Prostate cancer patients who receive high-dose radiotherapy and also take cholesterol-lowering statins are more likely to be free of the malignancy five and 10 years later than patients on radiotherapy alone, according to new research presented at the American Society for Therapeutic Radiology and Oncology’s Annual Meeting in Los Angeles yesterday (31 October).
US researchers retrospectively studied 871 men with prostate adenocarcinoma treated between January 1995 and July 2000 with high-dose radiotherapy. Nineteen per cent were taking statins when they were diagnosed with prostate cancer. None of the patients stopped using statins during radiotherapy. The authors defined a relapse as a predefined rise in levels of prostate specific antigen (PSA). The median follow-up lasted 85 months.
After five and 10 years, 91% and 76% respectively of the men taking a statin had not relapsed. This compared with 81% and 66% respectively for men not using statins. There was also a trend toward lower incidence of distant metastases among men taking a statin, although this did not reach statistical significance. The effect of statins was most marked in patients with aggressive or advanced prostate cancer. Overall, they seemed to increase the likelihood of relapse-free survival by almost 60% (hazard ratio 1.58).
“We were, indeed, surprised by the findings that statins used by these patients for other conditions were shown to improve the effectiveness of radiation treatment in killing prostate cancer cells,” said Michael Zelefsky, senior author of the study and a radiation oncologist at the Memorial Sloan-Kettering Cancer Center in New York.
“We speculate that statins appear to sensitise the cancer cells to the radiation therapy," he commented. "Some researchers have postulated that statins could lead to reduced activation of onco-proteins [proteins linked to cancer] and expression of the cancer. So statins may not affect the initiation of cancer, but possibly reduce the progression of an existing cancer.”
Further studies needed
Zelefsky added that using statins during radiation may also help with the treatment of other types of cancer. “However, more studies are necessary to explore the association between statins and radiation treatment in curing cancers,” he concluded.