Pancreatic cancer is a rare disease. Producing few early symptoms, the disease is unfortunately usually diagnosed only once the cancer is advanced. However, even it is found fairly early and removed, only one in five patients survive five years. There is also no effective cure. It is thus no surprise that this malignancy is the fourth leading cause of cancer deaths in the United States.
Because it is fatal so often, there’s been an effort to understand what might predispose someone to develop the disease. Studies to date indicate that cigarette smoking doubles the risk, and a host of other factors also increase the odds that someone will develop the cancer (for example, obesity, chronic pancreatitis, diabetes, cirrhosis, and chewing tobacco). Taken together, however, these risks still only explain about a quarter of cases.
Several epidemiological studies have indicated that certain agricultural chemicals, principally weed killers, might increase the risk. So researchers at the National Cancer Institute’s division of cancer epidemiology and genetics decided to probe risks of the disease among the 89,000 participants of the long-running federally funded Agricultural Health Study. Its participants include 57,000 private, licensed pesticide applicators (mostly white men) and some 32,000 wives of applicators. All lived in Iowa or North Carolina; they were recruited in the mid-1990s.
Throughout the first seven years of follow-up, 93 cases of pancreatic cancer developed — 64 in applicators, the rest in spouses. As in other studies, smoking, having diabetes, or being over-weight increased an individual’s odds of developing cancer. But after adjusting for these risk factors, two of the 50 pesticides reviewed showed a statistically significant correlation with the cancer (pendimethalin [sold under such trade names as Accotab, Go-Go-San, Herbadox, Penoxalin, Prowl, Sipaxol, Stomp and Way-Up] and EPTC [also known as Eptam, Eradicane, Shortstop and Genep]). The cancer risk increased 40% among people who had incurred moderate exposure to pendimethalin or had employed lots of protective gear when applying it. Among mores highly exposed individuals, the pancreatic cancer risk was triple the rate seen among those applicators never exposed to this herbicide. Similarly, there was an 80% increased risk for relatively low-level exposures to EPTC. The risk jumped among the more heavily exposed individuals to two-and-a-half times the cancer risk in pesticide applicators who had never used this chemical.
The researchers acknowledge that the mechanisms by which either chemical might trigger pancreatic cancer remains unknown; they speculate it might have something to do with the fact that the one can harbor the carcinogen nitrosamine as a trace impurity and both weed killers are able to form related N-nitroso compounds. Nitrosamines and related compounds are suspected human carcinogens affecting tissues, including the pancreas.
The study can be found at http://www3.interscience.wiley.com/journal/121538829/abstract?CRETRY=1&SRETRY=0.