21 November 2019

Following lumpectomy, radiation therapy to the whole breast is a standard part of breast conserving therapy (BCT). The use of radiation therapy after lumpectomy has been shown to reduce local (in the breast) recurrence rates. Radiation therapy can be administered in several ways, but most commonly, the whole breast is treated (whole breast irradiation, WBI). Treatments are usually administered 5 days per week, over the course of 3-6 weeks, depending on the specific protocol that is followed.

One of the disadvantages to this approach is that if there is a recurrence of cancer in the breast after treatment, mastectomy is usually recommended due to concerns about wound healing problems as well as toxicity from administering radiation a second time. However, newer techniques and the ability to target the lumpectomy site more precisely may give some women who develop a recurrence after initial BCT another option.

The results of the NRG Oncology / RTOG 1014 study were recently published in JAMA Oncology*. Patients who initially underwent BCT and developed a recurrence greater than one year from initial treatment that was ≤3cm and was unifocal (one area of disease) were eligible to participate. All patients underwent surgical removal of the recurrence with clear margins. Following surgery, external beam radiation, focused to the lumpectomy site, was administered. The study enrolled patients from 2010 – 2013 and follow up through 2018 was included in this publication. Median follow up was 5.5 years.

65 patients were enrolled, and 58 were evaluable. Of those, 91% had tumors ≤2cm (median tumor size 1.0cm) and none had suspicious lymph nodes. 23 (40%) had DCIS and 35 (60%) had invasive cancer. 44 (76%) had ER+ tumors. Of these 58 patients, 4 developed yet another recurrence, all non-invasive, for a 5-year local recurrence rate of 5%. A total of 7 patients underwent mastectomy – 4 with recurrent disease, 2 due to wound healing complications, and one in a patient who developed cancer in the other breast and subsequently underwent a bilateral mastectomy. Both metastasis-free survival and overall survival was 95%. Toxicities were mostly graded as minor.

The conclusion of the authors was that external beam partial breast re-irradiation is “an effective alternative to mastectomy” in select patients who develop a local recurrence after BCT. Drs. Cook and DiNome, in an accompanying editorial*, note some of the limitations of the study: patients were older, mostly white, with relatively small low-grade tumors. Therefore, the results may not be applied to all patients. However, they agree that for selected patients who are motivated to avoid mastectomy in the setting of recurrence after BCT, partial breast re-irradiation is a reasonable option to consider.

*If you are not able to access the full study and would like a copy, please email me: contact at drattai dot com