Meta-Analysis Backs Nodal Radiation in Early Breast Cancer

TOPLINE:

Regional node radiotherapy significantly reduces both disease-specific and all-cause mortality in women with early breast cancer.

METHODOLOGY:

• Researchers wanted to explore the effects of irradiating regional lymph nodes after surgery for early breast cancer among individual trials published over the past six decades.

• Investigators performed a meta-analysis of randomized trials that pitted regional lymph node radiotherapy against no regional lymph node radiotherapy among patients with early breast cancer.

• The goal of the analysis was to assess the impact of irradiating the internal mammary chain, supraclavicular fossa, and axillary lymph nodes on breast cancer recurrence as well as breast cancer, non-breast cancer, and all-cause mortality.

• The team identified eight trials starting between 1961 and 1978 that included 2157 women, and eight trials starting between 1989 and 2008 that included 12,167 women.

• The newer trials incorporated advances in tumor targeting and lung/heart sparing. Over half of the women in the more recent trials underwent breast-conserving surgery with breast irradiation. Most women who had undergone mastectomy also underwent chest wall irradiation, both of which usually included lower axilla radiation.

TAKEAWAY:

• In the eight older trials, regional node radiotherapy had little effect on breast cancer mortality (rate ratio [RR], 1.04; 95% CI, 0.91 – 1.20), but it was associated with a significant increase in non-breast-cancer mortality (RR, 1.42; P=.00023), with the risk mainly occurring 20 years after treatment.

• In the eight newer trials, regional node radiotherapy significantly reduced breast cancer recurrences, particularly distant recurrences (RR, 0.88; P = .0008), as well as breast cancer mortality (RR, 0.87; P = .0010) and all-cause mortality (RR, 0.90; P = .0022), but it no significant impact on non-breast-cancer mortality (RR, 0.97; 95% CI, 0.84 – 1.11).

• Regarding the eight newer trials, the researchers reported absolute reductions in 15-year breast cancer mortality of 1.6% for women with no positive axillary nodes, 2.7% for women with one to three positive axillary nodes, and 4.5% for those with four or more positive axillary nodes.

• Most of the benefits of radiotherapy came from radiation to the internal mammary chain or to the internal mammary chain plus the supraclavicular fossa. The authors reported some evidence that the benefit was greater for women with medial or central tumors rather than lateral tumors.

IN PRACTICE:

• "Regional node radiotherapy significantly reduced breast cancer mortality and all-cause mortality in trials done after the 1980s, but not in older trials," the authors concluded. They note that "these contrasting findings could reflect radiotherapy improvements since the 1980s" and that clinicians and patients can use the latest evidence "to estimate survival gains from regional node radiotherapy in shared decision making."

SOURCE:

The study, led by Carolyn Taylor and David Dodwell of the Early Breast Cancer Trialists' Collaborative Group, was published November 3 in The Lancet.

LIMITATIONS:

Uncertainty remains about the benefits of regional node radiotherapy for women who receive neoadjuvant therapy.

DISCLOSURES:

The study was funded by Cancer Research UK and the Medical Research Council. The investigators reported ties to many pharmaceutical companies and other companies, including Roche, AstraZeneca, and Pfizer.

M. Alexander Otto is a physician assistant with a master's degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape. Alex is also an MIT Knight Science Journalism fellow. Email: aotto@mdedge.com .

Medscape Medical News © 2023 WebMD, LLC

Send comments and news tips to news@medscape.net.

Cite this: Meta-Analysis Backs Nodal Radiation in Early Breast Cancer - Medscape - Nov 13, 2023.