Physical activity, body weight, and pancreatic cancer mortality

Diabetes Mellitus, Obesity, and Risk of Pancreatic Ductal Adenocarcinoma: a Large Case-Control Study from Iran

BACKGROUND

Pancreatic cancer (PC) is a deadly, globally increasing cancer. The causes of PC are still insufficiently known, however smoking, diabetes mellitus (DM), and obesity have been identified as risk factors of PC, mostly in the developed countries. We evaluated these risk factors and their contribution to PC among an Iranian population.

METHODS

Cases and controls were selected from patients who were registered to a tertiary gastrointestinal diseases referral hospital in Tehran, Iran, from Jan 2012 to Jan 2018. Information on risk factors was collected by personal interview using a structured questionnaire. Logistic regression models were used to calculate adjusted odds ratios (AORs) and 95% confidence intervals (CIs).

RESULTS

We recruited 470 new patients with histopathological PC diagnosis and 526 sex and age-matched controls. Cigarette-smoking [AOR: 1.65 (1.15-2.38)], opium use [AOR: 1.58 (1.06-2.35)], DM [AOR: 1.99 (1.31-3.02)], and having a history of any cancer in a first-degree family member [AOR: 1.53 (1.14-2.05)] were associated with an increased risk of PC. We did not find an association between obesity [AOR: 0.99 (0.71-1.38)] and PC. Approximately 4.6%, 5.9%, 8.2%, and 10.9% risk of PC were related to cigarette-smoking, opium use, DM, and family history of any cancer, respectively.

CONCLUSION

This study supports that DM is associated with PC risk; however, similar to many studies in Asia, obesity is not associated with PC in Iranians. DM has the highest impact on PC development in Iranian women.

Physical activity and sedentary behaviour over adulthood in relation to all-cause and cause-specific mortality: a systematic review of analytic strategies and study findings

BACKGROUND

Questions remain about the effect on mortality of physical activity and sedentary behaviour over time. We summarized the evidence from studies that assessed exposure from multiple time points and critiqued the analytic approaches used.

METHODS

A search was performed on MEDLINE, Embase, Emcare, Scopus and Web of Science up to January 2021 for studies of repeatedly assessed physical activity or sedentary behaviour in relation to all-cause or cause-specific mortality. Relative risks from individual studies were extracted. Each study was assessed for risk of bias from multiple domains.

RESULTS

We identified 64 eligible studies (57 on physical activity, 6 on sedentary behaviour, 1 on both). Cox regression with a time-fixed exposure history (n = 45) or time-varying covariates (n = 13) were the most frequently used methods. Only four studies used g-methods, which are designed to adjust for time-varying confounding. Risk of bias arose primarily from inadequate adjustment for time-varying confounders, participant selection, exposure classification and changes from measured exposure. Despite heterogeneity in methods, most studies found that being consistently or increasingly active over adulthood was associated with lower all-cause and cardiovascular-disease mortality compared with being always inactive. Few studies examined physical-activity changes and cancer mortality or effects of sedentary-behaviour changes on mortality outcomes.

CONCLUSIONS

Accumulating more evidence using longitudinal data while addressing the methodological challenges would provide greater insight into the health effects of initiating or maintaining a more active and less sedentary lifestyle.

Physical Activity and Mortality in Cancer Survivors: A Systematic Review and Meta-Analysis

Background

Recommendations for improved survival after cancer through physical activity (PA) exist, although the evidence is still emerging. Our primary objective was to conduct a systematic review and meta-analysis of the association between prediagnosis and postdiagnosis PA and survival (cancer-specific, all-cause, and cardiovascular disease mortality) for all cancers and by tumor site. Secondary objectives were to examine the associations within population subgroups, by PA domain, and to determine the optimal dose of PA related to survival.

Methods

PubMed, EMBASE, and SportsDiscus databases were searched from inception to November 1, 2018. DerSimonian-Laird random-effects models were used to estimate the summary hazard ratios (HRs) and 95% confidence intervals (CI) for primary and secondary analyses and to conduct dose-response analyses.

Results

Evidence from 136 studies showed improved survival outcomes with highest vs lowest levels of prediagnosis or postdiagnosis total or recreational PA for all-cancers combined (cancer specific mortality: HR = 0.82, 95% CI = 0.79 to 0.86, and HR = 0.63, 95% CI = 0.53 to 0.75, respectively) as well as for 11 specific cancer sites. For breast and colorectal cancers, greater reductions were observed for postdiagnosis PA (HR = 0.58–0.63) compared with prediagnosis PA (HR = 0.80–0.86) for cancer-specific and all-cause mortality. Survival benefits through PA were observed in most subgroups (within sex, body mass index, menopausal status, colorectal subtypes, and PA domain) examined. Inverse dose-response relationships between PA and breast cancer-specific and all-cause mortality were observed, with steep reductions in hazards to 10–15 metabolic equivalent hours per week.

Conclusion

Higher prediagnosis and postdiagnosis levels of PA were associated with improved survival outcomes for at least 11 cancer types, providing support for global promotion of PA guidelines following cancer.

Physical Activity and Pancreatic Cancer Risk among Urban Chinese: Results from Two Prospective Cohort Studies

Background: Associations between physical activity and pancreatic cancer risk are unclear.Methods: In two prospective cohort studies, the Shanghai Women's Health Study and Shanghai Men's Health Study, physical activity and other information were collected at the baseline interview of 72,451 women and 60,037 men. Participants were followed up through annual linkage with a cancer registry in combination with in-person interviews taking place every 2 to 4 years.Results: We identified 225 female and 159 male cases during a median follow up of 16.1 and 10.3 years, respectively. Adult exercise participation was significantly associated with a decreased pancreatic cancer risk in men [hazard ratio (HR), 95% confidence interval (CI): 0.71 (0.50-1.00)]. Meeting the recommended minimum exercise threshold to achieve health benefits of 150 min/week of moderate-intensity or 75 min/week of vigorous-intensity exercise was associated with further decreased pancreatic cancer risk [HR (95% CI): 0.59 (0.40-0.87)]. We also observed an inverse association between adolescent physical activity and pancreatic cancer risk in men [HR (95% CI): 0.54 (0.33-0.90)]. Exercise throughout one's lifetime was associated with a 68% decrease in pancreatic cancer risk [HR (95% CI): 0.32 (0.16-0.66)]. No significant association was found in women. Adult non-exercise daily activity and occupational activity were not associated with pancreatic cancer risk in either men or women.Conclusions: Adult exercise and adolescent physical activity were significantly associated with a decreased pancreatic cancer risk in men but not in women.Impact: These findings underscore the importance of investigating the possible modification by sex on the exercise and pancreatic cancer risk association. Cancer Epidemiol Biomarkers Prev; 27(4); 479-87. ©2018 AACR.

Sex-specific effects of leisure-time physical activity on cause-specific mortality in NHANES III

Associations between leisure time physical activity (LTPA) and all-cause mortality seem quite strong, however, less is known about the association of LTPA and cause-specific mortality. To examine this association data from the Third National Health and Nutrition Examination Survey (NHANES III), including 15,307 individuals of the non-institutionalized civilian United States population, were used. Data were collected from 1988 to 1994 with a mortality follow-up until 2006. LTPA was assessed during home interviews in which participants specified their LTPA and the performed frequency during the past month. Cox proportional hazards regression models were applied to analyze the risk of cause-specific mortality regarding LTPA. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed. An inverse association of LTPA with CVD mortality was observed for men and women combined for irregular (HR 0.66; 95% CI 0.51-0.85), and for regular activity (HR 0.58; 95% CI 0.47-0.72). An inverse association of LTPA with CVD mortality was observed only in women for irregular (HR 0.64; 95% CI 0.49-0.84) and for regular activity (HR 0.55; 95% CI 0.43-0.72). In men, no significant associations were seen. For mortality caused by respiratory diseases, a decreased mortality was also observed in the combined group (men and women) but after separating according to sex a decreased mortality was only observed in women. No statistically significant association of LTPA with cancer mortality was observed. Our data support an inverse association between LTPA and CVD and respiratory disease mortality in women, but not in men, and no associations with cancer.

