Cancer incidence, mortality and survival: trends in four leading sites

Cancer mortality rates in the United States have stabilized in the past few years after rising for more than 50 years. Incidence and mortality rates for all cancers tend to be higher among men than women, among blacks than whites and among those over age 65. In 1994 cancer of the lung, prostate, breast, and colon/rectum (colorectal) will account for an estimated 57 percent of all new cancer cases and 55 percent of cancer deaths. Analysis of incidence, mortality and survival rates of these four major cancers indicate some encouraging trends. That is, even though age-adjusted incidence rates continue to increase, it appears that educational and screening efforts are having a positive influence on mortality rates. Lung cancer incidence has declined in recent years following a decrease in smoking among men that began some 20 years ago; evidence also indicates a start of a declining trend in their mortality from this disease, as well. Lung cancer incidence and mortality rates among women, however, continue to rise. In 1986 lung cancer became the leading cause of cancer deaths among women. Increased use and improved techniques of cancer detection for prostate, breast and colorectal cancers are resulting in larger numbers of these cancers being detected at early stages when they are more readily treatable. It is hoped that such activities will ultimately reduce mortality for these three major cancer sites.     

Longitudinal study of socio-economic differences in the incidence of stomach, colorectal and pancreatic cancers

Using the ONS Longitudinal Study, the incidence of stomach, colorectal and pancreatic cancers from 1976-90 was examined for men and women aged 30 years and over by their housing tenure and occupational social class. Large socio-economic differences in the incidence of stomach cancer for both men and women were found. The pattern of colorectal cancer was less clear, with women in more advantaged social groups experiencing higher incidence while for men there was no significant association. Pancreatic cancer showed no association with socio-economic status. Consistent findings with each indicator strengthen the interpretation of the results. Risk factors for these cancers are known to vary by socio-economic status, and this study demonstrates the importance of continued monitoring of the distribution of cancer incidence.     

Relapsing pancreatitis due to juxta-pancreatic duodenal duplication cyst with pancreatic ductal communication

BACKGROUND: Various animal studies and ecologic studies suggest an inverse association between low dietary selenium intake and risk of various types of cancer. PURPOSE: The goal of this prospective cohort study was to investigate the association between toenail selenium levels and risks of stomach cancer and colorectal cancer. METHODS: Our cohort study on diet and cancer started in The Netherlands in 1986 with enrollment of 120,852 subjects aged 55-69 years. Of this number, 58,279 were men and 62,573 were women. Following the case-cohort approach for analysis of the data, we randomly selected from the cohort a subcohort of 3500 subjects (1688 men and 1812 women). After 3.3 years of follow-up, 155 incident cases of microscopically confirmed stomach cancer, 313 cases of colon cancer, and 166 cases of rectal cancer had been detected in the cohort. Toenail selenium data were available for 104 patients with stomach cancer, 234 with colon cancer, and 113 with rectal cancer and for 2459 subjects from the subcohort. RESULTS: In a multivariate analysis, the relative rates (RRs) of stomach cancer for subjects in increasing quintiles of toenail selenium level were 1.00, 0.44, 0.59, 0.84, and 0.64 (trend, P = .491). For men, there was some evidence for an inverse association between toenail selenium levels and stomach cancer: The RR for those in the highest compared with the lowest quintile of toenail selenium was 0.40 (95% confidence interval = 0.17-0.96), but the trend was not statistically significant (P = .136). For stomach cancer in women, there was no negative association with toenail selenium levels. Toenail selenium level was not associated with the risk of colon or rectal cancer. After exclusion of cases diagnosed in the 1st year of follow-up, the RRs of colon cancer for increasing quintiles of toenail selenium were 1.00, 1.27, 1.17, 0.75, and 1.07 (trend, P = .544); for rectal cancer, RR estimates were 1.00, 1.73, 0.83, 1.58, and 1.12 (trend, P = .890). CONCLUSIONS: These data support a suggestive but inconsistent inverse association between selenium levels and risk of stomach cancer. Our findings, like those of other studies, do not suggest an inverse association with risk of colorectal cancer.     

