Lifestyle factors and pancreatic cancer risk: A cohort study from the Swedish Twin Registry

Abstract

Dear Sir,Even though pancreatic cancer is the 5th-leading cause of cancer deaths in the Western world, 1 little is known about the etiology of the disease. Lifestyle and other risk factors for pancreatic cancer have been examined in many epidemiologic studies, most of which were case-control studies. The conclusions of many of these are dubious because of small sample size, low participation and use of proxy respondents. Only cigarette smoking stands out as a likely causal agent in epidemiologic studies. However, cigarette smoking can explain only about 25% of the incidence. 2 Studies have also suggested that coffee, ethanol, obesity, high energy intake and high consumption of fat, carbohydrates and animal protein may be risk factors. [3][4][5] Some studies have shown decreased risks associated with frequent consumption of fruits and vegetables, but this has not been observed consistently. 3 It is possible that factors other than those that have been investigated may affect the development of pancreatic cancer.Our study examined the effects of diet, coffee, ethanol, tobacco use, BMI, physical activity and change in body weight on pancreatic cancer incidence in a cohort study of twins established in 1958 and followed by the Swedish Twin Registry. The cohort, which provided prospective information concerning exposure, included male and female same-sexed twin pairs who were born from 1886 -1925 and were both living in Sweden in 1961. At the 1961 baseline, self-administered questionnaires regarding lifestyle factors were mailed to 25,778 registrees. However, 1,288 of these were found to have already died. Additional questionnaires were administered in 1963 and 1967. Our current study included 12,204 females and 9,680 males who responded to these questionnaires with information on at least some of the potential risk factors. The overall response rate to the questionnaires was 85%.

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

“…In studies carried out in the U.S.A., a positive relationship was demonstrated for both men and women in the 3 largest cohort studies, [15][16][17] while 4 other smaller studies found a positive association only in men. 10,22,26,33 The 6 other studies, including the 2 largest European cohort studies, 6,[18][19][20][21]35 did not find any significant association in the combined data of men and women. Similar to cohort studies, case-control studies have also produced contradictory results with a meta-analysis carried out in 2003 concluding that the risk of pancreatic cancer was only weakly associated with obesity.…”

“…Since 2000, at least 13 prospective cohort studies carried out in Western countries have reported a link between BMI and pancreatic cancer risk, 6,10,[15][16][17][18][19][20][21][22]26,35 although the findings have been inconsistent. In studies carried out in the U.S.A., a positive relationship was demonstrated for both men and women in the 3 largest cohort studies, [15][16][17] while 4 other smaller studies found a positive association only in men.…”

Meat and fat intake and pancreatic cancer risk in the Netherlands Cohort Study

“…3 To date, 11 cohort studies have investigated the relation between the intake of total meat, different meat types and eggs and pancreatic cancer risk. 3,6,[8][9][10][11][12] Two studies have observed a positive association with total meat intake, 3,11 the Multiethnic Cohort Study has observed increased risks with the intake of beef and pork, 3 and a cohort among 7th-day Adventists has observed a positive association with egg intake. 3 Inverse associations were observed with the intake of pork in a study of Swedish twins 8 and with the intake of poultry among Swedish women.…”

“…6,7 Since then, numerous epidemiological studies have investigated the relation between meat, eggs, and different types of fat and pancreatic cancer, including 15 prospective cohort studies 3,6,[8][9][10][11][12] and 31 case-control studies. 3,6,[13][14][15][16][17][18][19] In a recent Expert Panel Report, it was concluded that there is limited evidence suggesting that red meat is a cause of pancreatic cancer in humans.…”

Meat and Meat-Mutagen Intake and Pancreatic Cancer Risk in the NIH-AARP Cohort

“…The association between meat intake and pancreatic cancer has been examined in both case control and cohort (23)(24)(25)(26)(27)(28)(29)(30)(31)(32) studies with positive (2-7, 9-12, 22-27), inverse (13)(14)(15)28), and null (4, 5, 8, 14-21, 29, 32) associations reported for both study designs. The inconsistent results among case-control studies may partly be due to retrospective ascertainment of diet, which, given the rapid fatality of pancreatic cancer, may be fraught with biases, such as recall and proxy, and reverse causation.…”