Virus, cancer & Nobel Prize in Medicine

The Nobel Assembly in Stockholm has just announced the winners of the 2008 Nobel Prize in Medicine. The winners are Harald zur Hausen of Germany and the French researchers Francoise Barre-Sinoussi and Luc Montagnier. Zur Hausen was cited for finding human papilloma viruses that cause cervical cancer, the second most common cancer among women. Barre-Sinoussi of the Institut Pasteur in Paris and Montagnier, Director of the World Foundation for AIDS Research and Prevention, were cited for their discovery of human immunodeficiency virus (HIV) which causes AIDS. Kaposi sarcoma is common in AIDS patients.

There are many viruses which lead to the development of cancers in humans. At present, pancreatic cancer has not been linked to a specific virus. However, a recent publication from the University of Texas M. D. Anderson Cancer Center suggested a possible association between hepatitis B virus (HBV) and pancreatic cancer (J Clin Oncol 2008; 26: 4557 – 4562). The aim of their study was to determine whether HBV and hepatitis C virus (HCV) infections increase the risk for the development of pancreatic cancer. The researchers studied the blood samples from 476 pancreatic cancer patients and 879 age-, sex- and race-matched healthy controls. The samples were tested for the presence of HCV antibodies (anti-HCV), HBV surface antigen (HBsAg), antibodies to HBV core antigen (anti-HBc) and antibodies to HBsAg (anti-HBs). They found that the prevalence of past exposure to HBV, indicated by the presence of anti-HBc, was significantly higher in pancreatic cancer patients (7.6%) than controls (3.2%). Compared to controls, people who had had previous exposure to HBV but had developed immunity are 2.3 times more likely to develop pancreatic cancer. Diabetes also significantly increased the risk of pancreatic cancer in patients with past exposure to HBV. If you are an HBV carrier, you are 4 times more likely to develop pancreatic cancer. Interestingly the researchers did not find a significant association between HCV infection and pancreatic cancer.

The researchers have not proved that HBV causes pancreatic cancer. They have shown an association between HBV infection (past or present) and pancreatic cancer. They have suggested that perhaps because of their (the liver and pancreas) close proximity and sharing of blood supply and ducts, the pancreas may suffer collateral damage from the HBV infection and thus be predisposed to the development of cancer.

With many more years of research, it may be possible that a specific virus might be identified as the causal agent for pancreatic cancer. Until then we can only be vigilant and pay more attention to individuals with associated risk factors for pancreatic cancer. These are:- a history of diabetes mellitus, cigarette smoking, a

positive family history of cancer and possibly past / present history of HBV infection.