Cancer incidence and mortality in France in 1975-95

The aims of the European Network of Cancer Registries (ENCR) are to improve the quality, comparability and availability of cancer registry data in Europe. This paper on cancer incidence and mortality in France presents the most recent available data, with short-term projections to 1995, and a commentary based, where possible, on epidemiological research carried out in France. Cancer incidence in men in France increased throughout the study period 1975 to 1995, from 92,000 new cases in 1975 to about 135,000 in 1995. This increase was partly due to the ageing of the French population, but incidence rates have also increased, particularly from 1975 to 1985. The trend appears to be levelling off in the 1990s, with an incidence rate in 1995 of about 482 per 100,000 (this and subsequent rates quoted are standardized to the European Standard Population). Among women, the all-cancer incidence rates also increased during the 1970s and 1980s. Although the rate of increase was less pronounced than in men, the trend is continuing in the 1990s. The estimated age standardized rate in 1995 was 309 per 100,000, representing 104,000 new cases. The main components of these changes in the last decade were, for men, increases in large bowel and prostate cancer, which have been partly compensated for by decreases in oral cavity, larynx and stomach cancer. For women the trend was dominated by the continuing increase in breast cancer with increases also in large bowel and lung cancers. Of the numerically important cancers in women, only stomach cancer has shown a clear decline. The situation in 1995 was that breast cancer remained the predominant cancer affecting women in France, accounting for almost one third of all new cases of cancer diagnosed and one fifth of cancer deaths. The next most frequent cancers in women were those of the large bowel. Regrettably, incidence rates of both breast and bowel cancer are increasing in women. For men in France the most frequent cancers in 1995 were those of the prostate, large bowel and lung, all of which increased in incidence since 1975. Although it is estimated that there will be more newly diagnosed cases of prostate cancer than lung cancer in 1995, the latter will cause many more deaths, particularly of young men.     

Average intake of anti-oxidant (pro)vitamins and subsequent cancer mortality in the 16 cohorts of the Seven Countries Study

This ecologic study aimed to investigate whether differences in population mortality from lung, stomach and colorectal cancer among the 16 cohorts of the Seven Countries Study could be explained by differences in the average intake of anti-oxidant (pro)vitamins. In the 1960s, detailed dietary information was collected in small sub-samples of the cohorts by the dietary record method. In 1987, food-equivalent composites representing the average food intake of each cohort at baseline were collected locally and analyzed in a central laboratory. The vital status of all participants was verified after 25 years of follow-up. The average intake of vitamin C was strongly inversely related to the 25-year stomach-cancer mortality (r = -0.66, p = 0.01), also after adjustment for smoking and intake of salt or nitrate. The average intake of alpha-carotene, beta-carotene, and alpha-tocopherol were not independently related to mortality from lung, stomach or colorectal cancer, nor was vitamin C related to lung and colorectal cancer.     

Microsatellite instability in early onset and familial colorectal cancer

Hereditary non-polyposis colorectal cancer syndrome (HNPCC) is often considered to be the most common form of inherited colorectal cancer, although its precise incidence is unknown. The clinical diagnosis of HNPCC relies on a combination of family history and young age of onset of colorectal cancer, but as many familial aggregations of colorectal cancer do not fulfil the strict diagnostic criteria, HNPCC might be underdiagnosed. The majority of HNPCC families have germline mutations in mismatch repair (MMR) genes, such as MSH2 or MLH1, so that HNPCC cancers characteristically exhibit DNA replication errors (RERs) at microsatellite loci. Although an RER positive phenotype in tumours can also result from somatic mutations in an MMR gene, the prevalence of RER + tumours should provide a maximum estimate of the incidence of germline MMR gene mutations in patients with early onset and familial colorectal cancer. We investigated colorectal cancers for RERs from (1) a population based study of 33 patients with colorectal cancer aged 45 years or less, (2) 65 kindreds with familial colorectal cancer which only partially fulfilled the criteria for the diagnosis of HNPCC, and (3) 18 cancers from 12 HNPCC kindreds. Seven of 33 patients (21%) with colorectal cancer aged 45 years or less had an RER + cancer, with only two of these having a clear family history of HNPCC. A greater proportion of RER + tumours (5/7) occurred proximal to the splenic flexure than RER - tumours (4/26; chi2 = 6.14, p < 0.025). RERs were detected in all 18 cancers from HNPCC patients but in only six of 65 non-HNPCC familial colorectal cancer kindreds (9%; chi2 = 52.2, p < 0.0005). These findings suggest that most cancers in patients diagnosed at 45 years of age or less and familial aggregations of colorectal cancer which do not fulfil HNPCC diagnostic criteria do not have germline mutations in MSH2 and MLH1. Hence population screening for germline mutations in these genes is unlikely to be an efficient strategy for identifying people at high risk of developing colorectal cancer.     

