Breast cancer radiation

Radiation therapy following surgical excision of the tumor has become the standard treatment for early breast cancer in women who want to avoid breast removal. Breast-conserving surgery (BCS), as it is known, followed by six weeks of radiotherapy has been offered as an alternative to mastectomy ever since 1985. That's when a large nationwide clinical trial showed that there was no difference in survival between the two treatments. But the same trial had randomly assigned participants to a third option: BCS without radiation therapy.

The third option isn't always offered to women because there is a higher rate of cancer recurrence in the affected breast for women not given radiation therapy. Still, there have been crucial lingering questions: Does the addition of radiation therapy to BCS prolong life? If so, by how much? And what about the small number of cardiac deaths associated with the radiation treatment itself?

These questions were explored in a new analysis of all relevant clinical trials published last month in the Journal of the National Cancer Institute (January 21, 2004). Altogether 13 clinical trials were assessed in which women with early breast cancer were treated with BCS alone or BCS plus radiotherapy. All had been treated between 1976 and 1994, but the follow-up period was only an average of six years.

The new analysis of these trials was conducted by Vincent Vinh-Hung, MD, Vrije Univeersiteit Brussel, Belgium and colleagues. The combined results came out in favor of radiation therapy. There was a small increase in survival (3%) among the women given radiation therapy and a large decrease in their recurrence rate. Since a recurrence usually leads to a mastectomy, the latter finding will have special import for women who want to do all they can to save their breasts.

The analysis confirmed the current practice of recommending radiation therapy to women who opt for BCS, according to an accompanying editorial by Katherine A Vallis, MD, and Ian F. Tannock, MD, Princess Margaret Hospital, Toronto. "Radiotherapy to the conserved breast (using modern techniques) probably [emphasis added] carries a minimal risk for cardiac toxicity."

Asked about "modern techniques," Dr. Vallis explained that improvements in radiation techniques have been introduced since many of the women in these trials were treated. Today, the radiation is more targeted, and therefore far less likely to cause heart damage, an adverse effect that would not show up for many years after the treatment. Dr. Vallis conceded, however, that the average followup period in these trials was too short (six years) to provide a definitive conclusion about whether radiation's benefit outweighs its potential risk. "That explains our use of the qualifying word probably in our editorial," acknowledged Dr. Vallis, by e-mail.

The research team that conducted the new analysis singled out the breast cancer patients whose odds of being harmed by the radiation are probably higher than the small odds of benefit: women with vascular disease and those who had been treated previously with radiation to the chest.