Question

Hepatitis B and Pancreatic Cancer.The article "Study Links Hepatitis B and Cancer of Pancreas" by D. Grady, appeared in the September 29, 2008 issue of the New York Times. It reported that, for the first time, a study showed that people with pancreatic cancer are more likely than those without the disease to have been infected with the hepatitis B virus. The study by M. Hassan et al . , titled "Association Between Hepatitis B Virus and Pancreatic Cancer" (Journal of Clinical Oncology, Vol. 26, No. 28, pp. 4557-4562) compared 476 people who had pancreatic cancer with 879 healthy control subjects. All were tested to see whether they had ever been infected with the viruses that cause hepatitis B or hepatitis C. The results were that no connection was found to hepatitis C, but the cancer patients were twice as likely as the healthy subjects to have had hepatitis B. The researchers noted, however, that "...while the study showed an association, it did not prove cause and effect. More work is needed to determine whether the virus really can cause pancreatic cancer." Explain the validity of the statement in quotes.

Short answer

The given study is observational.

Step-by-step solution

Step 1. Given information.

The given statement says that people with pancreatic cancer are more likely to have been infected with the hepatitis B virus.

It is also given that 476 people have pancreatic cancer compared with 879 healthy ones.

Step 2. Explanation.

The study is an observational study because It only demonstrates that those with pancreatic cancer are more likely than people without the disease to have had their first hepatitis B infection.

The study compared 476 pancreatic cancer patients to 879 healthy controls.

It's a controlled trial, and further research is needed to demonstrate causation and determine whether the virus can cause pancreatic cancer.