Clinical implications of clubfoot histopathology

PURPOSE: Multiple primary cancers are a feature of hereditary nonpolyposis colorectal cancer in which defects in DNA repair mechanisms result in accumulation of replication errors within tumor DNA. We assessed replication error incidence in multiple primary cancer patients who may have similar genetic defects. METHODS: DNA was obtained from 69 patients from the Yorkshire region who had developed colorectal cancer and one other primary tumor from the hereditary nonpolyposis colorectal cancer tumor spectrum (28 colorectal, 12 stomach, 15 ovary, and 14 uterus). DNA was also obtained from 86 sporadic, single primary cancer patients attending a colorectal cancer clinic. Replication error status was assessed at five microsatellite loci using fluorescent polymerase chain reaction and computer-assisted analysis. RESULTS: The replication error phenotype was observed in 7 of 86 (8 percent) of the sporadic single primary patients. This compared with 23 of 69 (33 percent) of the multiple primary group (P < 0.001). Replication error was also observed more frequently in each subgroup. Even excluding patients from families meeting the Amsterdam criteria (likely to be hereditary nonpolyposis colorectal cancer and have the replication error phenotype), this increased frequency remained in both the multiple primary group (P < 0.005) and multiple colorectal and colorectal/uterine subgroups (P < 0.001). CONCLUSIONS: Results suggest that genetic instability plays an important role in development of multiple primary cancers, particularly from certain cancer subsets. Testing for replication errors may be an appropriate way of identifying individuals at risk of multiple primary cancers.     

Estimation and projections of colorectal cancer trends in Italy

BACKGROUND: Occurrence of and prognosis for tumours of the colon and rectum are thought to be changing rapidly due to simultaneous changes in risk factor prevalence, early diagnosis and treatment. In this paper time trends of morbidity, survival and mortality for colorectal cancer during the period 1970-1990 are estimated and analysed. METHODS: Mortality trends were obtained from official death certificates. Relative survival rates were computed from population-based cancer registries. Incidence and prevalence rates were estimated from mortality and survival data. RESULTS: Incidence rates were increasing during the period considered, with a lower rate of increase for the youngest birth cohorts. Relative survival rates of both colon and rectum cancers were higher for women, and for younger age groups, and were positively associated with period of diagnosis. No significant survival difference among the cancer registries used was found. A total of about 155,000 prevalent cases, 40% of which had been diagnosed > or = 7 years before, were estimated in the Italian population for the year 1990. Mortality rates were slightly increasing for men and stable for women. Projections of colorectal cancer trends to the year 2000 indicate major expected rises in both incidence and prevalence. CONCLUSION: Colorectal cancer represents a problem of growing impact for health services in Italy. This conclusion can probably be extended to many developed countries.     

