A breast cancer patient who undergoes brachytherapy has double the chance of losing her breasts compared to one who is treated with whole-breast irradiation, researchers from the MD Anderson Cancer Center, Houston, explained at SABCS (34th Annual San Antonio Breast Cancer Symposium).

Brachytherapy is radiation treatment given by placing radioactive material directly in (or near) the target. Brachytherapy simply means internal radiation therapy. For breast cancer patients, a small radioactive source is placed inside the breast after lumpectomy. Whole breast irradiation is a type of external beam radiation therapy which is aimed at the entire breast, as well as the chest wall and lymph node, if necessary.

Benjamin D. Smith, M.D. and team set out to determine how brachytherapy impacts on outcomes for women with incident-invasive breast cancer. They gathered data on 130,535 females over 66 years of age who had been diagnosed with incident-invasive breast cancer from 2000 to 2007. They all underwent conservative surgery followed by whole-breast irradiation or partial breast brachytherapy.

They found that brachytherapy became more common with time; nearly 1% of women were treated with brachytherapy in 2000, compared to 13% in 2007.

Dr. Smith said:

“We found that women treated with brachytherapy experience a twofold increased risk for subsequent mastectomy, indicating that women treated with brachytherapy were more likely to lose their breast after their initial breast-conserving therapy.”

The researchers found that:

  • 4% of the brachytherapy patients subsequently underwent mastectomy
  • 2.2% of the whole-breast irradiation patients subsequently underwent mastectomy

The researchers also found that the women who were treated with brachytherapy were more likely to experience side-effects linked to radiation compared to the whole-breast irradiation patients. Examples include breast pain, rib fracture and fat necrosis.

Smith and team said they were “shocked” by their findings.

Smith said:

“I think that our results are very plausible and consistent with the literature. However, I did not expect that we would find a difference in outcomes between brachytherapy and whole-breast irradiation using this claims-based approach. Such an approach has never been used before to evaluate breast brachytherapy.”

The team said their study is an example of how important it is to wait for mature data from randomized clinical trials before adopting breast brachytherapy in a big way.

Written by Christian Nordqvist