Dietary and nutritional factors and pancreatic cancer: a case-control study based on direct interviews

Diabetes and its relationship to pancreatic carcinoma

INTRODUCTION

The mechanism of impaired glucose metabolism that develops in most patients with pancreatic cancer (PC) is obscure and the association between PC and diabetes is controversial. According to the published data, about 70% of patients with PC have an impaired glucose tolerance (IGT) or frank diabetes, whereas 30% do not. Up to 60% of the patients with IGT or diabetes show improvement in glucose metabolism after surgery, whereas other patients show only mild or no improvement.

AIM

To investigate our theory that there are three types of PC: 1) PC not associated with IGT or diabetes (IGT- subtype, approximately 20-30%); 2) PC associated with IGT or diabetes (IGT+ subtype, approximately 70-80%), in which the abnormality improves postoperatively (IGT+/- subtype, approximately 40-60%); or 3) PC associated with IGT or diabetes that does not improve after the tumor resection (IGT+/+ subtype, approximately 40-60%).

METHODOLOGY AND RESULTS

The review of the literature and our own experience, which is the subject of this article, suggests that the reason for impaired glucose metabolism in most patients is the alteration of islet cells, from which, in our view, cancer cells develop. There is a good possibility that the altered islet cells, and/or tumors derived from them, produce diabetogenic substances. The extent of the islet alteration (i.e., focal or diffuse) may determine whether the removal of the tumor alone can improve the metabolic alteration.

CONCLUSION

The elucidation of the mechanism is of immense importance for providing an early tumor marker and for developing preventative and therapeutic modalities.

Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adults

BACKGROUND

The influence of excess body weight on the risk of death from cancer has not been fully characterized.

METHODS

In a prospectively studied population of more than 900,000 U.S. adults (404,576 men and 495,477 women) who were free of cancer at enrollment in 1982, there were 57,145 deaths from cancer during 16 years of follow-up. We examined the relation in men and women between the body-mass index in 1982 and the risk of death from all cancers and from cancers at individual sites, while controlling for other risk factors in multivariate proportional-hazards models. We calculated the proportion of all deaths from cancer that was attributable to overweight and obesity in the U.S. population on the basis of risk estimates from the current study and national estimates of the prevalence of overweight and obesity in the U.S. adult population.

RESULTS

The heaviest members of this cohort (those with a body-mass index [the weight in kilograms divided by the square of the height in meters] of at least 40) had death rates from all cancers combined that were 52 percent higher (for men) and 62 percent higher (for women) than the rates in men and women of normal weight. For men, the relative risk of death was 1.52 (95 percent confidence interval, 1.13 to 2.05); for women, the relative risk was 1.62 (95 percent confidence interval, 1.40 to 1.87). In both men and women, body-mass index was also significantly associated with higher rates of death due to cancer of the esophagus, colon and rectum, liver, gallbladder, pancreas, and kidney; the same was true for death due to non-Hodgkin's lymphoma and multiple myeloma. Significant trends of increasing risk with higher body-mass-index values were observed for death from cancers of the stomach and prostate in men and for death from cancers of the breast, uterus, cervix, and ovary in women. On the basis of associations observed in this study, we estimate that current patterns of overweight and obesity in the United States could account for 14 percent of all deaths from cancer in men and 20 percent of those in women.

CONCLUSIONS

Increased body weight was associated with increased death rates for all cancers combined and for cancers at multiple specific sites.

Epidemiology of pancreatic cancer in Japan: a nested case-control study from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC)

BACKGROUND

To clarify lifestyle factors that affect the risk of pancreatic cancer among the Japanese population, a nested case-control study was conducted using data from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center (HERPACC), Japan.

METHODS

The study subjects included 200 incident cases of pancreatic cancer and 2000 age-class frequency-matched cancer-free outpatients attending the baseline questionnaire of HERPACC in the period 1988-1999. Associations between lifestyles and the risk of pancreatic cancer were evaluated using odds ratios estimated by the unconditional logistic regression model, adjusting for potential confounding factors.