Pancreatic cancer risk in relation to sex, lifestyle factors, and pre-diagnostic anthropometry in the Malmö Diet and Cancer Study

Background

Lifestyle factors may influence the risk of developing pancreatic cancer. Whereas cigarette smoking is an established risk factor, the effects of high alcohol intake and obesity are more uncertain. The aim of the present study was to examine the associations of pre-diagnostic anthropometry, alcohol consumption, and smoking habits with pancreatic cancer risk in a Swedish prospective, population-based cohort, with particular reference to potential sex differences.

Methods

The studied cohort consists of 28,098 participants, including all incident cases of pancreatic cancer, in the Malmö Diet and Cancer Study up until December 31, 2013 (n = 163). Non-parametric and chi-squared tests were applied to compare the distribution of risk factors between cases and non-cases. Cox regression proportional hazards models were used to estimate the relationship between investigative factors and pancreatic cancer risk. Anthropometric factors included height, weight, body mass index (BMI), waist and hip circumference, waist-hip ratio (WHR), and body fat percentage.

Results

BMI was not a significant risk factor for pancreatic cancer, but a higher WHR was significantly associated with an increased risk in the entire cohort (hazard ratio (HR) 2.36, 95% confidence interval (CI) 1.28–4.35, p for trend = 0.009). Regular smoking was a significant risk factor among both women (HR 2.62, 95% CI 1.61–4.27) and men (HR 3.57, 95% CI 1.70–7.47), whereas occasional smoking was a significant risk factor only in women (HR 3.29, 95% CI 1.50–7.19). Passive smoking at work for >20 years was significantly associated with an increased risk in the entire cohort (HR 1.73, 95% CI 1.15–2.58) and in women selectively (HR 2.01, 95% CI 1.21–3.31). Alcohol consumption was not a significant risk factor. A significant interaction was found between female sex and age (p = 0.045), but no other factor, in relation to pancreatic cancer risk.

Conclusions

WHR was the only pre-diagnostic anthropometric factor associated with pancreatic cancer risk, with no sex-related differences. Regular smoking was confirmed as a significant risk factor in both sexes, whereas occasional and passive smoking were significant risk factors only in women. Despite the lack of a significant interaction between smoking and sex in relation with pancreatic cancer risk, potential sex differences should be considered in future epidemiological studies.

Premorbid Obesity and Mortality in Patients With Pancreatic Cancer: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Obesity is associated with an increased risk for pancreatic cancer, but it is unclear whether it affects mortality. We performed a systematic review and meta-analysis to assess the association between premorbid obesity and mortality from pancreatic cancer.

METHODS

We performed a systematic search through January 2015 and identified studies of the association between premorbid obesity (at least 1 year prior to pancreatic cancer diagnosis) and pancreatic cancer-related mortality. We estimated summary adjusted hazard ratio (aHR) with 95% confidence interval (CI), comparing data from obese (body mass index [BMI] ≥30 kg/m(2)) and overweight subjects (BMI, 25.0-29.9 kg/m(2)) with those from individuals with a normal BMI (controls) by using random-effects model.

RESULTS

We identified 13 studies (including 3 studies that pooled multiple cohorts); 5 studies included only patients with pancreatic cancer, whereas 8 studies evaluated pancreatic cancer-related mortality in cancer-free individuals at inception. In the meta-analysis, we observed increase in pancreatic cancer-related mortality among overweight (aHR, 1.06; 95% CI, 1.02-1.11; I(2) = 0) and obese individuals (aHR, 1.31; 95% CI, 1.20-1.42; I(2) = 43%), compared with controls; the association remained when we analyzed data from only subjects with pancreatic cancer. Each 1 kg/m(2) increase in BMI was associated with 10% increase in mortality (aHR, 1.10; 95% CI, 1.05-1.15) with minimal heterogeneity (I(2) = 0). In the subgroup analysis, obesity was associated with increased mortality in Western populations (11 studies; aHR, 1.32; 95% CI, 1.22-1.42) but not in Asia-Pacific populations (2 studies; aHR, 0.98; 95% CI, 0.76-1.27).

CONCLUSIONS

In a systematic review and meta-analysis, we associated increasing level of obesity with increased mortality in patients with pancreatic cancer in Western but not Asia-Pacific populations. Strategies to reduce obesity-induced metabolic abnormalities might be developed to treat patients with pancreatic cancer.

Leisure time physical activity and cancer risk: evaluation of the WHO's recommendation based on 126 high-quality epidemiological studies

BACKGROUND

The WHO has concluded that physical activity reduces the risk of numerous diseases. However, few systemic reviews have been performed to assess the role of leisure time physical activity (LTPA) in lowering the risk of cancer in a dose-dependent manner and furthermore the suitability of recommendation of physical activity by the WHO.

METHODS

A systematic review and meta-analysis was designed to estimate cancer risk by LTPA in binary comparison and in a dose-dependent manner. MEDLINE and Web of Science were searched up to 30 December 2014 without language restrictions. Reference lists were reviewed for potential articles.

RESULTS

A total of 126 studies were recruited into the meta-analysis. Overall, the total cancer risk was reduced by 10% in people who undertook the most LTPA as compared with those who did the least. Dose-response meta-analysis indicated that the current WHO recommendation (equal to an average of 10 metabolic equivalents of energy hours per week) induced a 7% (95% CI 5% to 9%) cancer reduction. Moreover, the protective role of LTPA against cancer becomes saturated at 20 metabolic equivalents of energy hours per week, with a relative risk of 0.91 (95% CI 0.88 to 0.93). Subanalyses results based on cancer types showed that LTPA only exhibited significant protection against breast cancer and colorectal cancer.

CONCLUSIONS

Our meta-analysis indicates that the current WHO recommendation of physical activity can result in a 7% reduction in cancer risk, which is mainly attributed to its protective role against breast cancer and colorectal cancer. Furthermore, two-fold of current recommendation level is considered to give its saturated protection against cancer.

Epidemiology of Pancreatic and Periampullary Cancer

Pancreatic cancer is an important public health problem, although infrequent but with an exceptionally high mortality rate worldwide. Given that the majority of cancers occur in association with smoking, diabetes, pancreatitis, genetic factors, and others and with a growing population worldwide in mind, more cases would be expected in the near future giving further impetus to investigating prevention and treatment strategies to this international issue. The representative data on epidemiology of carcinoma of pancreas in India and Nepal are very poor. While there are many questions to be resolved, it is apparent that many facets of pancreatic cancer are becoming increasingly understood, and prospects for prevention are becoming apparent. Hence, screening research, recommendations, and implementation is an obvious priority. Although previous studies have contributed to the knowledge of carcinoma of pancreas epidemiology, such association needs to be further verified with proper epidemiological work. A new and global approach to the study of carcinoma of pancreas epidemiology is required if the disease prevention and treatment strategies are to be adequately directed and supported in the coming years. The collection and analysis of epidemiologic carcinoma of pancreas data will play a critical role in guiding future disease prevention strategies and optimizing patient management.

A pooled analysis of body mass index and pancreatic cancer mortality in african americans

BACKGROUND

Pancreatic cancer is a leading cause of cancer-related mortality in the United States and both incidence and mortality are highest in African Americans. Obesity is also disproportionately high in African Americans, but limited data are available on the relation of obesity to pancreatic cancer in this population.

METHODS

Seven large prospective cohort studies pooled data from African American participants. Body mass index (BMI) was calculated from self-reported height and weight at baseline. Cox regression was used to calculate HRs and 95% confidence intervals (CI) for levels of BMI relative to BMI 18.5-24.9, with adjustment for covariates. Primary analyses were restricted to participants with ≥5 years of follow-up because weight loss before diagnosis may have influenced baseline BMI in cases who died during early follow-up.

