Comments on USPSTF Review of Medications to Reduce the Risk for Primary Breast Cancer

Comments on USPSTF Review of Medications to Reduce the Risk for Primary Breast Cancer

Date: May 9, 2013   Key words: breast cancer, chemoprevention, SERMs

The USPSTF recently undertook a review of the topic of chemoprevention of primary breast cancer; that is, the use of pharmaceutical agents (i.e., selective estrogen receptor modulators, SERMs) to lower a high risk woman’s chances for developing the disease.

This analysis does not represent new information. The results of the NSABP P-1 trial (tamoxifen vs. placebo) and the STAR trial (tamoxifen vs. raloxifene) have been well established in the medical literature and clearly demonstrate that these agents are effective in breast cancer risk reduction. However, as the Task Force acknowledges, neither tamoxifen nor raloxifene have come into widespread use for breast cancer risk reduction. The reasons for the lack of uptake of this strategy remain unclear, and the Task Force report provides little guidance for physicians and patients as they consider this topic today.

Research into the prevention of breast cancer is impeded by the limitations of the available risk assessment models which may not be applicable to all ethnic groups and are inaccurate for very young women, those with genetic susceptibility to breast cancer, and women whose risk emanates from conditions such as LCIS. In addition, new information regarding the risks associated with breast density and BMI has not been incorporated into the commonly used risk assessment models. It may be difficult for physicians to counsel individual patients regarding their risks when objective measures of breast cancer risk are so lacking.

The current studies are also insufficient to describe the optimal age to utilize agents for chemoprevention, and women who consider initiating tamoxifen may be rightfully concerned regarding the duration of protection as they age. And particularly for premenopausal women, the interference with fertility may play a role in reducing the uptake of tamoxifen for chemoprevention. It is quite likely that the majority of physicians who provide primary care to women at increased risk are unaware of the validated tools available to accurately estimate a woman’s risk of developing breast cancer (e.g. www.cancer.gov/bcrisktool) or how to estimate the net benefit that would accrue to women who undertook a program of chemoprevention for reducing their risk of breast cancer. The current studies do not define the optimal age to utilize agents for chemoprevention, and women who consider initiating tamoxifen may be rightfully concerned regarding the duration of protection as they age.

Clearly, better agents are needed to maximize the risk reduction benefit and minimize potential side effects. In addition, we need better methods to quantify breast cancer risk, and there is broad interest in the use of cell and tissue-based methods for breast cancer risk assessment that may provide women with a more accurate and individualized understanding of their risk for the disease, and allow us to monitor the effectiveness of risk reducing interventions.