RESULTS

A positive family history of pancreatic cancer and a past or present history of diabetes significantly increased the risk of pancreatic cancer. In contrast, regular physical exercise, a regular bowel habit, and frequent consumption of raw vegetables appeared to be protective. Current alcohol drinkers showed decreased risk, but the opposite was the case for former drinkers. Current smoking did not affect the risk of pancreatic cancer, while former smokers showed a tendency for decreased risk. Compared with light smokers, heavy smokers showed a modest tendency for increase in risk, especially those who starting smoking at a younger age, but there were no clear tendencies for duration and pack-years of smoking.

CONCLUSIONS

From these results it appears that smoking habit, which has long been considered a sole important determinant, has only a modest role, if any, in pancreatic cancer in Japanese.

Clinicopathologic analysis of pancreatic adenocarcinoma in African Americans and Caucasians

INTRODUCTION

African Americans have a higher incidence of pancreatic adenocarcinoma than do Caucasians for unknown reasons. Whether other clinicopathologic differences exist between these two groups is not known. This study was undertaken to compare the clinical, pathologic, and biologic findings for a group of patients with a histologic diagnosis of pancreatic ductal adenocarcinoma of the usual type in a single institution.

METHODOLOGY

We studied 410 patients (166 African Americans and 244 Caucasians) with a histologic diagnosis of pancreatic ductal adenocarcinoma of the usual type and analyzed (a) the clinicopathologic characteristics of the tumors, (b) the immunohistochemical expression of biomarkers implicated in pancreatic carcinogenesis (Fas, Fas ligand, HER2, p21/waf-1, p27, and p53), and (c) the presence and types of K- mutations at codon 12 as determined by polymerase chain reaction-mediated amplification. All elements of data were not available for all patients.

RESULTS

African Americans had significantly higher rates of K-ras mutations to valine than did Caucasians (58% versus 22%, respectively; p = 0.015) and were less likely to have received chemotherapy (45% versus 70%, respectively; p = 0.001) or radiation therapy (34% versus 57%, respectively; p = 0.003). African Americans also had more frequent positive surgical margins than did Caucasians (56% versus 25%, respectively; p = 0.001), although mean tumor size was similar between the two groups (African Americans, 3.4 cm; Caucasians, 3.5 cm). Other clinicopathologic variables were similar between the two groups, including median survival (African Americans, 8.5 months; Caucasians, 10.1 months), 5-year survival (African Americans, 3%; Caucasians, 6%), and stage at presentation. Differences in biomarker immunoreactivity included less frequent Fas expression (4% versus 24%, respectively; p = 0.048) and a trend toward more frequent strong HER2 expression (39% versus 18%, respectively p = 0.11) in African Americans than in Caucasians.

CONCLUSION

Although African American and Caucasian patients had similar survival rates associated with usual type pancreatic ductal adenocarcinoma, there were differences in management and expression of biologic markers between these two groups. African Americans were significantly less likely to receive radiation therapy or chemotherapy than were Caucasians, which may assume more importance as treatment improves. At the molecular level, African Americans had more frequent K- mutations to valine than did Caucasians.

Why do Black Americans have a higher risk of pancreatic cancer than White Americans?

BACKGROUND

For several decades, the incidence of pancreatic cancer has been 50% to 90% higher among blacks than among whites in the United States. The purpose of this study was to identify risk factors that may contribute to this racial disparity.

METHODS

We conducted a population-based case-control study of pancreatic cancer diagnosed in Atlanta (GA), Detroit (MI), and 10 New Jersey counties from August 1986 through April 1989. In-person interviews were exclusively with subjects (526 cases and 2153 population controls), rather than with next of kin.

RESULTS

The determinants of the higher incidence of pancreatic cancer among blacks than among whites differed by sex. Among men, established risk factors (, cigarette smoking, long-term diabetes mellitus, family history of pancreatic cancer) account for 46% of the disease in blacks and 37% in whites, potentially explaining all but 6% of the excess risk among blacks. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption (>7 drinks per week) and elevated body mass index (above the first quartile). When these less accepted risk factors were combined with the established risk factors, 88% of the disease in black women and 47% in white women were explained, potentially accounting for all of the excess risk among blacks in our female study population.

CONCLUSIONS

Among men, the established risk factors (mainly cigarette smoking and diabetes mellitus) explain almost the entire black/white disparity in incidence. Among women, however, other factors appear to contribute to the racial disparity, notably moderate/heavy alcohol consumption and elevated body mass index. In the absence of these factors, pancreatic cancer incidence rates among blacks probably would not exceed those among whites of either sex.