RESULTS

In follow-up of 239,597 participants, 897 pancreatic cancer deaths occurred. HRs were 1.08 (95% CI, 0.90-1.31) for BMI 25.0 to 29.9, 1.25 (95% CI, 0.99-1.57) for BMI 30.0 to 34.9, and 1.31 (95% CI, 0.97-1.77) for BMI ≥35.0 among those with ≥5 years of follow-up (Ptrend = 0.03). The association was evident among both sexes and was independent of a history of diabetes. A stronger association was observed among never-smokers (BMI ≥30 vs. referent: HR = 1.44; 95% CI, 1.02-2.03) than among smokers (HR = 1.16; 95% CI, 0.87-1.54; Pinteraction = 0.02).

CONCLUSION

The findings suggest that obesity is independently associated with increased pancreatic cancer mortality in African Americans.

IMPACT

Interventions to reduce obesity may also reduce risk of pancreatic cancer mortality, particularly among never-smokers.

Physical activity and risk of pancreatic cancer in a central European multicenter case-control study

PURPOSE

Findings from epidemiological studies examining physical activity in relation to pancreatic cancer risk have suggested decreased risks for physical activity; however, the results are inconsistent.

METHODS

The association between occupational and leisure-time physical activity and risk of pancreatic cancer was examined among 826 pancreatic cancer cases and 930 age-, sex- and center-matched controls from a large multicenter central European study in Czech Republic and Slovakia recruited between 2004 and 2012. Data on physical activity including type and dose (frequency, intensity, and duration) were examined using multivariable-adjusted logistic regression models.

RESULTS

Occupational physical activity was not significantly associated with risk of pancreatic cancer [odds ratio (OR) 0.90, 95 % confidence interval (CI) 0.71-1.15]. A 35 % decrease in risk of pancreatic cancer was observed for regular leisure-time physical activity (OR 0.65, 95 % CI 0.52-0.87). The risk estimates were significant for low and moderate intensity of activity with the strongest protective effect among individuals who exercised during more than 40 weeks per year. The results for cumulated leisure-time physical activity assessed 1 year prior to diagnosis achieved the same level of risk reduction. In addition, stronger risk estimates for leisure-time physical activity were observed among women (men: OR 0.74, 95 % CI 0.54-1.01; women: OR 0.53, 95 % CI 0.37-0.75). The findings for female participants were stronger for intensity and frequency of leisure-time physical activity, in particular for light and moderate activity (OR 0.43, 95 % CI 0.25-0.75; and OR 0.57, 95 % CI 0.37-0.88, respectively).

CONCLUSION

These results provide evidence for a decreased risk of pancreatic cancer associated with regular leisure-time physical activity.

Obesity and pancreatic cancer

BACKGROUND

Pancreatic cancer is an invariably fatal malignancy. Cigarette smoking and diabetes are established risk factors, but over the last two decades studies have shown that excess adiposity is an additional independent risk factor with 30-50% of cases thought to be attributed to nutritional factors. The aim of this narrative review is to analyze all the epidemiological evidence on the topic and possible pathophysiology.

METHODS

We searched PubMed, Embase, Cochrane Library and Medline, and all available evidence was included. We firstly analyze meta- and pooled analysis. Then we discuss individual studies to identify sources of discrepancies between studies and attempt to delineate pathophysiology.

RESULTS

It is estimated that obese individuals have a relative risk (RR) ranging between 1.19 and 1.47, when compared with those of normal weight, regardless of diabetes or smoking status. No significant differences were found between gender.

CONCLUSION

There is a measurable increased risk of developing pancreatic cancer in obese individuals, and excess adiposity is related to the condition with a "dose-response" curve. Hyperinsulinemia and possibly hyperestrogenism secondary to a metabolic syndrome, and independently from diabetes status, appear to be the key elements of the pathogenesis in pancreatic cancer secondary to excess body fat. Increased efforts should therefore be made in tackling the epidemic levels of obesity in the Western world countries.

The pathobiological impact of cigarette smoke on pancreatic cancer development (review)

Despite extensive efforts, pancreatic cancer remains incurable. Most risk factors, such as genetic disposition, metabolic diseases or chronic pancreatitis cannot be influenced. By contrast, cigarette smoking, an important risk factor for pancreatic cancer, can be controlled. Despite the epidemiological evidence of the detrimental effects of cigarette smoking with regard to pancreatic cancer development and its unique property of being influenceable, our understanding of cigarette smoke-induced pancreatic carcinogenesis is limited. Current data on cigarette smoke-induced pancreatic carcinogenesis indicate multifactorial events that are triggered by nicotine, which is the major pharmacologically active constituent of tobacco smoke. In addition to nicotine, a vast number of carcinogens have the potential to reach the pancreatic gland, where they are metabolized, in some instances to even more toxic compounds. These metabolic events are not restricted to pancreatic ductal cells. Several studies show that acinar cells are also greatly affected. Furthermore, pancreatic cancer progenitor cells do not only derive from the ductal epithelial lineage, but also from acinar cells. This sheds new light on cigarette smoke-induced acinar cell damage. On this background, our objective is to outline a multifactorial model of tobacco smoke-induced pancreatic carcinogenesis.

Obesity and pancreatic cancer: overview of epidemiologic evidence and biologic mechanisms

In the United States, pancreatic cancer is characterized by a low 5-yr survival rate of approximately 6%, fewer than 10% of patients diagnosed with localized disease and thus candidates for "curative" surgical resection, increasing incidence and few established risk factors. Similar statistics are observed for other industrialized nations. With new evidence to suggest that pancreatic cancer develops over a number of years, markers that can better identify high risk patients and are applicable to earlier diagnosis hold promise for improving these dire statistics. Obesity is one of the few modifiable risk factors that has been associated with increased risk of pancreatic cancer and also is related to increased risk of diabetes, a condition that in turn has been associated with pancreatic cancer development. Given recent data that nearly 70% of United States adults are overweight or obese, a clarification of the complex association between obesity and pancreatic cancer may disclose targets for prevention and intervention to decrease incidence and improve prognosis of this highly fatal disease. An overview of the current epidemiology and hypothesized biological mechanisms involved in the obesity-pancreatic cancer association are presented.

A pooled analysis of 14 cohort studies of anthropometric factors and pancreatic cancer risk

Epidemiologic studies of pancreatic cancer risk have reported null or nonsignificant positive associations for obesity, while associations for height have been null. Waist and hip circumference have been evaluated infrequently. A pooled analysis of 14 cohort studies on 846,340 individuals was conducted; 2,135 individuals were diagnosed with pancreatic cancer during follow-up. Study-specific relative risks (RRs) and 95% confidence intervals (CIs) were calculated by Cox proportional hazards models, and then pooled using a random effects model. Compared to individuals with a body mass index (BMI) at baseline between 21-22.9 kg/m(2) , pancreatic cancer risk was 47% higher (95%CI:23-75%) among obese (BMI ≥ 30 kg/m(2) ) individuals. A positive association was observed for BMI in early adulthood (pooled multivariate [MV]RR = 1.30, 95%CI = 1.09-1.56 comparing BMI ≥ 25 kg/m(2) to a BMI between 21 and 22.9 kg/m(2) ). Compared to individuals who were not overweight in early adulthood (BMI < 25 kg/m(2) ) and not obese at baseline (BMI < 30 kg/m(2) ), pancreatic cancer risk was 54% higher (95%CI = 24-93%) for those who were overweight in early adulthood and obese at baseline. We observed a 40% higher risk among individuals who had gained BMI ≥ 10 kg/m(2) between BMI at baseline and younger ages compared to individuals whose BMI remained stable. Results were either similar or slightly stronger among never smokers. A positive association was observed between waist to hip ratio (WHR) and pancreatic cancer risk (pooled MVRR = 1.35 comparing the highest versus lowest quartile, 95%CI = 1.03-1.78). BMI and WHR were positively associated with pancreatic cancer risk. Maintaining normal body weight may offer a feasible approach to reducing morbidity and mortality from pancreatic cancer.

