Mammogram most effective 12 months after radiation treatment

November 25, 2008

Breast cancer patients who receive breast-conserving therapy and radiation do not need a follow-up mammogram until 12 months after radiation, despite current American Society of Clinical Oncology (ASCO) and National Comprehensive Cancer Network (NCCN) guidelines that recommend follow-up mammograms at between six and 12 months after radiation, according to a November 15 study in the International Journal of Radiation Oncology*Biology*Physics, the official journal of the American Society for Therapeutic Radiology and Oncology.

According to the American Cancer Society, more than 182,000 women will be diagnosed with breast cancer in 2008, and many of these women will choose to undergo a lumpectomy and radiation therapy as their course of treatment, which has been shown to produce similar survival outcomes to a mastectomy. Mammography has been established as a crucial part of post-treatment surveillance for patients undergoing breast-conserving therapy, but the optimal timing of the initial mammogram is not clear.

Researchers at the University of California, Los Angeles, School of Medicine, Department of Radiation Oncology, Department of Pathology, and Department of Radiology and at the University of California, San Diego, School of Medicine sought to determine if the recommended timeframe for a post-treatment mammogram offers any benefit to patients.

The most recent NCCN guidelines proposes a follow-up mammogram six to 12 months after radiation, and according to 2006 guidelines, ASCO recommends a follow-up mammogram one year after the initial mammogram that leads to diagnosis, but no earlier than six months after radiation. Accounting for the time after the initial diagnostic mammogram to have a biopsy, surgery and radiation therapy, following the ASCO guidelines would likely result in mammograms being done six to nine months after the completion of radiation.

The researchers looked at 408 patients who were treated with breast-conserving therapy and radiation between 1995 and 2005 and who had follow-up mammograms at UCLA within one year after completing radiation. The median interval between radiation and the initial mammogram was 3.1 months. Only 10 patients had suspicious findings on their mammograms and of those only two were found to have recurrent cancer. Both of the cases were noninvasive ductal carcinomas.

The cost of a mammogram is about $115 and many women can experience moderate to severe pain during the procedure and high levels of anxiety during a needle biopsy. The authors determined that because only 0.49 recurrences were detected per 100 mammograms and only noninvasive ductal carcinoma was found, mammograms should not be performed until at least one year after radiation to avoid the medical and psychological costs associated with mammography.

"Omitting the initial post-radiotherapy examination may improve the psychological well-being of patients, especially for women who have already been shown to have breast cancer," Kevin Lin, M.D., lead author of the study and a radiation oncologist at Advanced Oncology Center in West Covina, Calif., said.

Source: American Society for Therapeutic Radiology and Oncology