Gene-environment interactions in pancreatic cancer

Exocrine pancreatic cancer remains a major cause of cancer death in Western populations. Despite many efforts, little is known about its etiology. Tobacco is the only established cause, although the proportion of cases of exocrine pancreatic cancer attributed to it is only 30%. A family history of pancreatic cancer accounts for 10% of the cases of this disease. A large proportion of cases are due to yet unrecognized factors. The combined contribution of genetic susceptibility and environmental factors has rarely been considered. A higher risk of exocrine pancreatic cancer has been observed for patients with hereditary pancreatitis who smoked. It has also been suggested that CFTR mutations and alcohol could interact in the development of exocrine pancreatic cancer. Common variants in a large number of genes could act as low-penetrance alleles. Little is known about their role as susceptibility markers for exocrine pancreatic cancer, except for metabolic enzymes. A few studies have assessed the association between polymorphisms in these genes and exocrine pancreatic cancer. Surprisingly, none of them observed an interaction with tobacco consumption. The reality may be more complex; exocrine pancreatic cancer is genetically heterogeneous and it could involve many somatic and heritable mutations. Gene-gene interactions and endogenous factors, among others, can contribute to tumor development. Future epidemiological studies should consider all of these aspects together.

Pancreatitis as a risk for pancreatic cancer

Chronic pancreatitis clearly predisposes to pancreatic cancer, with early onset-long duration chronic pancreatitis from cystic fibrosis, TP, and HP conferring the highest risk. Chronic pancreatitis is not a critical step, however, but rather one of several conditions that accelerate the accumulation of critical genetic mutations and chromosomal losses necessary for carcinogenesis. Indeed, other germline mutations, environmental factors such as tobacco smoking and alcohol consumption, or dietary factors may also accelerate the pathway to carcinogenesis, and may be synergistic with the conditions created by chronic pancreatitis. Because patients with chronic pancreatitis are at high risk of pancreatic cancer, the physician is faced with decisions on how to manage this risk. Discontinuing smoking and alcohol consumption, and perhaps dietary modification are obvious recommendations for risk reduction. If, however, the patient is older and already in a very high-risk category (e.g., long-standing HP), then screening for cancers must be considered. Inclusion in multicenter trials is recommended, and information on ongoing studies can be obtained through the office of Dr. Whitcomb, or as posted on www.pancreas.org.

Epidemiologic and etiologic factors of pancreatic cancer

Ranking fourth as a cause of death from cancer for men and women in the United States, pancreatic cancer represents a significant challenge for physicians and surgeons. In addition to the elderly, high-risk groups include blacks, men, smokers, and patients with certain preexisting diseases such as pancreatitis and long-standing diabetes. Various inherited genetic disorders cause approximately 5% to 10% of the total cases of pancreatic cancer. Smoking doubles the risk of pancreatic cancer. Control of smoking offers the best available strategy for reducing the incidence of this disease. Dietary measures to reduce the risk of pancreatic cancer include maintenance of normal body weight and consumption of a well balanced diet with adequate amounts of fruits and vegetables. Chronic pancreatitis caused by heavy alcohol consumption or, rarely, by an underlying inherited disorder is another strong risk factor, but because this benign disease is uncommon, elimination of this underlying cause would have minimal impact on the frequency of pancreatic cancer.

Physical activity, anthropometric factors and risk of pancreatic cancer: results from the Canadian enhanced cancer surveillance system