Body mass index, abdominal fatness and pancreatic cancer risk: a systematic review and non-linear dose-response meta-analysis of prospective studies

BACKGROUND

Questions remain about the shape of the dose-response relationship between body mass index (BMI) and pancreatic cancer risk, possible confounding by smoking, and differences by gender or geographic location. Whether abdominal obesity increases risk is unclear.

METHODS

We conducted a systematic review and meta-analysis of prospective studies of the association between BMI, abdominal fatness and pancreatic cancer risk and searched PubMed and several other databases up to January 2011. Summary relative risks (RRs) were calculated using a random-effects model.

RESULTS

Twenty-three prospective studies of BMI and pancreatic cancer risk with 9504 cases were included. The summary RR for a 5-unit increment was 1.10 [95% confidence interval (CI) 1.07-1.14, I(2) = 19%] and results were similar when stratified by gender and geographic location. There was evidence of a non-linear association, P(non-linearity) = 0.005; however, among nonsmokers, there was increased risk even within the 'normal' BMI range. The summary RR for a 10-cm increase in waist circumference was 1.11 (95% CI 1.05-1.18, I(2) = 0%) and for a 0.1-unit increment in waist-to-hip ratio was 1.19 (95% CI 1.09-1.31, I(2) = 11%).

CONCLUSIONS

Both general and abdominal fatness increases pancreatic cancer risk. Among nonsmokers, risk increases even among persons within the normal BMI range.

Anthropometric measures, body mass index, and pancreatic cancer: a pooled analysis from the Pancreatic Cancer Cohort Consortium (PanScan)

BACKGROUND

Obesity has been proposed as a risk factor for pancreatic cancer.

METHODS

Pooled data were analyzed from the National Cancer Institute Pancreatic Cancer Cohort Consortium (PanScan) to study the association between prediagnostic anthropometric measures and risk of pancreatic cancer. PanScan applied a nested case-control study design and included 2170 cases and 2209 control subjects. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using unconditional logistic regression for cohort-specific quartiles of body mass index (BMI [calculated as weight in kilograms divided by height in meters squared]), weight, height, waist circumference, and waist to hip ratio as well as conventional BMI categories (underweight, <18.5; normal weight, 18.5-24.9; overweight, 25.0-29.9; obese, 30.0-34.9; and severely obese, > or = 35.0). Models were adjusted for potential confounders.

RESULTS

In all of the participants, a positive association between increasing BMI and risk of pancreatic cancer was observed (adjusted OR for the highest vs lowest BMI quartile, 1.33; 95% CI, 1.12-1.58; P(trend) < .001). In men, the adjusted OR for pancreatic cancer for the highest vs lowest quartile of BMI was 1.33 (95% CI, 1.04-1.69; P(trend) < .03), and in women it was 1.34 (95% CI, 1.05-1.70; P(trend) = .01). Increased waist to hip ratio was associated with increased risk of pancreatic cancer in women (adjusted OR for the highest vs lowest quartile, 1.87; 95% CI, 1.31-2.69; P(trend) = .003) but less so in men.

CONCLUSIONS

These findings provide strong support for a positive association between BMI and pancreatic cancer risk. In addition, centralized fat distribution may increase pancreatic cancer risk, especially in women.

Can physical activity modulate pancreatic cancer risk? a systematic review and meta-analysis

Numerous epidemiological studies have examined the association between physical activity and pancreatic cancer; however, findings from individual cohorts have largely not corroborated a protective effect. Among other plausible mechanisms, physical activity may reduce abdominal fat depots inducing metabolic improvements in glucose tolerance and insulin sensitivity, thereby potentially attenuating pancreatic cancer risk. We performed a systematic review to examine associations between physical activity and pancreatic cancer. Six electronic databases were searched from their inception through July 2009, including MEDLINE and EMBASE, seeking observational studies examining any physical activity measure with pancreatic cancer incidence/mortality as an outcome. A random effects model was used to pool individual effect estimates evaluating highest vs. lowest categories of activity. Twenty-eight studies were included. Pooled estimates indicated a reduction in pancreatic cancer risk with higher levels of total (five prospective studies, RR: 0.72, 95% CI: 0.52-0.99) and occupational activity (four prospective studies, RR: 0.75, 95% CI: 0.59-0.96). Nonsignificant inverse associations were seen between risks and recreational and transport physical activity. When examining exercise intensity, moderate activity appeared more protective (RR: 0.79, 95% CI: 0.52-1.20) than vigorous activity (RR: 0.97, 95% CI: 0.85-1.11), but results were not statistically significant and the former activity variable incorporated marked heterogeneity. Despite indications of an inverse relationship with higher levels of work and total activity, there was little evidence of such associations with recreational and other activity exposures.

Physical activity, cognitive function, and mortality in a US national cohort

PURPOSE

Increasing physical activity is postulated to slow cognitive decline associated with aging. Low levels of both physical activity and cognitive function are associated with increased risk of mortality. We test the hypothesis that the relative protective effect of high physical activity level as related to mortality is greater in persons with impaired cognitive function than in others.

METHODS

Data were analyzed from a longitudinal mortality follow-up study of 5903 American men and women aged 60 years and older examined in 1988 to 1994 who were followed an average of 8.5 years. Measurements at baseline included self-reported leisure-time physical activity (LTPA), a short index of cognitive function (SICF), sociodemographic data, health status, and physical and biochemical measurements.

RESULTS

Death during follow-up occurred in 2431 persons. In bivariate cross-sectional analyses, more frequent LTPA was associated with greater cognitive function. In proportional hazards regression analysis, no significant interaction of LTPA with cognitive function was found; however, there was a significant age-LTPA interaction. After adjusting for confounding by baseline sociodemographic data and health status at ages 60 to 74, the hazards ratio (95% confidence intervals) was for LTPA more than 8 times weekly compared with none (0.51; 0.38-0.76, p < .001) and for low SICF score compared with high 1.43 (1.36; 1.00-1.84, p < .05). After controlling for health behaviors, blood pressure, and body mass, C-reactive protein, and high-density lipoprotein cholesterol, the LTPA hazards ratio was 0.52 (0.35-0.78; p = .002), but cognitive function was no longer significant. At ages 75 and older, results were similar for LTPA, but cognitive function remained significant after adjustment.

CONCLUSIONS

In a nationwide cohort of older Americans, analyses demonstrated a lower risk of death independent of confounders among those with frequent LTPA. Much of the effect of low cognitive function could be explained by other risk factors at ages 60 to 74 but not 75 years and older.

[Risk factors and early diagnosis of pancreatic cancer]

Pancreatic cancer (PC) is usually incurable. Identifying people at risk for developing PC may improve the prognosis of this entity. The main risk factors for PC are Peutz-Jeghers syndrome, hereditary pancreatitis and a history family of PC. Other factors, such as advanced age and smoking, should also be taken into account. PC screening is only useful in very high risk individuals. Tools that allow tumors to be identified in the early stages are required in order to apply appropriate curative treatments. In this scenario, only endoscopic ultrasound with cytological analysis of suspicious pancreatic lesions has proved to be useful.

Cardiorespiratory fitness and digestive cancer mortality: findings from the aerobics center longitudinal study

Although higher levels of physical activity are inversely associated with risk of colon cancer, few prospective studies have evaluated overall digestive system cancer mortality in relation to cardiorespiratory fitness (CRF). The authors examined this association among 38,801 men ages 20 to 88 years who performed a maximal treadmill exercise test at baseline in the Aerobics Center Longitudinal Study (Dallas, TX) during 1974 to 2003. Mortality was assessed over 29 years of follow-up (1974-2003). Two hundred eighty-three digestive system cancer deaths occurred during a mean 17 years of observation. Age-adjusted mortality rates per 10,000 person-years according to low, moderate, and high CRF groups were 6.8, 4.0, and 3.3 for digestive system cancer (P(trend) < 0.001). After adjustment for age, examination year, body mass index, smoking, drinking, family history of cancer, personal history of diabetes, hazard ratios (95% confidence intervals) for overall digestive cancer deaths for those in the middle and upper 40% of the distribution of CRF relative to those in the lowest 20% were 0.66 (0.49-0.88) and 0.56 (0.40-0.80), respectively. Being fit (the upper 80% of CRF) was associated with a lower risk of mortality from colon [0.61 (0.37-1.00)], colorectal [0.58 (0.37-0.92)], and liver cancer [0.28 (0.11-0.72)] compared with being unfit (the lowest 20% of CRF). These findings support a protective role of CRF against total digestive tract, colorectal, and liver cancer deaths in men.

