Prostate cancer risk and prevention

By Dr. Ananya Mandal, MDJun 22 2011

Smoking raises risk of death from prostate cancer

According to U.S. researchers smoking increases the risk that men who develop prostate cancer will die from their disease. The longer the men smoked, the greater the risk, said Stacey Kenfield of the Harvard School of Public Health in Boston, whose study appears in the Journal of the American Medical Association. Prostate cancer is the second-leading cause of cancer death in men behind lung cancer

Dr Kenfield and colleagues studied 5,366 men diagnosed with prostate cancer between 1986 and 2006. “We compared current smokers to never smokers. Compared to never smokers, current smokers had a 61 per cent increased risk of dying of prostate cancer, as well as a 61 per cent increased risk of having their cancer return,” Dr Kenfield said.

The researchers added that men who quit smoking at least a decade before they developed cancer appeared to be able to avoid that increased risk.

Prostate cancer vaccine

A new approach to developing cancer vaccines has been used to treat prostate tumors, an international team of scientists has said. For the study they took DNA from healthy cells to create a vaccine, Nature Medicine reports.

The researchers believe the principle could be applied to other cancers and have begun studies on melanoma. Cancer Research UK said it was a significant development, but human trials would be needed. Cancer vaccines are not new. Unlike traditional vaccines which protect against infection, these work by making the immune system attack tumors already in the body. Specifically they target markers on the surface of cancerous cells, known as antigens.

Professor Alan Melcher, of the University of Leeds, explained, “The biggest challenge in immunology is developing antigens that can target the tumor without causing harm elsewhere.” Researchers in Leeds and at the Mayo Clinic, in the US, broke up bits of DNA from healthy prostate cells and inserted them into a virus. The mice were then repeatedly infected with the virus.

The prostate DNA made the virus produce a wide range of prostate antigens, so when the immune system battled the virus it learned to attack the cancerous prostate cells. Crucially, healthy prostate cells and other parts of the body were not affected. In the lab, a course of nine injections with the virus cured 80% of mice with prostate tumors.

Professor Melcher said human trials were years rather than months away. “We have reason to be quite excited. It's not out-of-the-blue research, but based on immunotherapy and virus treatment which are looking very promising and that is what is really exciting,” he added

Professor Peter Johnson, Cancer Research UK's chief clinician, said, “This is an interesting and significant study which could really broaden out the field of immunotherapy research. Although the vaccine didn't trigger the immune system to overreact and cause serious side effects in mice, it will need to be further developed and tested in humans before we can tell whether this technique could one day be used to treat cancer patients.”

Dr Kate Holmes, research manager at the Prostate Cancer Charity, said the study provided “new hope”. “Although we are hopeful that the results of this study could help to form the basis of a new cancer vaccine in future, it is important to remember that the researchers have only investigated the potential of their vaccine in mice. Further research looking at its effect in men is needed. We look forward to the outcome,” she said.