To explore the hypothesis that insulin resistance may be an etiologic factor in pancreatic cancer, we assessed the pancreatic cancer risk associated with anthropometric factors and physical activity, both of which are important determinants of insulin sensitivity in humans. Three hundred and twelve patients with histologically confirmed pancreatic cancer were compared to 2,919 controls in a population-based, case-control study in 7 of the 10 Canadian provinces. Participants were asked to report their exposure status for the period 2 years before interview. Men in the highest quartile of body mass index (BMI, > or =28.3 kg/m(2)) were at increased risk of pancreatic cancer [adjusted odds ratio (OR) = 1.90, 95% confidence interval (CI) 1.08-3.35]. In addition, men who reported a decrease in weight of at least 2.9% from their lifetime maximum were at reduced risk compared to those reporting a < or =2.9% loss (> or =10.2% loss, OR = 0.51, 95% CI 0.30-0.86). BMI 2 years before interview was not associated with pancreatic cancer risk among women, though those reporting a > or =12.5% decrease in weight from their lifetime maximum had substantially lower risk compared to those in the baseline quartile (OR = 0.53, 95% CI 0.29-0.99). After adjustment for age, province of residence, dietary intake and anthropometric factors, men in the highest quartile of the composite moderate and strenuous physical activity index were at reduced risk of pancreatic cancer (OR = 0.53, 95% CI 0.31-0.90). Physical activity did not appear to be associated with pancreatic cancer among women, though a tendency for reduced risk with increasing levels of strenuous activity was suggested (p for trend = 0.06). Our findings support the hypothesis that insulin resistance is an etiologic factor in the development of pancreatic neoplasms among men and possibly women.

Promoting effect of a high-fat/high-protein diet in DMBA-induced ductal pancreatic cancer in rats

OBJECTIVE

To investigate whether a high-fat/high-protein diet (HFPD) acts as a promoter of the natural course of cancer growth in the 7,12-dimethylbenzanthracene (DMBA)-induced ductal pancreatic cancer model in rats.

SUMMARY BACKGROUND DATA

DMBA implantation to the rat pancreas induces ductal adenocarcinoma. Information regarding the effects of diet and the presence of K-ras mutation in this model is not available.

METHODS

Rats were randomly assigned to regular rat chow or a diet with a 30% content in fat and protein (HFPD). The presentation of cancer, the histologic spectrum of neoplasia at 1 and 9 months, and the prevalence of cancer in relation to diet were assessed. Histologic specimens comprising normal ducts, hyperplasia, dysplasia/carcinoma in situ, or carcinoma were designated by a pathologist and microdissected. Genomic DNA was extracted, and K-ras and H-ras gene mutations were determined by a mutant-enriched polymerase chain reaction assay and direct sequencing.

RESULTS

Rats fed HFPD increased their weight significantly compared with controls. DMBA induced characteristic stages of neoplasia at the implant site but not elsewhere. Macroscopic cancers of the pancreatic head presented regularly with common bile duct and gastric outlet obstruction. The prevalence of K-ras mutations was proportional to the degree of epithelial abnormality. K-ras mutations were significantly more frequent in cancer than in normal and hyperplastic ducts. H-ras mutations were not found. At 1 month in the HFPD-fed rats, the prevalence of cancer (16%) and dysplasia (16%) was not significantly different from the prevalence of cancer (29%) and dysplasia (8%) in the chow-fed rats. At 9 months the prevalence of cancer in the HFPD-fed rats increased to 29%, whereas that in the chow-fed rats decreased to 17%. The combined prevalence of cancer and dysplasia at 9 months in the HFPD-fed rats (34%) significantly exceeded that in the chow-fed rats.

CONCLUSIONS

DMBA induces characteristic stages of neoplasia in the evolution of ductal pancreatic cancer in rats. K-ras mutations occur progressively in the ladder of oncogenesis, as in human pancreatic neoplasms. The addition of a diet with a high fat and protein content acts as a promoter of carcinogenesis, possibly by interfering with repair mechanisms and natural regression of early lesions.

Dietary and other methyl-group availability factors and pancreatic cancer risk in a cohort of male smokers

The authors examined prospectively whether dietary folate and other factors known to influence methyl-group availability were associated with the development of exocrine pancreatic cancer within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study cohort. Of the 27,101 healthy male smokers aged 50--69 years who completed a self-administered dietary questionnaire at baseline, 157 developed pancreatic cancer during up to 13 years of follow-up from 1985 to 1997. Cox proportional hazards models were used to estimate the hazards ratios and 95% confidence intervals. The adjusted hazards ratio comparing the highest with the lowest quintile of dietary folate intake was 0.52 (95% confidence interval: 0.31, 0.87; p-trend = 0.05). Dietary methionine, alcohol intake, and smoking history did not modify this relation. No significant associations were observed between dietary methionine, vitamins B(6) and B(12), or alcohol intake and pancreatic cancer risk. Consistent with prior studies, this study shows that cigarette smoking was associated with an increased risk (highest compared with lowest quintile, cigarettes per day: hazards ratio = 1.82; 95% confidence interval: 1.10, 3.03; p-trend = 0.05). These results support the hypothesis that dietary folate intake is inversely associated with the risk of pancreatic cancer and confirm the risk associated with greater cigarette smoking.

