Ultra-shortened radiation treatment with novel dosing schedule is tolerated
An ultra-shortened, accelerated breast irradiation treatment using a balloon device is both logistically achievable and tolerable.
Conventional courses of radiation treatment following breast cancer surgery commonly run for 7 to 8 weeks. There is reason to believe that patient comfort and convenience can be enhanced if the course of therapy is compressed into a single week, or less, with multiple treatments administered each day. This approach is known as accelerated partial breast irradiation (APBI). Investigators are now examining three such dosing schedules, which are delivered postsurgery in shorter courses than are commonly administered with APBI.
The investigators have now followed, for a minimum of 6 months, patients who received the first of those dosing schedules. This first cohort, consisting of women 50 years or older, were treated with four doses of 7 Gy twice daily through a catheter tube device inserted into the breast. The device, which delivers a radioactive seed to the affected area during each dose, has multiple treatment channels for the seed to travel in, ensuring a more precise target. The device remains in the breast for 2 days until the course is complete. The patients who participated had one invasive distinct tumor no larger than 3 cm that was surgically removed with no evidence of cancer cells on the outermost tissue, and with negative lymph nodes and positive hormone receptors.
What researchers found was that they were able to deliver this treatment while observing very strict restrictions on the doses to the skin and underlying ribs. Toxicities were minor and resolved with follow-up or minimal intervention. One breast infection occurred and was treated. Two cases of symptomatic fat necrosis and two cases of symptomatic seromas occurred. No acute toxicities greater than grade 2 were observed.
While full results of the study await administration and evaluation of the second and third short-course regimens, the portion of the trial completed to date has allowed investigators to make comparisons between results from the initial cohort and a recently unveiled European approach that delivers a single dose of radiation at the time of breast surgery while women are still under anesthesia. Although the approach has been found to be safe, it has stirred debate over a serious potential drawback: complete information on the tumor status is not available at the time of radiation because the pathology has not been reviewed.
That uncertainty may be eliminated in an acceptable way, according to Atif J. Khan, MD, of The Cancer Institute of New Jersey. “Our findings indicate that ultra-short courses of APBI with novel dosing levels can be logistically achieved and are well-tolerated,” said Kahn. He added, “While further study is needed, this important research offers women an abbreviated course of radiotherapy without the drawbacks of the single-dose intraoperative European approach.”
This research was presented at the CTRC-AACR San Antonio Breast Cancer Symposium, held December 4-8, 2012.