Genetic implications of double primary cancers of the colorectum and endometrium

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant condition predisposing to cancers of the colorectum and endometrium. Endometrial cancer is the most commonly occurring extracolonic cancer in HNPCC. Estimates of the cumulative incidence of endometrial cancer in women with mutations in the HNPCC genes range from 22-43%. In order to determine how frequently double primary cancers of the colorectum and endometrium are the result of a hereditary factor, we conducted a registry based study in Ontario and Quebec, Canada. We obtained pedigrees on 80 women diagnosed with double primary cancers of the colorectum and endometrium at less than 70 years of age. Family histories of cancer were obtained for all first degree relatives of these women and cancer rates were compared with age standardised provincial incidence rates in order to estimate the relative risks. There was a total of 82 cancers observed in relatives below the age of 55, compared with 31.2 expected, giving a relative risk of 2.6 (95% confidence interval (CI) 2.1-3.3). The relative risk for colorectal cancer below 55 was 16.1 (95% CI 11.6-21.8). This risk decreased with increasing age of onset of cancers in probands. For probands with both colorectal and endometrial cancer diagnosed under the age of 55, the relative risk of colorectal cancer in relatives below the age of 55 was 30.5 (95% CI 18.8-46.6). Similar patterns were observed for endometrial and pancreatic cancer. There were non-significant increases in rates of cancer of the oesophagus, stomach, small intestine, and bladder. There was no increased risk of breast cancer. The risk of lung cancer was decreased, especially in older relatives. Our findings indicate the presence of a significant genetic component of cancer in women with double primary cancers of the colorectum and endometrium.     

Cancer risk and social inequalities in Italy

STUDY OBJECTIVE: To investigate social differences in cancer incidence in Turin, Italy in 1985-87. DESIGN: A cancer incidence follow up study of the turin population in relation to socioeconomic characteristics was performed through record linkage between the 1981 census and the cancer registry. A case-control study nested in the cohort was analysed, where cases were subjects with a new diagnosis of cancer in 1985-87 and controls were a sample of the Turin population, frequency matched by sex and age group. Incidence odd ratios (ORs) were calculated for social classes (defined by education, housing tenure, and socioeconomic group) using a logistic regression model. SETTING: The study population comprised subjects included in the 1981 Turin census (n approximately equal to 1,100,000) who were still alive, 20-69 years old, and were resident in Turin in the middle of study period. PARTICIPANTS: The analyses were based on 4215 male and 3451 female cases, and on 16,913 male and 13,838 female controls. MAIN RESULTS: Compared with the highest educational level, the men in the lowest one showed an OR > 2 for respiratory cancers; OR = 1.48 for stomach cancer; and ORs < 0.7 for skin, colorectal, and prostate cancers. Women with a primary school education were protected against colorectal (OR = 0.71), skin (OR = 0.59), and breast cancer (OR = 0.66) compared with university degree women, but were at risk for cancer of the cervix (OR = 2.33) and stomach cancer (OR = 2.84). The association between educational level (primary school v university) and lung cancer risk is negative for men (OR = 2.47) and positive for women (OR = 0.62), while the association with housing tenure is negative for both sexes (OR = 1.44). CONCLUSIONS: The socioeconomic distribution of some risk factors (for example smoking, alcohol, and diet) in Italy can partially explain the differences in respiratory and digestive cancers. "Unbalanced" health promotion interventions, targeted at social groups with the highest prevalences of risk factors, and national policies for increasing the level of education in the country may play an important role in reducing social differences in cancer risk.     

Obesity and cancer risk: a Danish record-linkage study

A cohort of 43,965 obese persons was accrued on the basis of discharge registrations from Danish hospitals, and incidence of cancer in the cohort was compared to that in the Danish population as a whole using indirect standardisation for age and period. Increased incidence was observed for cancer of the uterine corpus independently of age [114 cases, relative risk (RR) = 2.0, confidence interval 1.6-2.4], and for breast cancer in women above the age of 70 (133 cases, RR = 1.2). These findings are consistent with previous studies. In younger women, breast cancer occurred less frequently and ovarian cancer occurred more frequently than expected. Increased incidence was observed for cancers of the oesophagus (26 cases, RR = 1.9) and the liver (58 cases, RR = 1.9), probably reflecting an increased prevalence of excessive alcohol consumption in the cohort. Increased incidence was furthermore observed for cancers of the pancreas (101 cases, RR = 1.7), the prostate (96 cases, RR = 1.3) and the colon (195 cases, RR = 1.2), which may indicate the existence of risk factors which are common to obesity and to these cancers, for example, dietary habits. Kidney cancer was increased in women only. Overall, the incidence of cancer was increased by 16% in the cohort. The results were essentially unchanged by restriction to the subcohort of 8207 persons in whom obesity was the primary discharge diagnosis, and were also similar in the first year of follow-up after hospital discharge. Selection bias is, therefore, not likely to have influenced the results.     