Energy balance, physical activity, and cancer risk. Methods Mol Biol. 2009;472:57-88. [PMID: 19107429 DOI: 10.1007/978-1-60327-492-0_3]

This chapter posits that cancer is a complex and multifactorial process as demonstrated by the expression and production of key endocrine and steroid hormones that intermesh with lifestyle factors (physical activity, body size, and diet) in combination to heighten cancer risk. Excess weight has been associated with increased mortality from all cancers combined and for cancers of several specific sites. The prevalence of obesity has reached epidemic levels in many parts of the world; more than 1 billion adults are overweight with a body mass index (BMI) exceeding 25. Overweight and obesity are clinically defined indicators of a disease process characterized by the accumulation of body fat due to an excess of energy intake (nutritional intake) relative to energy expenditure (physical activity). When energy intake exceeds energy expenditure over a prolonged period of time, the result is a positive energy balance (PEB), which leads to the development of obesity. This physical state is ideal for intervention and can be modulated by changes in energy intake, expenditure, or both. Nutritional intake is a modifiable factor in the energy balance-cancer linkage primarily tested by caloric restriction studies in animals and the effect of energy availability. Restriction of calories by 10 to 40% has been shown to decrease cell proliferation, increasing apoptosis through anti-angiogenic processes. The potent anticancer effect of caloric restriction is clear, but caloric restriction alone is not generally considered to be a feasible strategy for cancer prevention in humans. Identification and development of preventive strategies that "mimic" the anticancer effects of low energy intake are desirable. The independent effect of energy intake on cancer risk has been difficult to estimate because body size and physical activity are strong determinants of total energy expenditure. The mechanisms that account for the inhibitory effects of physical activity on the carcinogenic process are reduction in fat stores, activity related changes in sex-hormone levels, altered immune function, effects in insulin and insulin-like growth factors, reduced free radical generation, and direct effect on the tumor. Epidemiologic evidence posits that the cascade of actions linking overweight and obesity to carcinogenesis are triggered by the endocrine and metabolic system. Perturbations to these systems result in the alterations in the levels of bioavailable growth factors, steroid hormones, and inflammatory markers. Elevated serum concentrations of insulin lead to a state of hyperinsulinemia. This physiological state causes a reduction in insulin-like growth factor-binding proteins and promotes the synthesis and biological activity of insulin-like growth factor (IGF)-I, which regulates cellular growth in response to available energy and nutrients from diet and body reserves. In vitro studies have clearly established that both insulin and IGF-I act as growth factors that promote cell proliferation and inhibit apoptosis. Insulin also affects on the synthesis and biological availability of the male and female sex steroids, including androgens, progesterone, and estrogens. Experimental and clinical evidence also indicates a central role of estrogens and progesterone in regulating cellular differentiation, proliferation, and apoptosis induction. Hyperinsulinemia is also associated with alterations in molecular systems such as endogenous hormones and adipokines that regulate inflammatory responses. Obesity-related dysregulation of adipokines has the ability to contribute to tumorigenesis and tumor invasion via metastatic potential. Given the substantial level of weight gain in industrialized countries in the last two decades, there is great interest in understanding all of the mechanisms by which obesity contributes to the carcinogenic process. Continued focus must be directed to understanding the various relationships between specific nutrients and dietary components and cancer cause and prevention. A reductionist approach is not sufficient for the basic biological mechanisms underlying the effect of diet and physical activity on cancer. The joint association between energy balance and cancer risk are hypothesized to share the same underlying mechanisms, the amplification of chemical mediators that modulate cancer risk depending on the responsiveness to those hormones to the target tissue of interest. Disentangling the connection between obesity, the insulin-IGF axis, endogenous hormones, inflammatory markers, and their molecular interaction is vital.

Energy intake, physical activity, energy balance, and cancer: epidemiologic evidence

Energy intake, physical activity, and obesity are modifiable lifestyle factors. This chapter reviews and summarizes the epidemiologic evidence on the relation of energy intake, physical activity, and obesity to cancer. High energy intake may increase the risk of cancers of colon-rectum, prostate (especially advanced prostate cancer), and breast. However, because physical activity, body size, and metabolic efficiency are highly related to total energy intake and expenditure, it is difficult to assess the independent effect of energy intake on cancer risk. There are sufficient evidences to support a role of physical activity in preventing cancers of the colon and breast, whereas the association is stronger in men than in women for colon cancer and in postmenopausal than in premenopausal women for breast cancer. The evidence also suggests that physical activity likely reduces the risk of cancers of endometrium, lung, and prostate (to a lesser extent). On the other hand, there is little or no evidence that the risk of rectal cancer is related to physical activity, whereas the results have been inconsistent regarding the association between physical activity and the risks of cancers of pancreas, ovary and kidney. Epidemiologic studies provide sufficient evidence that obesity is a risk factor for both cancer incidence and mortality. The evidence supports strong links of obesity with the risk of cancers of the colon, rectum, breast (in postmenopausal women), endometrium, kidney (renal cell), and adenocarcinoma of the esophagus. Epidemiologic evidence also indicates that obesity is probably related to cancers of the pancreas, liver, and gallbladder, and aggressive prostate cancer, while it seems that obesity is not associated with lung cancer. The role of obesity in other cancer risks is unclear.

Physical activity and pancreatic cancer risk: a systematic review

BACKGROUND

Physical activity has been associated with a lower risk for pancreatic cancer in several studies, but the overall epidemiologic evidence is not consistent. We therefore did a systematic review to evaluate the association between physical activity and pancreatic cancer risk.

METHODS

We searched MEDLINE and EMBASE through April 2008 and examined the reference lists of the retrieved articles. We excluded studies that relied on job titles as surrogate measures for physical activity. We used a random-effects model to pool study-specific risk estimates comparing the highest versus the lowest category of physical activity.

RESULTS

Total physical activity (occupational and leisure time) was not significantly associated with risk for pancreatic cancer [4 prospective studies; summary relative risk, 0.76, 95% confidence interval (95% CI), 0.53-1.09]. A decreased risk for pancreatic cancer was observed for occupational physical activity (3 prospective studies; relative risk, 0.75; 95% CI, 0.58-0.96) but not for leisure-time physical activity (14 prospective studies; relative risk, 0.94; 95% CI, 0.83-1.05). No association was found with light physical activity (2 prospective studies; relative risk, 1.01; 95% CI, 0.77-1.34), moderate physical activity (6 prospective studies; relative risk, 0.83; 95% CI, 0.58-1.18), or vigorous physical activity (7 prospective studies; relative risk, 0.94; 95% CI, 0.80-1.12).

CONCLUSIONS

This systematic review does not provide strong evidence for an association between physical activity and risk for pancreatic cancer.