Prevention of pancreatic cancer induction in hamsters by metformin

BACKGROUND AND AIMS

Our previous study suggested that the known promotional effect of a high fat diet, which in hamsters induces peripheral insulin resistance, is related to a compensatory proliferation of islet cells. The present study was to examine whether the prevention of islet cell proliferation can inhibit the promotional effect of a high-fat diet in pancreatic carcinogenesis.

METHODS

Two groups of high fat-fed hamsters were used. One group received Metformin in drinking water for life (HF+Met group), and the other group served as a control (HF group). At the time when the normalization of the plasma insulin level was expected, all hamsters were treated with the pancreatic carcinogen, N-nitrosobis-(2-oxopropyl)amine, and the experiment was terminated 42 weeks later.

RESULTS

Although 50% of the hamsters in the high-fat group developed malignant lesions, none was found in the HF+Met group (P < 0.05). Also, significantly more hyperplastic and premalignant lesions, most of which were found within the islets, were detected in the high-fat group (8.6 lesions/hamster) than in the HF+Met group (1.8 lesions/hamster).

CONCLUSIONS

The results lend further support on the significant role of islet cells in pancreatic carcinogenesis and may explain the association between pancreatic cancer and obesity, which is usually associated with peripheral insulin resistance.

Energy balance and cancer: the role of insulin and insulin-like growth factor-I

Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, 1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.

Risk factors for pancreatic cancer: a case-control study based on direct interviews

The etiology of pancreatic cancer is poorly understood, partly because of the inconsistency of findings among case-control studies of pancreatic cancer. Because of the unfavorable prognosis for pancreatic cancer, many case-control studies have been based largely on interviews with next of kin, who are known to report less reliable information on potential risk factors than original respondents. The purpose of this study was to estimate the effects of speculative risk factors such as dietary/nutritional factors and alcohol drinking, as well as those of established risk factors such as cigarette smoking, diabetes mellitus, and family history of pancreatic cancer, on pancreatic cancer risk based solely on direct interviews. This investigation was a population-based case-control study of pancreatic cancer diagnosed in Atlanta (GA), Detroit (MI), and ten New Jersey counties from August 1986 through April 1989. Direct interviews were conducted with 526 incident cases and 2,153 population controls. This study revealed a significant interaction between body mass index and caloric intake that was consistent by both race and gender. Subjects with elevated body mass index and caloric intake had increased risk, whereas those with elevated values for one of these factors but not the other experienced no increased risk. This finding suggests that energy balance may play a major role in pancreatic carcinogenesis. Diabetes mellitus was also a risk factor for pancreatic cancer, as well as a possible complication of the tumor. Our data are consistent with a key role for hyperinsulinemia in pancreatic carcinogenesis, particularly among non-diabetics with an elevated body mass index. A three-fold risk of pancreatic cancer among first-degree relatives of affected individuals was apparent. An increased risk also was associated with a family history of colon, endometrial, ovary, and breast cancer, suggesting a possible link to hereditary non-polyposis colon cancer. Our findings support a causal role for cigarette smoking in pancreatic carcinogenesis. Alcohol drinking at levels typically consumed by the general population of the United States did not appear to be a risk factor for pancreatic cancer, although heavy drinking may be related to risk, particularly in blacks.

Dietary factors and cancer risk

OBJECTIVES

To discuss the relationship between dietary factors and cancer risk reduction, the status of prevention trials in progress, and current dietary recommendations.

DATA SOURCES

Published research and review articles, medical books, and web sites.

CONCLUSIONS

Evidence indicates that dietary factors can reduce the risk of developing cancer. The dietary recommendations for cancer risk reduction are consistent with those for prevention of other chronic diseases and are thus useful for the majority of the population.

IMPLICATIONS FOR NURSING PRACTICE

In their role as educators, it is essential for nurses to provide accurate and timely information on diet and cancer risk reduction to their patients and the public and to encourage compliance with dietary recommendations.

