External-beam radiation therapy safe for breast cancer

Nov 8 2006

External-beam radiation therapy for early-stage breast cancer can be delivered safely and in a shorter course that eliminates as much as two weeks from conventional treatment, finds a Fox Chase Cancer Center study presented at the 48th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Philadelphia.

Many women with early-stage breast cancer are treated with breast-sparing surgery (lumpectomy) followed by external-beam radiation. The typical radiation course is delivered five days a week for six to seven weeks. In this phase II study presented today, researchers demonstrated that treatment length can be safely shortened to four weeks by increasing the daily dose delivered to the breast and lumpectomy site.

A standard "boost," or increased dose, to the lumpectomy site usually takes an additional one and one-half to two weeks after the whole breast is treated with a standard radiation regimen. This study showed that the boost can be worked into a four-week course with similar side effects when compared to the longer standard treatment. Women reported acceptable side effects of breast or arm pain and high satisfaction with cosmetic results.

"We know the standard regimen of daily radiation five days a week for six to seven weeks is a tremendous time commitment for women who are often still working or providing family care or both," said the study's lead author Gary Freedman, M.D., a radiation oncologist at Fox Chase Cancer Center in Philadelphia. "Our goal in this research was to reduce the burden of treatment time while maintaining a high level of quality of life issues."

This is the first known study of its kind for breast cancer treatment involving intensity-modulated radiation therapy or IMRT. IMRT is a highly sophisticated system of delivering external-beam radiation that allows advanced planning for accuracy and reduced side effects.

For the study, physicians administered a dose of radiation with IMRT to the entire breast for four weeks (20 daily treatments). During the same period, they added a radiation boost, a little each day, to the part of the breast where the tumor was removed (tumor bed). Because the boost is normally given for seven to 10 treatment fractions extra, the physicians were able to eliminate two weeks of treatment time.

The study included 75 patients and the end goal was to measure toxicity and cosmetic outcomes. Scores for toxicity and cosmetic outcomes were compared with historical data of women who received the usual longer course of therapy.

Toxicity results

The maximum dermatitis (skin inflamation) at the end of treatment was 12 percent with grade 0, 65 percent with grade 1, 23 percent with grade 2, and 0 with grade 3 or 4. Comparisons to women receiving conventional treatment used historical controls from the Radiation Therapy Oncology Group (8 percent with grade 0, 54 percent with grade 1, 36 percent with grade 2, and 1 percent with grade 3), and historical controls from Fox Chase (1 percent with grade 0, 21 percent with grade 1, 71 percent with grade 2, 8 percent with grade 3, and 1 percent with grade 4). By six weeks after treatment, all toxicity had resolved to a grade 0 or 1.

Cosmetic results

Patients were asked to score their cosmetic result by comparing their treated breast with the untreated breast. The mean cosmesis scores were no different at six weeks, eight months, or one year after the treatment.

Pain results

Patients were asked to score pain in the same way. Mean pain scores were higher at six weeks and eight months versus baseline, but scores were generally mild and women did not require pain medication. "These results demonstrate that the increased daily radiation given to the breast does not result in significant increased side-effects, but it allows us to dramatically reduce the time needed for treatment," explained Freedman.

"Longer follow-up is needed to compare the outcomes at five years after treatment."