Animal Fat Consumption and Pancreatic Cancer Incidence: Evidence of Interaction with Cigarette Smoking

Purpose

A large difference in fat intake and pancreatic cancer incidence exists among populations worldwide. This study investigated the relation between fat consumption and pancreatic cancer risk at the population level.

Methods

Fat consumption data for nine periods (1964–1994) and age-standardized pancreatic cancer incidence data for five periods (1973–1997) in 35 countries were derived from the Food and Agriculture Organization and World Health Organization, respectively.

Results

A significant positive correlation was found between animal fat consumption and pancreatic cancer incidence in all periods examined (r = 0.40–0.74, p = 0.021 to < 0.0001 in men and r = 0.50–0.66, p = 0.01 to 0.0001 in women). After adjustment for smoking and other confounders, animal fat consumption in all nine periods considered was still significantly and positively associated with pancreatic cancer incidence in the 1993 to 1997 period in both sexes. The stratified analysis showed that this association was significant only in countries with below median level of smoking (< 2273 cigarettes/adult/year). A similar but less pronounced effect was observed for total fat consumption.

Conclusions

The consumption of fat, especially animal fat, was associated with an increased risk of pancreatic cancer and this association was modified by levels of cigarette smoking.

Introduction

Pancreatic cancer is one of the leading causes of cancer death in both sexes in the US (1). The American Cancer Society has predicted that 31,860 new cases will be diagnosed and 31,270 will die from the disease in 2004 (1). The International Agency for Research on Cancer (IARC) reported that 216,367 new cases and 213,462 deaths occurred worldwide in 2000 (2). The majority of these tumors are primary adenocarcinomas of the exocrine pancreas (3). Because of the insidious and rapid progressive nature of and a lack of an effective screening method for this malignancy, most patients are diagnosed at an advanced stage, with a median survival time of 6 months or less and a 5-year survival rate of only about 4% 3, 4). Given its incidence and almost uniform case fatality, pancreatic cancer poses a major public health problem in the US and other developed countries.

The etiology of pancreatic cancer is virtually unknown with cigarette smoking as the only established risk factor 5, 6, 7, 8. It has been consistently observed in epidemiological studies that cigarette smokers have an increased risk of pancreatic cancer as compared to non-smokers 9, 10, 11. A multi-center case–control study showed that 26% to 29% of pancreatic cancer is attributable to smoking in the US (9). Large differences in incidence rates of pancreatic cancer across populations in different parts of world suggest that environmental, especially nutritional, factors play an important role in the etiology of this dreadful disease (12). The World Cancer Research Fund and the American Institute of Cancer Research have estimated that nutrition accounts for 30% to 50% of pancreatic cancer (13). However, the associations between specific nutrients and pancreatic cancer are poorly understood. Incidence rates of pancreatic cancer are generally higher in North America and Europe than in Asia and Africa (14), suggesting that the Western diet may be involved in pancreatic carcinogenesis. A high intake of fat, particularly saturated fat, is a remarkable dietary characteristic of Western populations (15). Fat intake has been associated with an increased risk of breast, prostate, and colorectal cancers in many epidemiological studies 16, 17, 18. To date, however, little is known about the relation between fat intake and pancreatic cancer risk. The primary purposes of this ecological study were to investigate whether fat intake is associated with pancreatic cancer risk and, if so, whether this association is modified by cigarette smoking among 35 populations worldwide.