Obesity and cancer. Proc Nutr Soc. 2008;67:128-145. [PMID: 18412987 DOI: 10.1017/s0029665108006976]

The prevalence of obesity, defined as a BMI of > or =30.0 kg/m2, has increased substantially over previous decades to about 20% in industrialized countries, and a further increase is expected in the future. Epidemiological studies have shown that obesity is a risk factor for: post-menopausal breast cancer; cancers of the endometrium, colon and kidney; malignant adenomas of the oesophagus. Obese subjects have an approximately 1.5-3.5-fold increased risk of developing these cancers compared with normal-weight subjects, and it has been estimated that between 15 and 45% of these cancers can be attributed to overweight (BMI 25.0-29.9 kg/m2) and obesity in Europe. More recent studies suggest that obesity may also increase the risk of other types of cancer, including pancreatic, hepatic and gallbladder cancer. The underlying mechanisms for the increased cancer risk as a result of obesity are unclear and may vary by cancer site and also depend on the distribution of body fat. Thus, abdominal obesity as defined by waist circumference or waist:hip ratio has been shown to be more strongly related to certain cancer types than obesity as defined by BMI. Possible mechanisms that relate obesity to cancer risk include insulin resistance and resultant chronic hyperinsulinaemia, increased production of insulin-like growth factors or increased bioavailability of steroid hormones. Recent research also suggests that adipose tissue-derived hormones and cytokines (adipokines), such as leptin, adiponectin and inflammatory markers, may reflect mechanisms linked to tumourigenesis.

Pancreatic cancer: a review of the evidence on causation

Pancreatic cancer kills more than 250,000 people each year worldwide and has a poor prognosis. The aim of this article is to critically review the epidemiologic evidence for exposures that may either increase or decrease the risk. A Medline search was performed for epidemiologic studies and reviews published up to April 2007. Consistent evidence of a positive association was found for family history and cigarette smoking. Many studies documented a positive association with diabetes mellitus and chronic pancreatitis, although the etiologic mechanisms are unclear. Other associations were detected, but the results were either inconsistent or from few studies. These included positive associations with red meat, sugar, fat, body mass index, gallstones, and Helicobacter pylori, and protective effects of increasing parity, dietary folate, aspirin, and statins. There was no evidence linking alcohol or coffee consumption with an increased risk of pancreatic cancer. The associations with many exposures need to be clarified from further epidemiologic work in which there is both precise measurement of risk factors, adjustment for potential confounders, and, for dietary studies, information recorded on the method of food preparation and pattern of consumption. Such work is important to reduce the incidence of this fatal disease.

A prospective study of physical activity and the risk of pancreatic cancer among women (United States)

Background

Several epidemiologic studies have examined the association between physical activity and pancreatic cancer risk; however, the results of these studies are not consistent.

Methods

This study examined the associations of total, moderate, and vigorous physical activity to pancreatic cancer in a cohort of 33,530 U.S. women enrolled in the Breast Cancer Detection Demonstration Project (BCDDP). At baseline (1987–1989), information on physical activity over the past year was obtained using a self-administered questionnaire. Cox proportional hazards regression was used to estimate relative risks (RR) and 95% confidence intervals of pancreatic cancer risk.

Results

70 incident cases of pancreatic cancer were ascertained during 284,639 person years of follow-up between 1987–1989 and 1995–1998. After adjustment for age, body mass index, smoking status, history of diabetes, and height, increased physical activity was related to a suggestively decreased risk of pancreatic cancer. The RRs for increasing quartiles of total physical activity were 1.0, 0.80, 0.66, 0.52 (95% CI = 0.26, 1.05; p_trend = 0.05). This association was consistent across subgroups defined by body mass index and smoking status. We also observed statistically non-significant reductions in pancreatic cancer risk for women in the highest quartile of moderate (RR = 0.57; 95% CI = 0.26, 1.26) and highest quartile of vigorous physical activity (RR = 0.63; 95% CI = 0.31, 1.28) compared to their least active counterparts.

Conclusion

Our study provides evidence for a role of physical activity in protecting against pancreatic cancer.

The role of obesity and related metabolic disturbances in cancers of the colon, prostate, and pancreas

Recent evidence indicates that obesity and related metabolic abnormalities are associated with increased incidence or mortality for a number of cancers, including those of the colon, prostate, and pancreas. Obesity, physical inactivity, visceral adiposity, hyperglycemia, and hyperinsulinemia are relatively consistent risk factors for colon cancer and adenoma. Also, patients with type 2 diabetes mellitus have a higher risk of colon cancer. For prostate cancer, the relationship to obesity appears more complex. Obesity seems to contribute to a greater risk of aggressive or fatal prostate cancer but perhaps to a lower risk of nonaggressive prostate cancer. Furthermore, men with type 2 diabetes mellitus are at lower risk of developing prostate cancer. Long-standing type 2 diabetes increases the risk of pancreatic cancer by approximately 50%. Furthermore, over the past 6 years, a large number of cohort studies have reported positive associations between obesity and pancreatic cancer. Together with data from prediagnostic blood specimens showing positive associations between glucose levels and pancreatic cancer up to 25 years later, sufficient evidence now supports a strong role for diabetes and obesity in pancreatic cancer etiology. The mechanisms for these associations, however, remain speculative and deserve further study. Hyperinsulinemia may be important, but the role of oxidative stress initiated by hyperglycemia also deserves further attention.

Body mass index and pancreatic cancer risk: A meta-analysis of prospective studies

A number of studies have examined the association between body mass index (BMI) and risk of pancreatic cancer, but uncertainty about the relationship remains. We performed a meta-analysis to summarize the evidence from prospective studies investigating this association. We searched MEDLINE for studies published in any language from 1966 to November 2006. Prospective studies were included if they reported relative risks (RRs) with 95% confidence intervals (CIs) for the association between BMI and pancreatic cancer incidence or mortality. Study-specific RR estimates were combined by use of a random-effects model. A total of 21 independent prospective studies, involving 3,495,981 individuals and 8,062 pancreatic cancer cases, met the inclusion criteria. The estimated summary RR of pancreatic cancer per 5 kg/m(2) increase in BMI was 1.12 (95% CI, 1.06-1.17; p-heterogeneity = 0.13) in men and women combined, 1.16 (95% CI, 1.05-1.28; p-heterogeneity = 0.001) in men, and 1.10 (95% CI, 1.02-1.19; p-heterogeneity = 0.12) in women. There was no evidence of publication bias (p = 0.58). Findings from this meta-analysis of prospective studies support a positive association between BMI and risk of pancreatic cancer in men and women.

Body mass index, physical activity and the risk of pancreatic cancer in relation to smoking status and history of diabetes: a large-scale population-based cohort study in Japan--the JPHC study

OBJECTIVE

The effects of BMI and physical activity on the risk of pancreatic cancer were investigated in a large population-based cohort study in Japan (JPHC study). In particular, we explored how these effects were influenced by smoking status and a history of diabetes.

METHODS

In total, 99,670 participants (47,499 men, and 52,171 women) were followed for an average of 11 years through the end of 2003. Hazard ratios (HR) and their 95% confidence intervals (CI) were estimated by Cox proportional hazards models.

RESULTS

A total of 224 incident cases (128 men, 96 women) of pancreatic cancer were identified. A statistically significant excess risk of pancreatic cancer was associated with current smoking (HR=1.8, CI 1.1-3.0) and a history of diabetes (HR=2.1, CI 1.3-3.5) among men. A similar increase in risk associated with current smoking (HR=2.0, CI 0.9-4.4) and diabetes (HR=1.5, CI 0.7-3.5) was also seen among women. BMI was inversely associated with risk of pancreatic cancer among men, especially among current male smokers or diabetes patients, but no association was found among women. Leisure-time physical activity was not associated with risk in either men or women.

CONCLUSIONS

Our study confirms the association between cigarette smoking, history of diabetes and increased risk of pancreatic cancer. However, our data suggest that the association between BMI and risk of pancreatic cancer in this Japanese population may be different from that in Western populations.

Body mass index and physical activity as risk factors for pancreatic cancer: the Multiethnic Cohort Study

OBJECTIVE

To examine body mass index (BMI) and physical activity as risk factors for pancreatic cancer.

METHODS

Eight-year prospective data from 77,255 men and 90,175 women including 237 and 235 pancreatic cancer cases, respectively, in the Hawaii-Los Angeles Multiethnic Cohort Study were analyzed. Participants completed a questionnaire that included questions on body weight, height, and physical activity. Cox proportional hazards models were calculated to estimate relative risks (RR) of pancreatic cancer by levels of BMI and total physical activity (as metabolic equivalents (METs)) adjusted for several potential confounders.

