Statin Use Linked to 51% Reduction in Breast Cancer

May 20, 2005

May 20, 2005 (Orlando) — An observational study has found that statin use in U.S. female veterans compared with nonusers was associated with a 51% reduced risk of breast cancer, researchers reported here at the annual meeting of the American Society of Clinical Oncology 2005 Annual Meeting.

The beneficial effect is seen in more than four years of statin use, said lead author Ruby Kochhar, MD, who led the study at the Overton Brooks VA Medical Center at Shreveport, Louisiana.

The retrospective case-control study compared statin use among 556 women with a history of breast cancer and 39,865 women without the disease who served as controls. Breast cancer was identified by International Classification of Diseases codes, and statin use was tracked by prescription.

The patients were selected from a database of 1.4 million patients involving 10 Veterans Affairs centers in Louisiana, Texas, Arkansas, and Mississippi from 1998 to 2004.

Researchers controlled for age, smoking, alcohol use, and diabetes, all of which were associated with an increased risk of cancer in this group of patients, said Dr. Kochhar, now at the Portsmouth Naval Medical Center, Portsmouth, Virginia.

Dr. Kochhar noted that, although this was a large observational case-control study, it had the following limitations: it lacked compliance information, and it did not account for factors that are known to increase the risk of breast cancer, such as family history, hormone replacement therapy, and benign breast disease. However, the odds ratio was 0.49, which was statistically significant (P < .0001).

Also, Dr. Kochhar said that researchers need further analysis of the dataset to determine any associations with the type of statins or the total dosage of statins that affect breast cancer risk.

The breast cancer study was one of many presented here at ASCO that involved use of statins for chemoprevention of cancer. Several of the other studies were also observational studies, reporting an association of statin use with an approximate 50% risk reduction for lung, prostate, and colorectal cancers.

In a separate session at ASCO, Scott M. Lippman, MD, professor and chair of clinical cancer prevention, M.D. Anderson Cancer Center, commented on the group of statin studies noting, "Interest in statins in cancer prevention originally was a fairly unusual route. They are now considered one of the most promising classes of cancer prevention."

Earlier, there had been concern that statins might actually increase risk of cancer, Dr. Lippman said. However, researchers did not find any increase in cancer incidence after they analyzed several large randomized studies using statins for cardiovascular disease. In some cases, cancer incidence was found to be reduced, Dr. Lippman said.

Although a press conference was held here at ASCO on the breast cancer study, Dr. Lippman said he chose to focus on the observational study of statins that showed a protective effect in prostate cancer.

In both the prostate and lung cancer studies, there was a 48% to 54% risk reduction in cancer associated with statin use. Both of the studies were completed using the South Central VA Healthcare Network, which also was used in the breast cancer study. In all of the statin studies, a high degree of statistical significance was reached (P < 0.001).

However, Dr. Lippman said the prostate cancer study was the most convincing because it had more supporting evidence compared with the other observational studies.

Dr. Lippman noted that the preliminary results on the duration of statin use in the prostate cancer study yielded an odds ratio of close to 1 for those who used statins for more than four years. "That is a 90% reduction in prostate cancer risk." Dr. Lippman said.

ASCO 2005 Annual Meeting: Abstracts 514, 1004, 3530. Presented May 15, 2005.

Reviewed by Gary D. Vogin, MD

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