January 10, 2020
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Partial breast reirradiation ‘viable alternative to mastectomy’ for certain women with breast cancer recurrence

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Partial breast reirradiation without mastectomy appeared as effective as mastectomy for treatment of breast cancer recurrence in the ipsilateral breast after lumpectomy and whole breast irradiation, according to results of the phase 2 NRG Oncology/RTOG1014 trial published in JAMA Oncology.

“The idea for this study was introduced by patients confronting a new cancer in the same breast previously treated with whole breast irradiation who did not want to have a mastectomy,” Douglas W. Arthur, MD, FABS, FASTRO, professor and chairman in the department of radiation oncology at Virginia Commonwealth University School of Medicine, told Healio. “We know that lumpectomy alone in these patients is insufficient and repeat whole breast irradiation risks unacceptable toxicity. However, based on the experience with partial breast treatment for early-stage breast cancer, we took the opportunity to evaluate an approach that could be effective, safe and avoid mastectomy.”

The study included 58 women (mean age, 65 years; 82.8% white) who experienced in-breast local recurrence of cancer (3 cm or less) at least 1 year after lumpectomy with whole breast irradiation and who had undergone excision with negative margins.

More than half (60%) of breast cancer recurrences in the ipsilateral breast were invasive. Ninety-one percent of all women had tumors no larger than 2 cm, and all tumors were clinically node negative. The majority (76%) of women had ER-positive tumors, whereas 57% were PR-positive and 17% were positive for ERBB2 overexpression.

All women underwent partial breast reirradiation with 3D conformal radiotherapy at a dose of 1.5 Gy twice daily on 15 consecutive days, for a total dose of 45 Gy in 30 fractions to the defined partial breast area.

Median follow-up was 5.5 years (range, 0.1-7.2).

Results showed that four women had breast cancer recurrence, with a 5-year cumulative incidence of 5% (95% CI, 1-13). Seven women underwent ipsilateral mastectomy, 5-year cumulative incidence of which was 10% (95% CI, 4-20). DFS and OS rates were both 95% (95% CI, 85-98).

Grade 3 adverse events occurred among 7% of women, and researchers observed no grade 4 adverse events.

Limitations of the study included the fact that the sample size required for the single-arm phase 2 trial did not allow for analyses to discern whether certain subgroups would be at higher risk for re-recurrence with this partial breast reirradiation technique.

“This is exciting data for women experiencing an in-breast recurrence after an initial lumpectomy and whole breast irradiation who desire to continue to preserve their breast,” Arthur told Healio. “These women now have a breast-conserving treatment choice that is a viable alternative to mastectomy. The trial results presented relied on a radiation delivery approach that treated twice daily for 3 weeks. The logistics of this were difficult for some patients. Subsequent research might focus on how to deliver this partial breast treatment in a more convenient approach.”

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The NRG Oncology/RTOG1014 trial provides justification to offer second breast-conservation therapy with partial breast reirradiation to carefully selected women with in-breast recurrence after lumpectomy and whole breast irradiation, Kiri Cook, MD, researcher in the department of radiation medicine at Oregon Health and Science University, and Maggie DiNome, MD, researcher in the department of surgery at University of California, Los Angeles, wrote in an accompanying editorial.

“This work also uncovered a number of avenues for future investigation, such as finding the balance between toxic effects and patient convenience,” Cook and DiNome wrote. “In addition, assessing whether margins wider than no tumor on ink would be beneficial to decrease rates of second recurrences, given that the four recurrences noted in this study were of ductal carcinoma in situ. ... Finally, improvement of patient selection criteria would be of benefit. Future studies would ideally contain patient-reported outcomes for a more robust assessment of toxic effects.” – by Jennifer Southall

For more information:

Douglas W. Arthur, MD, FABS, FASTRO, can be reached at Virginia Commonwealth University, P.O. Box 980058, Richmond, VA 23298; email: douglas.arthur@vcuhealth.org.

Disclosures: The study was supported by grants from the NCI Community Oncology Research Program, NRG Oncology Statistics and Data Management Center, NRG Oncology Specimen Bank and Imaging and Radiation Oncology Core of the NCI. Arthur reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures. Cook and DiNome report no relevant financial disclosures.