Some cases of breast cancer overtreated

Sep 24 2008

According to a new study standard radiation therapy for some breast cancer patients may not be medically required and may, therefore, be causing unnecessary serious side effects.

The study suggests some breast cancer patients facing radiation after a mastectomy may be over-treated and suffering serious side effects such as lymphedema and pulmonary problems without good reason.

The research which was conducted at Fox Chase Cancer Center involved women who had a mastectomy, but whose lymph nodes were negative and the researchers say when a woman has a tumour greater than 5 centimeters and negative lymph nodes, a mastectomy followed by radiation is recommended.

Dr. Penny Anderson, from the radiation oncology department at Fox Chase, says usually the chest wall is irradiated because it has been shown to improve survival.

Dr. Anderson says as a precaution, many radiation oncologists also treat the surrounding lymph nodes, but there is little evidence that this improves the outcome.

The researchers say irradiation of the lymph nodes under arm and above the collarbone 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 the radiation.

They say 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 which involved 64 patients with node-negative breast cancer.

The women were 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 women were monitored for over six years and Anderson says they found an extremely low rate of recurrences in the lymph nodes among those who did not have them irradiated.

Dr. Anderson says of the 53 patients who received chest wall radiation but no radiation to the lymph nodes, only one developed a recurrence in an axillary lymph node and 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% for the group who received radiation to the chest wall and 100% for those who also received radiation to their lymph nodes and no statistically significant difference was seen between the local, regional or distant recurrence rates between the two groups.

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

The results were presented this week at the 50th annual meeting of the American Society for Therapeutic and Radiology Oncology in Boston.