Diabetes Increases Men's Risk of Liver, Pancreatic Cancer, Study Finds

Men who reported they have diabetes and take medication for it are at four times the risk of developing liver cancer compared with men without diabetes, according to study results presented last week at the American Association of Cancer Research (AACR) "Frontiers in Cancer Prevention Research" conference. The case-control study - which involved nearly 3,300 men in Montreal, Canada, newly diagnosed with 1 of 12 types of cancer, and more than 500 healthy controls - also found that men who reported having diabetes and taking medication for it had more than two and a half times the risk of developing pancreatic cancer compared with men who did not have diabetes.

Overall, 24 percent of liver cancer patients, 16 percent of pancreatic cancer patients, and 8 percent of controls reported having diabetes. No association was found between diabetes and melanoma, non-Hodgkin's lymphoma, and stomach, colon, and prostate cancer. Men were asked about medication use for diabetes to minimize misclassification of disease. When only accounting for self-reports of diabetes without medication use, the associations between diabetes and liver and pancreatic cancer were reduced to three times the risk of developing liver cancer and two times the risk of developing pancreatic cancer.

The study confirms earlier findings of a link between diabetes and liver and pancreatic cancers, said study leader Dr. Marie-Claude Rousseau of the University of Montreal. The next steps, she added, are to define the biological mechanisms by which diabetes may cause cancer, "if it's indeed causal," and perhaps focusing on liver and pancreatic cancer, "since these are the [cancers] coming most consistently from the literature."

Height May Be Another Risk Factor for Prostate Cancer

At the AACR prevention research conference last week, researchers from NCI and the Finnish National Public Health Institute presented data showing that, in male smokers, greater adult height is associated with an increased risk of prostate cancer. The data come from more than 29,000 participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which examined the long-term effects of vitamin supplements in Finnish male smokers between 1985 and 1993, and is continuing to follow participants.

The men, aged 50 to 69 years, had their height and weight measured by a specially trained nurse, gave information on demographic, smoking, and medical factors, and completed a detailed food frequency questionnaire at the start of the ATBC study. After 17.4 years, a total of 1,346 cases of prostate cancer were identified. This analysis showed that, compared with the shortest men in the study, the risk for prostate cancer was approximately 20 percent higher among the tallest men. The tallest men also had a two-fold higher risk of advanced disease. "Our results help to clarify previous inconsistencies in the literature, and offer some insights into the etiology of prostate cancer," says Dr. Margaret Wright, one of the lead investigators from NCI's Division of Cancer Epidemiology and Genetics. "The possibility that height may be associated with prostate cancer risk should be studied further to evaluate whether taller men are particularly susceptible to advanced disease, but not early cancer."

Ductal Lavage May Not Detect Breast Cancer

Ductal lavage, a method for collecting cells from breast milk ducts, was thought to have potential as a screening tool for breast cancer after a previous study showed that milk ducts may contain diseased cells. But a study in the October 20 Journal of the National Cancer Institute shows that the method may not be sensitive enough for effective breast cancer screening. The research was sponsored by Cytyc Corporation, the Bluhm Family Program for Breast Cancer Prevention and Early Detection, and NCI.

In this pilot study, researchers performed ductal lavage on 44 breasts from 39 women prior to mastectomy. Thirty-two of the women already had been diagnosed with breast cancer, but seven had not yet been diagnosed and were undergoing mastectomy for prophylactic reasons. Analysis of the cells from ductal lavage showed poor agreement, in terms of cancer detection, when compared with the results of microscopic examination of breast tissue. Cancer cells were detected with the ductal lavage screen in only about half of the cases.

The researchers speculate that this may be because ducts that produced fluid were not proximal to the site of cancer, because ducts that contained cancer failed to yield fluid, or because the cancerous ducts that yielded fluid showed benign or mildly atypical cells. "Although further studies are warranted in women with early lesions," the authors write, "our results and those of others indicate that ductal lavage should not be recommended to high-risk women as a technique to detect cancer earlier than imaging modalities."

Stroke After Breast Cancer Linked to Chemotherapy, But Not to Tamoxifen

In two recent clinical trials, a disproportionate number of strokes occurred among women who received tamoxifen, a nonsteroidal hormone used to treat and prevent breast cancer, raising concerns that the hormone may be to blame. To examine this possibility, researchers from Kaiser Permanente Southern California and the Keck School of Medicine at the University of Southern California conducted a case-control study, funded by NCI, of first stroke after breast cancer. Study results appeared in the October 20 Journal of the National Cancer Institute.

All of the women in the study had been diagnosed with a first invasive breast cancer at Kaiser Permanente Southern California, and had a stroke some time later. The researchers matched medical records of 353 control patients to the records of 179 case patients, and also conducted interviews to determine the women's breast cancer treatment history, medical and reproductive history, and smoking status.

Analysis showed that neither tamoxifen nor radiation therapy was associated with the women's strokes, but that chemotherapy was. They give several possible explanations for the increased risk of stroke, including blood clots resulting from occult malignancies in women with aggressive cancer who are more likely to receive chemotherapy, as well as atherosclerotic disease resulting from the chemotherapeutic agents. "Although this study cannot generate specific recommendations," the authors wrote, "it seems logical that women with a history of chemotherapy may benefit from approaches to reduce stroke risk."