Boost Radiation Beneficial in Early-Stage Breast Cancer
In women with early-stage breast cancer who had been treated with breast-conserving lumpectomy and radiation, an additional “boost” dose of radiation to the original tumor site reduced the risk of cancer coming back in the same breast, though it did not help them live longer.
Journal of Clinical Oncology, published online June 18, 2007, and in print Aug. 1, 2007 (see the journal abstract).
(J Clin Oncol. 2007 Jun 18; [Epub ahead of print])
Studies have shown that for patients with stage I and stage II breast cancer, long-term survival is similar whether they have a lumpectomy (surgery that removes just the tumor and surrounding tissue) or a mastectomy (removal of the whole breast). Lumpectomy conserves the breast but also leaves open the possibility that cancer could recur there.
Radiation therapy after lumpectomy considerably reduces the risk of a relapse in the same breast. Often such radiation is given to the whole breast. Researchers in Europe decided to test whether a “boost” dose of radiation, given directly to the tumor bed (the site where the tumor had been) after a course of radiation therapy to the whole breast, would further reduce the risk of cancer coming back in the same breast.
More than 5,300 women from nine European countries joined this trial between 1989 and 1996. All of the women had had a lumpectomy followed by five weeks of radiation therapy to the whole breast. They were randomly assigned to receive either no additional treatment or a single boost of radiation to the tumor bed.
Preliminary results, published in 2001 after a median follow-up period of five years, showed that women who got the boost dose of radiation had a 41 percent lower risk of cancer coming back in the same breast than women who did not receive a boost dose (see the journal abstract). It was too early to tell, however, whether the boost dose improved patients’ long-term survival. The current study updates those findings after a median follow-up period of 10.8 years.
The principal investigator for both studies was Harry Bartelink, M.D., of the Netherlands Cancer Institute in Amsterdam.
Although the boost dose of radiation significantly reduced the risk of cancer coming back in the same breast, it did not help patients live longer overall.
After 10 years of follow-up, 81.7 percent of the women in both groups were still alive. The number of patients who developed second cancers or whose cancer spread to other organs was also the same in both groups.
Moderate to severe scarring of the breast occurred in 28.1 percent of the women who got the boost dose of radiation, compared with 13.2 percent of those who did not.
Of the women who received the boost dose of radiation, 6.2 percent had a recurrence of cancer in the same breast, compared with 10.2 percent of women who did not get the boost dose. As was the case with the earlier report, women who were aged 40 or younger at the time of treatment benefited the most from the boost dose.
Women who had a recurrence of cancer in the same breast were usually treated with mastectomy. Because there were fewer recurrences in the group of patients that received the boost dose of radiation, there was a 41 percent reduction in the number of mastectomies needed in that group.
Mastectomy may have saved the lives of those women who had a recurrence in the same breast, said the authors, and this may explain why there was no survival difference between women who got the boost dose of radiation and those who did not.
Deborah E. Citrin, M.D., of the National Cancer Institute’s Radiation Oncology Branch, agrees, adding that boost radiation for this patient population nonetheless offers some key benefits.
“Preventing a recurrence in the same breast is a very important goal after breast-conserving therapy,” she says. The addition of the boost dose of radiation meant that fewer patients needed a mastectomy because of a recurrence in the same breast and thus avoided the adverse physical and psychological effects of losing a breast.
Radiation therapy would not be expected to reduce second cancers or the spread of breast cancer to other organs, says Citrin. The slight increase in the risk of scarring from the additional dose of radiation must be weighed against the lower risk of recurrence and thus of the need for a subsequent mastectomy, Citrin adds.
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