactic lymphadenectomy in malignant melanoma, provided the primary tumor has reached or surpassed the micro-stage 3.     

Malignant mucosal melanoma of the head and neck: review of the literature and report of 14 patients

BACKGROUND: Fortunately, primary malignant mucosal melanoma of the head and neck is a rare entity. A paucity of data elucidating the predictive factors as well as the unpredictable and aggressive biologic behavior of mucosal melanoma compound the vexing clinical situation. This review summarizes what the literature reveals about the epidemiology, patient survival, patterns of local recurrence, and local and distant metastasis of the disease. Over 1000 patients with this disease have been reported. Survivals at 5 and 10 years is 17% and 5%, respectively. Approximately 19% of patients present with lymph node metastasis and another 16% develop lymph node metastases after treatment, whereas 10% present with distant metastasis. Local metastasis does not affect survival; this is in sharp contrast with skin melanoma. Over 50% of patients experience local treatment failure, and salvage treatment is effective in only 25% of these cases. Local failure is the harbinger of distant metastases. Patients with nasal mucosal melanoma have a 31% 5-year survival rate, whereas sinus melanoma patients fare poorly, with a 0% rate of 5-year survival. METHODS: The authors conducted a retrospective review of 14 patients with characteristics similar to those in the literature in terms of outcome. RESULTS: The 5-year survival rate for these patients was 14%. Whole-body positron emission tomography was performed on 3 patients to detect metastatic disease. The patterns of local recurrence, distant metastasis, and survival for these patients were compared with the same data for patients described in the literature. CONCLUSIONS: Surgery appears to have the greatest efficacy in the management of mucosal melanoma, although radiation therapy may play an increasingly important role in the future.     

The accuracy of predicting lymph nodes metastases in malignant melanoma by clinical examination and microstaging

Since 1971, a prospective treatment regimen for primary cutaneous malignant melanoma performed by a single clinician has revealed the following early observations: 1) A significantly higher number of females with level II disease; 2) No recurrences or metastases to date in 29 patients with level II lesions treated by appropriate surgery; 3) The apparent clinical predictability of lymph node metastases in the group microstaged at level III. 4) An inability to predict lymph node metastases (or their delayed development) in patients with level IV disease; 5) A correlation between lymph node metastases and the development of disseminated disease.     

Prognosis in malignant melanoma

A uniform and practical classification and staging system for melanoma must exist and be widely adopted if useful comparisons between different treatment centers and databases are to be made. This article reviews the 1992 American Joint Committee on Cancer pTNM staging system. In this classification, localized disease without regional nodal involvement is defined as stage I or II, depending on the tumor thickness of the primary melanoma. Regional lymph node involvement and/or in-transit metastasis is defined as stage III, and systemic metastatic disease is defined as stage IV.     

Scintigraphic evaluation of malignant melanoma lesions with Tc-99m tetrofosmin

Two cases of malignant melanoma (primary and metastatic lesions) imaged with Tc-99m tetrofosmin are reported. One patient showed intense uptake in a primary skin lesion of the thorax, and the other patient had accumulation in skin, cerebellum, breast, and lymph node metastases. Like Tc-99m MIBI, Tc-99m tetrofosmin imaging may be of clinical relevance in the evaluation of suspicious skin lesions and in patients with known cutaneous malignant melanoma in the assessment of recurrent disease during follow-up evaluation.     