Stress and HIV disease progression: psychoneuroimmunological framework

BACKGROUND AND METHODS: A retrospective cohort study was conducted to estimate the effects of low-level exposure to external (penetrating) radiation on cancer mortality among 4,563 workers monitored for external radiation between 1950 and 1993 at a nuclear research and production facility in Southern California. RESULTS: Of the 875 deaths that occurred before 1995, 258 were due to cancer as the underlying cause. External comparisons of male subjects with the U.S. white male population indicated that the workers had lower rates of dying from all causes and all cancers, but a higher rate of dying from leukemia. Internal comparisons of workers exposed at different dose levels, using risk-set analyses with adjustment for confounders, demonstrated an increased mortality rate in workers exposed to 200 mSv for hemato- and lymphopoietic cancers and for lung cancer. Mortality rates for total cancers and "radiosensitive" solid cancers increased monotonically with cumulative radiation dose, but no trends were observed for "nonradiosensitive" cancers. CONCLUSIONS: Despite possible residual confounding and low precision for estimating effects on specific cancers, these findings indicate that chronic, low-level radiation exposure may have more generalized carcinogenic effects than have been observed in most previous investigations. Such effects may have become evident as a result of the relatively long follow-up period in the present study.     

Detection of pathogenic Yersinia enterocolitica in environmental waters by PCR

We analyzed cancer incidence and mortality in a cohort of 22,597 Swedish women who were prescribed replacement hormones. After 13 years of follow-up in national registries, 2,330 incident cancer cases and 848 cancer deaths were observed. Overall, our results were reassuring since incidence rate ratios (SIRs) for 16 cancer sites and mortality ratios (SMRs) for all 10 examined sites were at, or lower than, unity. However, we found that exposure to an estrogen-progestin combined brand was associated with an increasing relative risk of breast cancer with follow-up time, the SIR reaching 1.4 (95% CI 1.1-1.8) after 10 years of follow-up. The relative risk of endometrial cancer was substantially increased, with the highest SIR of 5.0 (95% CI 1.6-5.9) in women prescribed estrogens alone, whereas those given an estrogen-progestin combination showed no elevation in risk. The risk estimates for liver and biliary tract cancers and for colon cancer were reduced by about 40%, notably in women prescribed the estradiol-progestin compound. Further detailed analyses revealed no evidence of adverse or protective effects on the risk of ovarian, uterine cervical, vulvar/vaginal, rectal, pancreatic, renal, lung, thyroid and other endocrine cancers, brain tumors, malignant melanoma or other skin cancers. Hormone replacement therapy was not associated with an increase in mortality for any cancer site, at this time of follow-up. For breast and endometrial cancers, SMRs were below baseline but tended to increase with follow-up time. We conclude that hormone replacement increases the endometrial-cancer risk after unopposed estrogens and the breast-cancer risk-notably after estrogen-progestin combined therapy-and tentatively suggest that it exerts a protective effect against colon and liver cancer risks.     

A systematic review of the effects of screening for colorectal cancer using the faecal occult blood test, hemoccult

OBJECTIVE: To review effectiveness of screening for colorectal cancer with faecal occult blood test, Hemoccult, and to consider benefits and harms of screening. DESIGN: Systematic review of trials of Hemoccult screening, with meta-analysis of results from the randomised controlled trials. SUBJECTS: Four randomised controlled trials and two non-randomised trials of about 330 000 and 113 000 people respectively aged >=40 years in five countries. MAIN OUTCOME MEASURES: Meta-analysis of effects of screening on mortality from colorectal cancer. RESULTS: Quality of trial design was generally high, and screening resulted in a favourable shift in the stage distribution of colorectal cancers in the screening groups. Meta-analysis of mortality results from the four randomised controlled trials showed that those allocated to screening had a reduction in mortality from colorectal cancer of 16% (relative risk 0.84 (95% confidence interval 0.77 to 0.93)). When adjusted for attendance for screening, this reduction was 23% (relative risk 0.77 (0.57 to 0.89)) for people actually screened. If a biennial Hemoccult screening programme were offered to 10 000 people and about two thirds attended for at least one Hemoccult test, 8.5 (3.6 to 13.5) deaths from colorectal cancer would be prevented over a period of 10 years. CONCLUSION: Although benefits of screening are likely to outweigh harms for populations at high risk of colorectal cancer, more information is needed about the harmful effects of screening, the community's responses to screening, and costs of screening for different healthcare systems before widespread screening can be recommended.     

