Radiation therapy (RT) does not increase the risk of lymphedema in patients with node-negative breast cancer beyond that of surgery, according to a secondary analysis of the NSABP (National Surgical Adjuvant Breast and Bowel Project) B-32 trial.
“These results should reassure breast cancer patients that radiation therapy to the level 1 axilla when radiating the whole breast does not contribute to lymphedema risk beyond surgery,” stated lead author Susan McCloskey, MD, of the David Geffen School of Medicine at the University of California Los Angeles. McCloskey added, “This analysis suggests that lymphedema should not be an impediment to women choosing breast conservation surgery and radiation therapy.”
The original study compared sentinel node biopsy (SNB) plus axillary node dissection (ALND) with SNB alone in 5611 women with no involved nodes.
Data from that trial were used to evaluate the impact of RT on the risk of lymphedema in those who underwent SNB or ALND. Ninety-three percent of the women underwent breast-conserving surgery and 97% received breast or chest wall–only radiation (nonregional node radiation).
Objective measurements (relative arm volume difference [RAVD]) were available for 3894 women (80% received RT), and subjective metrics were available for 730 women (80% had RT).
No impact of radiation was observed on physician-reported lymphedema based on RAVD or on patient-reported lymphedema in either SNB+ALND patients or SNB patients. At 36 months, lymphedema (RAVD >10%) was detected in 13% of the SNB+ALND group and 8% of the SNB group, with no difference between those treated with RT and those who did not have RT.
Interestingly, a lack of agreement was observed between patient-reported bothersome lymphedema and physician-measured lymphedema according to RAVD. At 36 months, 12.4% of the SNB+ALND and 7.4% of the SNB patients had measurable lymphedema on RAVD. Among these women, 7.4% and 3.2%, respectively, said their lymphedema was bothersome.
“We still have a lot to learn,” McCloskey stated.
McCloskey SA, Bandos H, Julian T, et al. The impact of radiation therapy on lymphedema risk and the agreement between subjective and objective lymphedema measures: NSABP B-32 secondary data analysis. Int J Radiat Oncol Biol Phys. 2014;90(1)(suppl):S4-S5. Presented at: 56th Annual Meeting of the American Society for Radiation Oncology; September 14-17, 2014; San Francisco, CA. Abstract CT-06.