Association between coffee drinking and K-ras mutations in exocrine pancreatic cancer. PANKRAS II Study Group

STUDY OBJECTIVE

To analyse the relation between coffee consumption and mutations in the K-ras gene in exocrine pancreatic cancer.

DESIGN

Case-case study. Consumption of coffee among cases with the activating mutation in the K-ras gene was compared with that of cases without the mutation.

SETTING AND PATIENTS

All cases of pancreatic cancer newly diagnosed at five hospitals in Spain during three years were included in the PANKRAS II Study (n = 185, of whom 121 whose tissue was available for molecular analysis are the object of the present report). Over 88% were personally interviewed in hospital. DNA was amplified from paraffin wax embedded tissues, and mutations in codon 12 of K-ras were detected by the artificial RFLP technique.

MAIN RESULTS

Mutations were found in tumours from 94 of 121 patients (77.7%). Mutations were more common among regular coffee drinkers than among non-regular coffee drinkers (82.0% v 55.6%, p = 0.018, n = 107). The odds ratio adjusted by age, sex, smoking and alcohol drinking was 5.41 (95% CI 1.64, 17.78). The weekly intake of coffee was significantly higher among patients with a mutated tumour (mean of 14.5 cups/week v 8.8 among patients with a wild type tumour, p < 0.05). With respect to non-regular coffee drinkers, the odds ratio of a mutated tumour adjusted by age, sex, smoking and alcohol drinking was 3.26 for drinkers of 2-7 cups/week, 5.77 for drinkers of 8-14 cups/week and 9.99 for drinkers of > or = 15 cups/week (p < 0.01, test for trend).

CONCLUSIONS

Pancreatic cancer cases without activating mutations in the K-ras gene had drank significantly less coffee than cases with a mutation, with a significant dose response relation: the less they drank, the less likely their tumours were to harbour a mutation. In exocrine pancreatic cancer the K-ras gene may be activated less often among non-regular coffee drinkers than among regular drinkers. Caffeine, other coffee compounds or other factors with which coffee drinking is associated may modulate K-ras activation.

Diabetes mellitus, other medical conditions and familial history of cancer as risk factors for pancreatic cancer

In a population-based case-control study of pancreatic cancer conducted in three areas of the USA, 484 cases and 2099 controls were interviewed to evaluate the aetiologic role of several medical conditions/interventions, including diabetes mellitus, cholecystectomy, ulcer/gastrectomy and allergic states. We also evaluated risk associated with family history of cancer. Our findings support previous studies indicating that diabetes is a risk factor for pancreatic cancer, as well as a possible complication of the tumour. A significant positive trend in risk with increasing years prior to diagnosis of pancreatic cancer was apparent (P-value for test of trend = 0.016), with diabetics diagnosed at least 10 years prior to diagnosis having a significant 50% increased risk. Those treated with insulin had risks similar to those not treated with insulin (odds ratio (OR) = 1.6 and 1.5 respectively), and no trend in risk was associated with increasing duration of insulin treatment. Cholecystectomy also appeared to be a risk factor, as well as a consequence of the malignancy. Subjects with a cholecystectomy at least 20 years prior to the diagnosis of pancreatic cancer experienced a 70% increased risk, which was marginally significant. In contrast, subjects with a history of duodenal or gastric ulcer had little or no elevated risk (OR = 1.2; confidence interval = 0.9-1.6). Those treated by gastrectomy had the same risk as those not receiving surgery, providing little support for the hypothesis that gastrectomy is a risk factor for pancreatic cancer. A significant 40% reduced risk was associated with hay fever, a non-significant 50% decreased risk with allergies to animals, and a non-significant 40% reduced risk with allergies to dust/moulds. These associations, however, may be due to chance since no risk reductions were apparent for asthma or several other types of allergies. In addition, we observed significantly increased risks for subjects reporting a first-degree relative with cancers of the pancreas (OR = 3.2), colon (OR = 1.7) or ovary (OR = 5.3) and non-significantly increased risks for cancers of the endometrium (OR = 1.5) or breast (OR = 1.3). The pattern is consistent with the familial predisposition reported for pancreatic cancer and with the array of tumours associated with hereditary non-polyposis colon cancer.