Brain potentials associated with eye fixations during visual tasks under different lighting systems

The incidence of non-familial multiple primary cancer in colorectal cancer patients has increased in recent years in Japan. To clarify the characteristic genetic aberrations in such multiple cancers, we examined structural chromosomal aberrations by fluorescence in situ hybridization, using chromosome 17-specific and p53 cosmid DNA probes. We established short-term cultures of 78 surgical specimens and were able to obtain observable metaphase spreads in 23 single colorectal cancer specimens and in 6 colorectal cancer specimens from patients with double primary cancers. The frequency of chromosome 17 and/or p53 locus translocation was significantly greater in tumors with double cancer than in single colorectal cancers (P < 0.05 and P < 0.01, respectively). These aberrations in double cancers frequently appeared even at an early Dukes' stage (A and B) of colorectal carcinoma. Our results suggest that translocation of chromosome 17 and the p53 locus may be specific genetic events probably associated with carcinogenesis of multiple primary cancers in colorectal cancer.     

Incidence of free colorectal cancer cells on the peritoneal surface

BACKGROUND: The etiology and significance of port site recurrence occurring after laparoscopic-assisted resection for colorectal cancers will not be determined until controlled clinical trials determine if it is a predictor of outcome. Indirect evidence in support of transcoelomic spread of viable cancer cells to port sites during resection can be postulated by the presence of free cells on the fresh surface of colorectal specimens during primary resection. PURPOSE: The study contained herein was undertaken to determine the incidence of free surface colorectal cancer cells by cytology during elective open resection and to correlate their presence with clinicopathologic variables. METHODS: Fresh clamped and ligated consecutive colorectal cancer specimens were assessed in the operating room during primary resection for the presence of free colorectal cancer cells during an 18 month period at one institution. Clinicopathologic variables were assessed prospectively and blinded to cytology results. Interobserver reliability of cytologists was excellent (unweighted kappa, 0.93). RESULTS: Overall, 15 of 103 (14.6 percent) colorectal cancers had positive cytology for cancer cells on the peritoneal or perirectal surface of the bowel. T3 and T4 tumors, the size or site of the tumor, lymph node status, mucinous characteristic, degree of differentiation, and the presence of vascular or neural invasion did not reach statistical significance as predictors of positive cytology in this study sample. The operative procedure performed was a statistically significant predictor of positive cytology. More than 50 percent of lymph nodes involved (28 percent), poorly differentiated tumors (28 percent), and the presence of liver metastases (22 percent) demonstrated a higher incidence of positive cytology, but this did not reach significant levels because of the limited power of the study sample for subgroup analysis. DISCUSSION: The presence of free surface colorectal cancer cells gives only indirect support to the transcoelomic route to port site recurrence. The significance and true incidence will only be determined by prospective database analysis and randomized, controlled trials.     

Specificity of the Speed''s test: arthroscopic technique for evaluating the biceps tendon at the level of the bicipital groove

A historical cohort study was conducted in Misasa town, Tottori prefecture, Japan, where radon spas have been operating for a long time. Misasa town was divided into an elevated radon level area and a control area, with mean indoor radon levels of about 60 and 20 Bq/m3, respectively. In total, 3,083 subjects in the elevated radon level area and 1,248 in the control area, all aged 40 or older on January 1, 1976, were followed up until December 31, 1993, for a mean period of 14 years. The mortality rates from all causes exhibited no difference between the elevated radon level area and the control area for both sexes. No difference was observed in the incidence of all-site cancers (age, period-adjusted rate ratios by Poisson regression, RR = 1.06, 95% confidence interval (CI) 0.79-1.42 for males, RR = 0.90, 95% CI 0.65-1.24 for females), while stomach cancer incidence seemed to decrease for both sexes (RR = 0.70, 95% CI 0.44-1.11 for male, RR = 0.58, 95% CI 0.34-1.00 for female) and lung cancer incidence for males only seemed to increase (RR = 1.65, 95% CI 0.83-3.30 for male, RR = 1.07, 95% CI 0.28-4.14 for female) in the elevated radon level area. Caution is needed in the interpretation of these findings, however, since the individual exposure level was not measured and major confounding factors, such as smoking and diet, could not be controlled in this study.     