Expression of CD44 variant isoforms in malignant melanoma

In a variety of human tumors, expression of splice variants of the adhesion molecule CD44 (CD44v) has been described as correlating with tumor progression. Here, we report on the expression of CD44v in melanocytes, nevi, primary melanomas, and cutaneous and lymph node metastases. Thirteen nevi, 65 primary melanomas of varying thickness, 39 cutaneous and 15 lymph node metastases, and melanocytes and a panel of melanoma lines were tested for surface expression of the standard form of CD44 and the variant exons v5, v6, v7, v7-v8, and v10 by immunohistology or fluorescence-activated cell sorting. Melanocytes did not express any variant isoform of CD44. However, nevi, as well as primary melanoma and melanoma metastases, stained to a varying degree with anti-CD44v5, anti-CD44v7-v8, and anti-CD44v10. Exons v6 and v7 were not detected on any of these tissue specimens. Compared with nevi, expression of exon v10 was up-regulated in thick primary tumors and skin metastases. Lymph node metastases displayed elevated levels of exon v5. Expression of CD44v in melanoma lines (n = 20) differed, inasmuch as many lines did not express variant isoforms; in particular, exon v10. Interestingly, however, the few CD44v5-positive melanoma lines metastasized in the nu/nu mouse. Because benign as well as malignant growth of melanocytes was accompanied by expression of CD44 variant isoforms, a linkage between expression of CD44 variant isoforms and malignant transformation or tumor progression was excluded. Considering the function of distinct isoforms, one might speculate that expression of exon CD44v5, which was up-regulated in lymph node metastases compared with nevi and primary melanoma, provided a growth stimulus. Exon v10 is present at high density in epidermal cells. The de novo expression of this exon in nevi and the increased expression in thick melanoma and skin metastases would be in line with the assumption of an anchoring advantage in the surrounding epidermal tissue.     

A new mouse model of experimental melanoma for vaccine and lymphokine therapy

The annual incidence of malignant melanoma is estimated at 10-12 per 100,000 inhabitants in countries of central Europe and the United States, and alarmingly there has been a dramatic upward trend in that estimate. The B16 murine melanoma is a rapidly growing metastatic tumor of spontaneous origin, as are human malignant melanomas. Melanoma cells produce specific antigens which are uniquely different from normal cellular antigens, and the expression of such antigens is the cornerstone for preparation of anti-melanoma vaccines. One major problem in evaluating the effectiveness of vaccination and other biologic therapies is the variability of experimental tumor models. A new metastatic model of experimental melanoma which was developed in our laboratory imitates the major clinical stages of malignant metastatic melanoma: stage I, primary (local) tumor growth and bone marrow invasion; stage II, regional lymph node involvement; and stage III, metastasis to distant organs, such as the lungs. This model has been used successfully for screening vaccines constructed in our laboratory. Immunization with formalinized vaccines (of extracellular antigens, intact melanoma cells, or B700 antigen) or irradiated vaccines (of intact melanoma cells) partially inhibit primary melanoma tumor growth, reduce metastasis to regional lymph nodes and lungs, and significantly increase mean survival time. These anti-tumor effects were improved when polyvalent and monovalent vaccines were combined with IL-2 therapy. We also compared the immunogenic activity of vaccines made from B16 melanoma cells transfected with genes encoding murine IL-2 or GM-CSF, and effects on tumor bearing mice were compared with or without therapy using the corresponding lymphokines. In sum, comparison of antibody production, growth of primary melanoma tumors, number of surviving mice, mean survival time, and percent of mice with lung metastases, showed that the best course of immunotherapy involves vaccination of mice with irradiated B16 melanoma cells transfected to secrete GM-CSF, coupled with GM-CSF therapy.     

Decreased paralysis and better motor coordination with microspinal versus PE10 intrathecal catheters in pain study rats