RESULTS

Obesity (BMI > or = 30 kg/m(2)) was associated with an increased pancreatic cancer risk in men (RR = 1.51 (95% CI: 1.02-2.26)), but a reduced risk in women (RR = 0.65 (95% CI: 0.43-0.99)). In men the risk was higher in never smokers than in current or former smokers, though differences were not statistically significant. Physical activity was not associated with pancreatic cancer risk in either men or women.

CONCLUSION

The findings suggest, that a BMI of > or = 30 kg/m(2) may be a risk factor for pancreatic cancer in men. No evidence of an effect of physical activity on risk was found.

Obesity, physical activity and the risk of pancreatic cancer in a large Japanese cohort

It is unclear whether body mass index (BMI) and physical activity are associated with the risk of pancreatic cancer in Asian populations. We examined these associations in the Japanese Collaborative Cohort Study for Evaluation of Cancer Risk. Our cohort study included 110,792 Japanese men and women at enrollment (1988-1990). Data on height, body weight (at baseline and at age 20 years) and physical activity were obtained from a questionnaire. Cox proportional hazards models were used to estimate the relative risks of pancreatic cancer mortality. We observed a total of 402 pancreatic cancer deaths during the follow-up period. Men with a BMI of 30 or more at age 20 years had a 3.5-fold greater risk compared with men with a normal BMI. Women with a BMI of 27.5-29.9 at baseline had approximately 60% increased risk compared with women with a BMI of 20.0-22.4. In men, weight loss of 5 kg or more between 20 years of age and baseline age was associated with an increased risk of pancreatic cancer death. In contrast, women with weight loss of 5 kg or more over the same period had a decreased risk. Physical activity was not associated with pancreatic cancer risk in either men or women. Obesity in young adulthood may be associated with an increased risk of death from pancreatic cancer in Japanese men. The risk of pancreatic cancer in relation to BMI seems to differ according to sex and the period over which BMI was measured.

Relation of body mass index to cancer risk in 362,552 Swedish men

BACKGROUND

Obesity has been linked with increased risk for cancers of the colon, kidney, breast, endometrium and gallbladder. For other cancer sites, the relationship with obesity is less well quantified, and the effect of weight change on cancer risk is unclear.

METHODS

We examined the health records of 362,552 Swedish men who underwent at least one physical examination from 1971 to 1992, and were followed until death or the end of 1999. Incident cancer cases were identified by linkage to the Swedish cancer registry. Poisson regression models were used to estimate relative risks of cancer for both body-mass index (BMI) at baseline exam and, in a subgroup of 107,815 men, change in BMI after six years of follow-up, adjusting for age and smoking status.

RESULTS

Compared to men of normal weight, obese men had a significantly increased risk of all cancers combined (RR = 1.1; 95% CI = 1.0-1.2). The risks were most pronounced for esophageal adenocarcinoma (RR = 2.7; 95% CI = 1.3-5.6), renal cell carcinoma (RR = 1.8; 95% CI = 1.4-2.4), malignant melanoma (RR = 1.4; 95% CI = 1.1-1.7), and cancers of the colon (RR = 1.7; 95% CI = 1.5-2.0), rectum (RR = 1.4; 95% CI = 1.1-1.7), and liver (RR = 3.6; 95% CI = 2.6-5.0). Risk of esophageal squamous cell carcinoma was elevated for underweight men whose BMI was less than 18.5 (RR = 3.1; 95% CI = 1.1-8.3). An excess risk for cancers of the pancreas and connective tissue was observed only among nonsmokers. Compared to men whose weight remained stable, men with more than a 15% increase in BMI after six years of follow-up had an elevated risk of pancreas and renal cell cancers.

CONCLUSIONS

Obesity and weight gain increase the risk for several forms of cancer in men, and underscore the need for further study into carcinogenic mechanisms and preventive interventions.

Leptin and cancer

The prevalence of obesity has markedly increased over the past two decades, especially in the industrialized countries. While the impact of excess body weight on the development of cardiac disease and diabetes has been well documented, the link between obesity and carcinogenesis is just being recognized. This review will focus on the link between leptin, a cytokine that is elevated in obese individuals, and cancer development. First, we briefly discuss the biological functions of leptin and its signaling pathways. Then, we summarize the effects of leptin on different cancer types in experimental cellular and animal models. Next, we analyze epidemiological data on the relationship between obesity and the presence of cancer or cancer risk in patients. Finally, leptin as a target for cancer treatment and prevention will be discussed.

Anthropometry, physical activity, and the risk of pancreatic cancer in the European prospective investigation into cancer and nutrition

Tobacco smoking is the only established risk factor for pancreatic cancer. Results from several epidemiologic studies have suggested that increased body mass index and/or lack of physical activity may be associated with an increased risk of this disease. We examined the relationship between anthropometry and physical activity recorded at baseline and the risk of pancreatic cancer in the European Prospective Investigation into Cancer and Nutrition (n = 438,405 males and females age 19-84 years and followed for a total of 2,826,070 person-years). Relative risks (RR) were calculated using Cox proportional hazards models stratified by age, sex, and country and adjusted for smoking and self-reported diabetes and, where appropriate, height. In total, there were 324 incident cases of pancreatic cancer diagnosed in the cohort over an average of 6 years of follow-up. There was evidence that the RR of pancreatic cancer was associated with increased height [RR, 1.74; 95% confidence interval (95% CI), 1.20-2.52] for highest quartile compared with lowest quartile (P(trend) = 0.001). However, this trend was primarily due to a low risk in the lowest quartile, as when this group was excluded, the trend was no longer statistically significant (P = 0.27). A larger waist-to-hip ratio and waist circumference were both associated with an increased risk of developing the disease (RR per 0.1, 1.24; 95% CI, 1.04-1.48; P(trend) = 0.02 and RR per 10 cm, 1.13; 95% CI, 1.01-1.26; P(trend) = 0.03, respectively). There was a nonsignificant increased risk of pancreatic cancer with increasing body mass index (RR, 1.09; 95% CI, 0.95-1.24 per 5 kg/m(2)), and a nonsignificant decreased risk with total physical activity (RR, 0.82; 95% CI, 0.50-1.35 for most active versus inactive). Future studies should consider including measurements of waist and hip circumference, to further investigate the relationship between central adiposity and the risk of pancreatic cancer.

Total cholesterol and body mass index in relation to 40-year cancer mortality (the Corfu cohort of the seven countries study)

PURPOSE

We evaluated risk factors of cancer mortality based on a 40-year follow-up of the Corfu cohort (Seven Countries Study).

MATERIAL AND METHODS

The population studied in this analysis consisted of 529 rural men (49 +/- 6 years old) enrolled in 1961. Since then, periodic visits every 5 years were made to define the causes of death of the participants. Cox proportional hazards models evaluated various risk factors in relation to cancer mortality.

RESULTS

The death rate at the end of the follow-up was 87.1% (i.e., 461 deaths in 529 participants). Of those deaths, 118 (25.6%) were because of cancer (30 deaths were due to cancer of trachea, bronchus, and lung, and the rest were due to other malignant neoplasms). Cancer was the second cause of death in this cohort, after coronary heart disease. Age (hazard ratio, 1.05 per year; P < 0.05), smoking (hazard ratio, 1.97; P < 0.01), total serum cholesterol levels (hazard ratio, 0.95 per 10 mg/dL; P < 0.05), and body mass index (hazard ratio, 0.93 per 1 kg/m2; P < 0.05) showed a significant association with cancer deaths after controlling for physical activity status and anthropometric indices. It should be noted that the protective effect of total cholesterol on cancer mortality was observed only between 183 and 218 mg/dL baseline levels.

