Mammogram Shown To Be Most Effective 12 Months After Radiotherapy

Breast cancer patients who receive breast-conserving therapy and radiation do not require a follow-up mammogram until 12 months after radiation, despite current guidelines that recommend follow-up mammograms at between 6 and 12 months after radiation.

Many women diagnosed with breast cancer 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 vital part of post-treatment surveillance for patients undergoing breast-conserving therapy, but the optimal timing of the initial mammogram is not clear.

Researchers from the departments of radiation oncology, pathology, and radiology at the University of California, San Diego (UCSD; USA), School of Medicine tried to determine if the recommended timeframe for a post-treatment mammogram offers any benefit to patients and published their findings November 15, 2008, study in the International Journal of Radiation Oncology Biology Physics.

The most recent U.S. National Comprehensive Cancer Network (NCCN) guidelines proposes a follow-up mammogram 6 to 12 months after radiation, and according to 2006 guidelines, the American Society of Clinical Oncology (ASCO) recommends a follow-up mammogram one year after the first mammogram that leads to diagnosis, but no earlier than 6 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 performed six to nine months after the completion of radiation.

The researchers evaluated 408 patients who were treated with breast-conserving therapy and radiation between 1995 and 2005 and who had follow-up mammograms at UCSD within one year after completing radiation. The median interval between radiation and the initial mammogram was 3.1 months. Ten 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 approximately US$115, and many women can experience moderate to severe pain during the procedure and high levels of anxiety during a needle biopsy. The researchers 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 (West Covina, CC, USA), said.

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