BACKGROUND: The sentinel lymph node is the first node or nodes to drain a cutaneous melanoma. Sentinel lymph node biopsy is performed to determine whether regional metastases are present. The authors' experience with the new technique of sentinel lymph node biopsy for melanoma of the head and neck is reported. PATIENTS AND METHODS: During the period of January of 1992 to December of 1995, 58 consecutive patients were identified from the melanoma database who had localization of the sentinel lymph node for primary cutaneous melanoma of the head and neck. Techniques for identification of the sentinel node(s) include preoperative lymphoscintigraphy and intraoperative Lymphazurin dye (vital blue dye) and technetium-99m-labeled sulfur colloid injection around the primary tumor site with Neoprobe mapping. RESULTS: Fifty-eight patients (13 female, 45 male), mean age 61 years, with melanoma of the head and neck with a mean Breslow thickness of 2.21 mm. (range, 0.82-6.87 mm.) and no regional lymphadenopathy underwent sentinel node mapping. The sentinel node was successfully identified in 55 patients (95 percent). Blue dye was visualized in 85 of 126 sentinel nodes excised (67 percent), whereas the remainder of the sentinel nodes were localized with the Neoprobe. Forty-nine patients who had successful mapping and sentinel node biopsy had no evidence of metastatic disease in the sentinel node or other nodes in the basin. Six of the fifty-five patients (11 percent) had evidence of micrometastatic disease, and all six had the sentinel node as the only site of metastasis. Five of six patients with micrometastases had a subsequent neck dissection and/or superficial parotidectomy. None of these patients had evidence of "skip metastases" with a negative sentinel node and higher level nodes positive for metastases. In total, 6 of the 18 sentinel nodes (33 percent) identified in these six patients contained micrometastatic disease, whereas none of the 139 other nodes sampled had any evidence of metastases. The exact probability that all six unpaired observations would consist of involvement of only the sentinel nodes is p = 0.0312. CONCLUSIONS: By combining the two mapping techniques in patients with melanoma of the head and neck, the sentinel node(s) can be mapped and identified individually, similar to melanoma in other locations. The sentinel nodes have been shown to contain the first evidence of regional metastatic melanoma. This staging information can be used to plan therapeutic node dissections and adjuvant therapy that may have a survival benefit in patients with stage III melanoma of the head and neck. Lymphatic mapping can be used to make the surgical care of the melanoma patient more conservative, so that only those patients with solid evidence of regional node metastases are subjected to the morbidity and expense of a complete node dissection and the toxicities of adjuvant therapy.     

The National Cancer Data Base report on cutaneous and noncutaneous melanoma: a summary of 84,836 cases from the past decade. The American College of Surgeons Commission on Cancer and the American Cancer Society

BACKGROUND: This study reviews the case-mix characteristics, management, and outcomes of melanoma cases occuring in the U.S. within the last decade. METHODS: Analyses of the National Cancer Data Base (NCDB) were performed on cases diagnosed between 1985 through 1994. A total of 84,836 cases comprised of cutaneous and noncutaneous melanomas were evaluated. RESULTS: The percentages of melanomas that were cutaneous, ocular, mucosal, and unknown primaries were 91.2%, 5.2%, 1.3%, and 2.2%, respectively. For cutaneous melanomas, the proportion of patients presenting with American Joint Committee on Cancer Stages 0, I, II, III, and IV were 14.9%, 47.7%, 23.1%, 8.9%, and 5.3%, respectively. Factors associated with decreased survival included more advanced stage at diagnosis, nodular or acral lentiginous histology, increased age, male gender, nonwhite race, and lower income. Multivariate analysis identified stage, histology, gender, age, and income as independent prognostic factors. For ocular melanomas, 85.0% were uveal, 4.8% were conjunctival, and 10.2% occurred at other sites. During the study period, there was a large increase in the proportion of ocular melanoma patients treated with radiation therapy alone. For mucosal melanomas, the distribution of head and neck, female genital tract, anal/rectal, and urinary tract sites was 55.4%, 18.0%, 23.8%, and 2.8%, respectively. Patients with lymph node involvement had a poor prognosis. For unknown primary melanomas, the distribution of metastases as localized to a region or multiple sites at presentation was 43.0% and 57.0%, respectively. Surgical treatment of patients with unknown primary site of the melanoma resulted in better survival compared with no treatment. CONCLUSIONS: Treatment of early stage cutaneous melanoma resulted in excellent patient outcomes. In addition to conventional prognostic factors, socioeconomic factors were found to be associated with survival.     

