Exercise protects against almost all types of cancer – including prostate cancer. And if you already have prostate cancer, physical exercise in mega doses can triple your chances of survival. In 2004 physiologists at the University of California in Los Angeles published the results of a study which explains how the protective effect of exercise works. In this study, prostate cancer cells in the blood of physically active people self-destructed.
The researchers made grateful use of 12 male participants in the Adult Fitness Program of the University of Nevada Las Vegas for their study. The men had an average age of 60 and all had been taking daily physical exercise for at least 10 years. That meant that they did intensive exercise for an hour five times a week: swimming laps in a pool or doing calisthenics.
The researchers took blood samples from their test subjects, and also from 10 other men who formed a non-active control group. They then added androgen sensitive LNCaP prostate cancer cells to the blood samples. They also did the same test using LN-56 prostate cancer cells. These occur when scientists deactivate the tumour repression gene p53 in LNCaP cells. This gene becomes active when a cell mutates into a cancer cell. The p53 gene helps the cell repair its DNA, stops the cell's growth and, when necessary, induces the cell to deactivate itself.
In the first figure below you can see that the LNCaP cells grew 33 percent less fast in the blood of the active men. The second figure shows that the cancer cells self-destructed 371 percent more often. When the researchers looked at the LNCaP cells, they noticed that the blood of the active subjects doubled the activity of the p53 gene.
The blood of the active men contained less IGF-1. Active muscles absorb IGF-1 from the blood. The researchers suspect that the low IGF-1 level is what deactivated the p53 gene. Of course, it's possible that other factors in the blood play a role too.
"These results provide a mechanism explaining the epidemiological data reporting a reduction in prostate cancer risk in men who are physically active", the researchers conclude.
J Appl Physiol. 2004 Feb;96(2):450-4.