BOSTON – In women with in-breast failures following breast-conserving surgery and whole-breast irradiation, partial-breast irradiation with 3D conformal radiation appears to be an effective and safe alternative to mastectomy, results of a phase II trial indicate.
At a median follow-up of 3.6 years, there were only two ipsilateral breast recurrences, and four mastectomies required among 58 women treated with partial-breast irradiation after a second lumpectomy, reported Douglas W. Arthur, MD, chair of radiation oncology at Virginia Commonwealth University in Richmond.
Neil Osterweil/Frontline Medical News
Dr. Douglas W. Arthur
“I think this information adds to the growing data supporting this treatment approach as an alternative to mastectomy for those who continue to want to preserve the breast,” he said at a late-breaking abstracts session at the annual meeting of the American Society of Radiation Oncology.
The NRG/RTOG 1014 study is a prospective phase II trial designed to evaluate skin, breast, and chest wall events occurring within 1 year of re-irradiation. One-year toxicity results from the trial were reported at the 2015 ASTRO annual meeting.
Dr. Arthur presented 3-year efficacy results from the trial. The investigators enrolled women with in-breast recurrences more than 1 year after whole-breast irradiation (WBI), with tumors that were smaller than 3 cm, unifocal, and resected with negative margins. Axillary involvement was limited to pathologic NO or N1 without extracapsular extension.
Partial-breast irradiation was targeted to the surgical cavity with a safety margin of plus 1.5 cm for the clinical target volume, and an additional 1-cm expansion. The prescribed dose was 45 Gy in 1.5-Gy fractions delivered via 3D conformal radiotherapy in 30 treatments.
Of 65 patients accrued, 58 completed treatment and were evaluable for efficacy. The median age was 67.5 years. In all, 23 patients had ductal carcinoma in situ, and 35 had invasive cancers. All patients were node negative.
A total of four patients (6.9%) reported late grade 3 toxicities, which included breast infection, fibrous deep connective tissue, skin induration, and breast atrophy, pain, and volume loss. There were no grade 4 toxicities, and no treatment-related deaths.
Two patients had in-breast recurrences, which translated into a year estimate of 3.7%. Four patients underwent mastectomies, for a 3-year estimated mastectomy failure rate of 5.2%. Two of the mastectomies were for the in-breast recurrences, one for a nonhealing wound, and one occurred in a patient who developed cancer in the contralateral breast and opted for a bilateral mastectomy.