Pathology of the lymph nodes in patients with malignant melanoma

The poor survival rate for patients with regional lymph node metastases of malignant melanoma reflects the strong association between lymph node and subsequent visceral metastases. The authors discuss clinical considerations, pathologic risk factors, selective lymphadenectomy, examination of lymph node dissections, difficulties of diagnosis, and prognosis.     

Tumor-associated antigen TA-90 immune complex assay predicts subclinical metastasis and survival for patients with early stage melanoma

BACKGROUND: TA-90 is a tumor-associated antigen first identified in the urine and sera of patients with metastatic melanoma. In the early stages of disease, TA-90 is present in circulating immune complexes (ICs) that may be detected with an antigen specific enzyme-linked immunosorbent assay (ELISA). In this study, the authors evaluated the efficacy of the TA-90 IC assay in detecting subclinical metastasis of early stage melanoma and predicting the survival of patients with this disease. METHODS: Archival sera were collected preoperatively from 114 patients who underwent wide excision with or without regional lymphadenectomy in the treatment of clinical Stage I melanoma. Sera were analyzed for TA-90 IC in a blinded fashion, and results were correlated with the patient's clinical course as determined by database and chart review. Subclinical metastases were considered present at the time of surgery if the lymphadenectomy specimen was pathologically positive and/or the patient subsequently developed recurrence. RESULTS: The TA-90 IC assay predicted subclinical metastasis in 43 of 56 patients (P < 0.0001), with 14 false-positive and 13 false-negative results. Sensitivity and specificity for the detection of occult metastasis were 77% and 76%, respectively. Positive and negative predictive values were 75% and 77%, respectively. Fifteen of 18 tumor positive regional lymph node basins (83%) and 34 of 46 recurrences (74%) were accurately predicted when considered independently (P < 0.004). Preoperative TA-90 IC status was also highly correlated with survival: 5-year overall and disease free survival rates were 63% and 46%, respectively, for the TA-90 IC positive group, compared with 88% and 82%, respectively, for the TA-90 IC negative group (P=0.0001). A multivariate analysis with standard prognostic variables identified preoperative TA-90 IC status as a strong, independent prognostic factor for both overall and disease free survival. CONCLUSIONS: To the authors' knowledge, TA-90 is the first tumor marker that accurately predicts subclinical metastatic disease and survival for patients with early stage melanoma. For this reason, the TA-90 IC assay has the potential to improve dramatically the prognostic evaluation of patients with this disease. Its role in postoperative risk stratification and early detection of recurrence is being evaluated in a prospective study.     

Desmoplastic and desmoplastic neurotropic melanoma: experience with 280 patients

BACKGROUND: It has been suggested that desmoplastic melanoma (DM) and desmoplastic neurotropic melanoma (DNM) are associated with worse prognoses and higher local recurrence rates than other forms of melanoma. In the current study, a large series of patients with DM and DNM treated at a tertiary referral center was reviewed. METHODS: For 190 patients with DM and 90 patients with DNM accrued over a 10-year period, clinical features were recorded and all available histopathology was reviewed. The associations between clinical and pathologic variables, biologic behavior, and eventual outcome were analyzed. RESULTS: The male-to-female ratio was 1.75:1 and the median patient age 61 years. The median tumor thickness was 2.5 mm, and 44% of cases were amelanotic. Five-year survival was 75%. Significant predictors of overall survival were a high mitotic rate (P=0.003) and tumor thickness (P=0.011). All the DNMs exceeded 1.5 mm in thickness and were graded as Clark's level IV or V. There was a significant increase in local recurrence when neurotropism was present (P < 0.001). The rate of local recurrence was not higher for DM than for other cutaneous melanomas. CONCLUSIONS: There was no statistically significant difference in survival for patients with DM and those with DNM, and overall survival for both was similar to that for patients with other cutaneous melanomas. However, there was a lower rate of regional lymph node metastasis at initial presentation and as the first recurrence for both DM and DNM. The local recurrence rate was higher when the surgical clearance margin was <1 cm and when neurotropism was present.     