Treatment of aggression and irritability after head injury

Epidemiological characteristics of colorectal cancer may differ by particular anatomical subsite, suggesting that the subsite-specific colorectal cancers may represent different disease entities. This study explored the time trends over a 23-year period in colorectal cancer incidence at various subsites by sex and age group. Data on the incidence of colorectal cancer were obtained from a population-based cancer registry in Shanghai, People's Republic of China. Between 1972 and 1994, 30,693 patients with colorectal cancer were registered at the Shanghai Cancer Registry. The overall age-adjusted colorectal cancer incidence rates increased > 50%, or 2% per year from 1972-1977 to 1990-1994, from 14 to 22 per 100,000 among men and from 12 to 19 per 100,000 among women. The increases in rates were considerably more rapid for colon cancer, with rates approximately doubling, than they were for rectal cancer. Proximal colon cancer was more common than distal colon cancer over the whole study period, whereas rates for both cancers rose with similar annual percentage changes (> 5% per year) and across virtually all age groups. The estimated annual increases rose from 2% at ages 35-44 years to 7% at ages 75-84 years for proximal colon cancer, but they were more uniform for distal colon cancer (5-6% per year). Age-adjusted and age-specific rectal cancer rates changed little. The male:female age-adjusted rate ratio for colorectal cancer was 1.19 in 1990-1994. The ratios increased over time and varied by subsites, with ratios increasing from the proximal colon to the distal colon and to the rectum. Furthermore, men had higher rates than women for distal colon and rectal cancers at ages 55 and older, whereas women had higher rates than men at younger ages for these two cancers. Male:female rate ratios for proximal colon cancer did not vary substantially with age. The findings from this study indicate that subsite-specific incidence rates of colorectal cancer differ by sex and age and in their time trends. Cancers arising in the proximal colon, distal colon, and rectum may have somewhat different disease etiologies.     

A model for the effect of cigarette smoking on lung cancer incidence in Connecticut

Population based data on smoking history derived from NCHS surveys were used to develop a model for lung cancer incidence in Connecticut. Trends in smoking prevalence suggest that, while the prevalence in men increased earlier than women, more male smokers have quit than their female counterparts. These trends in smoking prevalence suggest striking gender differences in a period effect for the smoking prevalence. Estimates of the proportion of current smokers, ex-smokers, and the mean duration of smoking were used in a model for the lung cancer incidence rates. The form for the relationship between smoking history and the incidence rate for these subgroups was based on information from cohort studies. The models represented a mixture of the smoking subgroups where the effect of smoking was considered to be either a multiplicative effect on the underlying age distribution, or a separate effect in which the level of exposure was the sole contribution to risk among smokers. The multiplicative model explained more than 80 per cent of the deviance for the period and cohort effects, while the non-multiplicative model could only account for trends in females. Hence, these results suggest that a sizeable portion of the period and cohort contributions to the lung cancer incidence trends in Connecticut can be attributed to the multiplicative model that utilizes this smoking information, although the lack of more detailed information is a limiting factor in developing the model.     

Diagnosing colorectal carcinoma: clinical and molecular approaches

In summary, the ability to decrease the mortality of colorectal carcinoma is increasingly within the grasp of clinicians. With accurate family and personal history, it is possible to estimate the risk of colorectal cancer and initiate FOBT and colonoscopy where appropriate. In the future, germline and even somatic genetic testing will further increase our ability to diagnose cancers before they become widely invasive. As molecular biology unravels the cause of what currently appears to be the majority of sporadic cancers, it may be possible to characterize more colorectal cancers that are caused by novel, as yet not recognized mutator genes. Unfortunately, a set of patients is likely to exist who remain to be diagnosed by symptoms caused by advanced cancer. The goal for the clinician is to decrease this subset to as small a group as possible.