Low levels of an obesity-related hormone (lipocalin) are associated with an increased risk of pancreatic cancer, researchers report. In a case-control trial study, Dr. Ying Bao (MD, ScD) and his colleagues at Harvard University in Boston found that patients with pancreatic cancer had significantly lower levels of the hormone in blood samples compared to the period one year or more prior to their diagnosis. The association was independent of factors such as smoking, diabetes, body mass index and other known or uncertain risks of pancreatic cancer. They conclude that the findings provide additional evidence of a biological link between obesity, insulin resistance and pancreatic cancer risk; they also suggest that lipocalin has an independent role. The researchers noted that pancreatic cancer is one of the top four leading cancers for cancer deaths in the United States, but its etiology is not well understood. However, there is growing evidence that obesity is an important risk factor for pancreatic cancer, suggesting that lipocalin, which is secreted by adipose tissue, may also play an important role. To confirm the relationship between lipocalin and pancreatic cancer, they conducted five large, long-term prospective cohort studies: the Health Professionals Follow-up Study, the Nurses’ Health Study, the Physicians’ Health Study, the Women’s Health Initiative, and the Women’s Health Study. Of the nearly 360,000 participants, they selected 468 pancreatic cancer patients who had blood samples from more than 1 year prior to diagnosis and did not have any other cancers other than non-melanoma. The researchers randomly selected another 1,080 patients as a control cohort, which was matched to the same cohort on factors such as age, smoking and fasting status, and month of blood collection. Analysis of the results showed that the median blood lipocalin in pancreatic cancer patients was 6.2 mcg/ml compared to 6.8 mcg/ml in the control group, with a significant difference between the two groups, P=0.009. There was also an inverse association between blood lipocalin and cancer risk, which persisted across the five prospective cohorts and was an independent marker of insulin resistance such as diabetes. When lipocalin levels were divided into 5 classes, high levels of lipocalin were associated with a low risk of cancer. This was especially true when compared to the lowest levels: Participants in the second tier had a cancer ratio of 0.61 with a 95% confidence interval of 0.43 to 0.86. Participants in the third tier had a cancer ratio of 0.58 with a 95% confidence interval of 0.41 to 0.84. Participants in the fourth tier had a cancer ratio of 0.59 with a 95% confidence interval of 0.40 to 0.87. Dr. Jianliang Zhang (PhD) and Dr. Steven Hochwald (MD) of Roswell Park Cancer Institute in Buffalo, New York, commented that the study was done carefully, but the exact role of lipocalin is still not clear. The exact role of lipocalin is still not well understood. In a subsequent editorial, they agreed that the study confirmed a link between lipocalin and pancreatic cancer risk, but added that it is still important to determine the exact interaction between the hormone and the malignancy. They believe the study opens up the possibility that hormones could be diagnostic markers and therapeutic targets. Zhang and Hochwald said, “Early screening to assess lipocalin has the potential to improve survival in patients with pancreatic tumors.” They said, “It can also be hypothesized that increasing circulating lipocalin with therapeutic interventions could potentially halt the progression of pancreatic cancer and/or improve the survival of patients with malignancies.