Human D2 and D4 dopamine receptors couple through betagamma G-protein subunits to inwardly rectifying K+ channels (GIRK1) in a Xenopus oocyte expression system: selective antagonism by L-741,626 and L-745,870 respectively

OBJECTIVE: To develop a prognostic model, based on clinical and pathological data, to estimate the probability of micrometastasis in the sentinel lymph node in patients with malignant melanoma. DESIGN: Retrospective analytical study. SETTING: University medical center. PATIENTS: Two hundred fifteen patients with American Joint Committee on Cancer stages I and II cutaneous malignant melanoma underwent sentinel lymph node biopsy. MEASUREMENTS: Presence of microscopic melanoma in the sentinel lymph node(s). Clinical attributes recorded included age, sex, and location of the primary melanoma. Pathological attributes recorded before lymph node evaluation included ulceration, microsatellites, angiolymphatic invasion, mitotic rate, tumor infiltrating lymphocytes, and regression. RESULTS: Forty-six patients (21.4%) overall had a positive sentinel lymph node. Patients with tumor thickness ranging from 3.0 to 3.9 mm had the highest incidence (50%) of nodal involvement, followed by those with tumors 4.0 to 4.9 mm thick (41%). Patients with melanomas measuring greater than 4.9 mm thick and those between 1.0 and 2.9 mm had a similar rate of nodal involvement (16%-17%). Clinical characteristics had minimal correlation with nodal status in multivariate analysis. The total number of histological high-risk features was significantly correlated with sentinel lymph node involvement. Important pathological risk factors included ulceration, high mitotic rate, angiolymphatic invasion, and microsatellites. Patients with tumor thickness greater than 1.0 mm but lacking these features had a 14% risk of occult metastases. CONCLUSION: Among patients with clinically node-negative primary melanoma, the presence of 1 or more high-risk histological features significantly increases the incidence of microscopic nodal involvement and can be used to predict the likelihood of a positive sentinel lymph node biopsy.     

A multifactorial analysis of melanoma: prognostic histopathological features comparing Clark's and Breslow's staging methods

A multifactorial analysis was used to identify the dominant prognostic variables affecting survival from a computerized data base of 339 melanoma patients treated at this institution during the past 17 years. Five of the 13 parameters examined simultaneously were found to independently influence five year survival rates: 1) pathological stage (I vs II, p = 0.0014), 2) lesion ulceration (present vs absent, p = 0.006), 3) surgical treatment (wide excision vs wide excision plus lymphadenectomy, p = 0.024), 4) melanoma thickness (p = 0.032), and 5) location (upper extremity vs lower extremity vs trunk vs head and neck, p = 0.038). Additional factors considered that had either indirect or no influence on survival rates were clinical stage of disease, age, sex, level of invasion, pigmentation, lymphocyte infiltration, growth pattern, and regression. Most of these latter variables derived their prognostic value from correlation with melanoma thickness, except sex which correlated with location (extremity lesions were more frequent on females, trunk lesions on males). This statistical analysis enabled us to derive a mathematical equation for predicting an individual patient's probability of five year survival. Three categories of risk were delineated by measuring tumor thickness (Breslow microstaging) in Stage I patients: 1) thin melanomas (<0.76 mm) were associated with localized disease and a 100% cure rate: 2) intermediate thickness melanomas (0.76-4.00 mm) had an increasing risk (up to 80%) of harboring regional and/or distant metastases and 3) thick melanomas (>/=4.00 mm) had a 80% risk of occult distant metastases at the time of initial presentation. The level of invasion (Clark's microstaging) correlated with survival, but was less predictive than measuring tumor thickness. Within each of Clark's Level II, III and IV groups, there were gradations of thickness with statistically different survival rates. Both microstaging methods (Breslow and Clark) were less predictive factors in patients with lymph node or distant metastases. Clinical trials evaluating alternative surgical treatments or adjunctive therapy modalities for melanoma patients should incorporate these parameters into their assessment, especially in Stage I (localized) disease where tumor thickness and the anatomical site of the primary melanoma are dominant prognostic factors.     

