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Study suggests some breast cancer patients facing radiation after a mastectomy may be over-treated

September 22, 2008

BOSTON -- A new study suggests standard radiation therapy for some breast cancer patients may not be medically required and may, therefore, be causing unnecessary serious side effects such as lymphedema and pulmonary problems. The research conducted at Fox Chase Cancer Center involved women who got a mastectomy, but whose lymph nodes were negative.

"When a woman has a tumor greater than 5 centimeters and negative lymph nodes, a mastectomy followed by radiation is recommended," said Penny Anderson, M.D., attending physician in the radiation oncology department at Fox Chase. "We typically irradiate the chest wall because it's been shown to improve survival. Out of an abundance of caution, many radiation oncologists also treat the surrounding lymph nodes, but there is little evidence that this improves outcome."

Irradiation of axillary (under arm) and supraclavicular (above the collarbone) lymph nodes can lead to lymphedema, a swelling of the extremities caused by fluid build up because the nodes which allow the fluids to drain have been damaged by radiation. There are also pulmonary radiation risks including pneumonitis, inflammation, scarring and fibrosis.

For the study, Anderson and her colleagues evaluated the need for irradiating these lymph nodes in women whose axillary nodal status following surgery was negative.

The study included 64 patients with node-negative breast cancer treated by mastectomy and radiation from 1985-2006. Fifty-three patients received radiation therapy to the chest wall only and 11 patients received radiation to the regional lymph nodes in addition to the chest wall. The median follow-up was 78 months. The results were presented at the 50th annual meeting of the American Society for Therapeutic and Radiology Oncology in Boston.

"We found an extremely low rate of recurrences in the lymph nodes among those who didn't have them irradiated," said Anderson.

In fact, Anderson added, of the 53 patients that received chest wall radiation but no radiation to the lymph nodes, only one developed a recurrence in an axillary lymph node. None of the patients who received chest wall and node radiation had a recurrence.

The 5-year overall survival rates for the two groups were 91 percent for group who received radiation to the chest wall and 100 percent for those who also received radiation to their lymph nodes. There was no statistically significant difference noted between the local, regional or distant recurrence rates between the two groups.

"Given these findings and the risks of lymphedema and pulmonary toxicity, avoiding irradiating the lymph nodes may be an acceptable approach in select patients," Anderson concludes.

Fox Chase Cancer Center