CONCLUSION

Cancer was one of the leading causes of death in this cohort. Smoking was associated with increased risk of cancer, whereas moderate total serum cholesterol and increased body and mass index seemed to have a protective effect on 40-year cancer mortality.

Obesity and the risk of pancreatic cancer: an italian multicenter study

OBJECTIVE

The purpose of this work was to determine whether obesity is a risk factor for pancreatic cancer.

METHODS

We studied 400 patients with this tumor and 400 controls matched for sex and age from various Italian cities. We used a standardized questionnaire that was compiled at personal interview, with particular attention to body weight at the time of the interview, and for those with the tumor, their weight before onset of the disease. Body mass index (BMI) was calculated as the patient's weight in kilograms divided by their height in meters squared.

RESULTS

The risk of pancreatic cancer adjusted for smoking was 5-fold higher (P < 0.001) in patients with a BMI less than 23 kg/m2 after diagnosis compared with patients with a BMI ranging from 23 to 29.9 kg/m2, whereas the risk in patients with BMI of at least 30 kg/m2 was not significant (P = 0.689). Taking into account BMI before diagnosis, smoking was confirmed as a significant risk factor (odds ratio = 1.68; P = 0.001) for pancreatic cancer, whereas no significant relationship was found between BMI classes and the risk of pancreatic cancer (P = 0.984).

CONCLUSIONS

These findings indicate that obesity is not a risk factor for pancreatic cancer.

The association of body mass index and pancreatic cancer in residents of southeastern Michigan, 1996-1999

Increased body mass index has emerged as a potential risk factor for pancreatic cancer. The authors examined whether the association between body mass index and pancreatic cancer was modified by gender, smoking, and diabetes in residents of southeastern Michigan, 1996-1999. A total of 231 patients with newly diagnosed adenocarcinoma of the exocrine pancreas were compared with 388 general population controls. In-person interviews were conducted to ascertain information on demographic and lifestyle factors. Unconditional logistic regression models estimated the association between body mass index and pancreatic cancer. Males' risk for pancreatic cancer significantly increased with increasing body mass index (p(trend) = 0.048), while no relation was found for women (p(trend) = 0.37). Among nonsmokers, those in the highest category of body mass index were 3.3 times (95% confidence interval: 1.2, 9.2) more likely to have pancreatic cancer compared with those with low body mass index. In contrast, no relation was found for smokers (p(trend) = 0.94). While body mass index was not associated with pancreatic cancer risk among insulin users (p(trend) = 0.11), a significant increase in risk was seen in non-insulin users (p(trend) = 0.039). This well-designed, population-based study offered further evidence that increased body mass index is related to pancreatic cancer risk, especially for men and nonsmokers. In addition, body mass index may play a role in the etiology of pancreatic cancer even in the absence of diabetes.

Obesity, recreational physical activity, and risk of pancreatic cancer in a large U.S. Cohort

BACKGROUND

Obesity and physical activity, in part through their effects on insulin sensitivity, may be modifiable risk factors for pancreatic cancer.

METHODS

The authors analyzed data from the American Cancer Society Cancer Prevention Study II Nutrition Cohort to examine the association between measures of adiposity, recreational physical activity, and pancreatic cancer risk. Information on current weight and weight at age 18, location of weight gain, and recreational physical activity were obtained at baseline in 1992 via a self-administered questionnaire for 145,627 men and women who were cancer-free at enrollment. During the 7 years of follow-up, 242 incident pancreatic cancer cases were identified among these participants. Cox proportional hazards modeling was used to compute hazard rate ratios (RR) and to adjust for potential confounding factors including personal history of diabetes and smoking.

RESULTS

We observed an increased risk of pancreatic cancer among obese [body mass index (BMI) >/= 30] men and women compared with men and women of normal BMI [<25; RR, 2.08; 95% confidence interval (95% CI), 1.48-2.93, P(trend) = 0.0001]. After adjustment for between BMI, risk of pancreatic cancer was independently increased among men and women who reported a tendency for central weight gain compared with men and women reporting a tendency for peripheral weight gain (RR, 1.45; 95% CI, 1.02-2.07). We observed no difference in pancreatic cancer incidence rates between men and women who were most active (>31.5 metabolic equivalent hours per week) at baseline compared with men and women who reported no recreational physical activity (RR, 1.20; 95% CI, 0.63-2.27).

CONCLUSION

This study, along with several recent studies, supports the hypothesis that obesity and central adiposity are associated with pancreatic cancer risk.

Physical activity and cancer prevention--data from epidemiologic studies

PURPOSE

The aim of this paper is to examine whether physical activity plays any role in the prevention of cancer.

METHODS

To accomplish this, data from published epidemiologic studies on the relation between physical activity and the risk of developing cancer were reviewed.

RESULTS

The data are clear in showing that physically active men and women have about a 30-40% reduction in the risk of developing colon cancer, compared with inactive persons. Although the data are sparse, it appears that 30-60 min.d(-1) of moderate- to vigorous-intensity physical activity is needed to decrease risk. There is a dose-response relation, with risk declining further at higher levels of physical activity. It is also clear that physical activity is not associated with the risk of developing rectal cancer. With regard to breast cancer, there is reasonably clear evidence that physically active women have about a 20-30% reduction in risk, compared with inactive women. It also appears that 30-60 min.d(-1) of moderate- to vigorous-intensity physical activity is needed to decrease the risk of breast cancer, and that there is likely a dose-response relation. For prostate cancer, the data are inconsistent regarding whether physical activity plays any role in the prevention of this cancer. There are relatively few studies on physical activity and lung cancer prevention. The available data suggest that physically active individuals have a lower risk of lung cancer; however, it is difficult to completely account for cigarette smoking. There is little information on the role of physical activity in preventing other cancers.

CONCLUSION

Physical activity is associated with lower risk of developing certain site-specific cancers, in particular colon and breast cancers.

Regional variations in mortality rates of pancreatic cancer in China: Results from 1990-1992 national mortality survey

AIM: To examine the regional variations in mortality rates of pancreatic cancer in China.

METHODS: Aggregated mortality data of pancreatic cancer were extracted from the 1990-1992 national death of all causes and its mortality survey in China. Age specific and standardized mortality rates were calculated at both national and provincial levels with selected characteristics including sex and residence status.

RESULTS: Mortality of pancreatic cancer ranked the ninth and accounted for 1.38% of the total malignancy deaths. The crude and age standardized mortality rates of pancreatic cancer in China in the period of 1990-1992 were 1.48/100000 and 1.30/100000, respectively. Substantial regional variations in mortality rates across China were observed with adjusted mortality rates ranging from 0.43/100000 to 3.70/100000 with an extremal value of 8.7. Urban residents had significant higher pancreatic mortality than rural residents.

CONCLUSION: The findings of this study show different mortality rates of this disease and highlight the importance of further investigation on factors, which might contribute to the observed epidemiological patterns.

A meta-analysis of obesity and the risk of pancreatic cancer

Smoking and diabetes are the only established risk factors for pancreatic cancer. Findings from recent studies suggest that obesity may also be associated with an increased risk of pancreatic cancer, but several earlier studies were less conclusive. We examined this relationship in a meta-analysis of published data. Six case-control and eight cohort studies involving 6391 cases of pancreatic cancer were identified from a computer-based literature search from 1966 to 2003. The relative risk per unit increase in body mass index was estimated for each of the studies from the published data. In a random effects model, the summary relative risk per unit increase in body mass index was 1.02 (95% CI: 1.01-1.03). There was some evidence of heterogeneity between the studies' results (P=0.1). The summary relative risk estimates were slightly higher for studies that had adjusted for smoking and for case-control studies that had not used proxy respondents. The estimated per unit increase in body mass index would translate into a relative risk of 1.19 (95% CI: 1.10-1.29) for obese people (30 kg m(-2)) compared to people with a normal body weight (22 kg m(-2)). These results provide evidence that the risk of pancreatic cancer may be weakly associated with obesity. However, the small magnitude of the summary risk means the possibility of confounding cannot be excluded.