Skip metastasis to the mediastinal lymph nodes in non-small cell lung cancer

BACKGROUND: Whether any difference exists in clinical characteristics between resected non-small cell lung cancer with either skip or ordinary mediastinal lymph node metastases (N2 disease) needs to be clarified. METHODS: There were 110 patients with stage IIIA N2 disease. Thirty-three patients demonstrating no metastasis at the hilar nodes [skip (+) group] were compared with the other 77 patients [skip (-) group]. To investigate the extent of nodal involvement, we classified the mediastinal lymph nodes into three regions (superior, inferior, or aortic). RESULTS: There were no significant differences regarding histologic type, T status, or the site of the primary tumors between the skip (+) and the skip (-) N2 groups. In the skip (+) group, mediastinal node metastasis was found in only one region (level 1) in 30 patients (90.9%) and in two regions (level 2) in 3 (9.1%), whereas 28 patients (36.4%) from the skip (-) group revealed mediastinal metastasis at two or three regions (level 2 or 3). The overall survival rate at 5 years after operation was 35% in the skip (+) group and 12.7% in the skip (-) group (p = 0.054). This favorable clinical outcome in the skip (+) group could be explained partially by the higher proportion of patients with level 1 metastases. Furthermore, regarding patients with level 1 disease, the skip (+) group tended to have a better prognosis than the skip (-) group (p = 0.096). CONCLUSIONS: These results suggest that patients with skip mediastinal lymph node metastases represent a unique subgroup of N2 disease.     

Adenocarcinoma of the pancreas: detection of occult metastases in regional lymph nodes by a polymerase chain reaction-based assay

BACKGROUND: Stage I (T1-2NOM0) adenocarcinoma of the pancreas is associated with a 5-year survival rate of 15-25%. Despite apparently curative resection and pathologic staging indicating localized disease, these cancers recur. The authors hypothesized that there exists microscopic regional disease that is not detected by surgical exploration or routine histopathology. METHODS: Because 90-95% of pancreatic cancers exhibit codon 12 K-ras mutations, the authors examined regional lymph nodes for mutated K-ras as a marker of metastasis. DNA was extracted from paraffin embedded archival specimens (primary tumors and histologically negative lymph nodes) of patients with Stage I pancreatic adenocarcinoma. The target region of K-ras was amplified by polymerase chain reaction (PCR) and tested for codon 12 mutation by BstN1 restriction digestion (restriction fragment length polymorphism [RFLP]) that recognized normal but not mutated sequences. Cell lines that harbored normal or mutated K-ras and resected jejunum or gallbladder were used as controls. The regional lymph nodes of 22 patients whose tumors harbored mutated K-ras were tested. RESULTS: Dilution experiments with normal and mutant control cell line DNA demonstrated an assay sensitivity for mutated K-ras of 0.1%. Mutated K-ras was found in at least 1 regional lymph node in 16 (73%) of 22 patients with pathologic Stage I pancreatic adenocarcinoma, which suggested metastases not detected by routine histopathology. DNA sequence analysis was performed in four patients and confirmed identical point mutations in the primary tumor and accompanying PCR/RFLP positive lymph nodes. CONCLUSIONS: Pathologic examination of regional lymph nodes in pancreatic adenocarcinoma specimens fails to detect metastases in many patients. Lymph node micrometastasis is one reason for the poor survival rates observed among patients with Stage I cancers. PCR/RFLP may have a role in staging early pancreatic cancers.