Regional nodal irradiation reduced recurrence in high-risk early breast cancer

Issue: July 10, 2011

2011 ASCO Annual Meeting

CHICAGO – The addition of regional nodal irradiation improved recurrence and disease-free survival in women at high-risk for breast cancer according to interim results from the phase-3 MA-20 trial.

Timothy J. Whelan, BM BCh, division head of radiation oncology at McMaster University and the Juravinski Cancer Centre, Hamilton, Ontario, said results for OS, the study’s primary endpoint, did not reach statistical significance, but showed a trend towards improvement.

“Currently, women with node-positive breast cancer are treated with whole breast irradiation following breast conserving surgery. Women with larger tumors or more than three positive lymph nodes are also offered regional nodal irradiation,” Whelan said during a Saturday press conference at the 47th ASCO Annual Meeting. “These results from MA-20 suggest that all women with node positive disease be offered regional nodal provided they are made aware of the associated toxicities.”

Whelan added that he expects final results will show a statistically significant improvement in OS associated with WBI plus regional nodal irradiation.

From March 2000 to March 2007, 1,832 women with high-risk node-positive or node-negative breast cancer were stratified by positive nodes, axillary nodes removed, chemotherapy and endocrine therapy. Patients were then randomly assigned to 50 Gy whole breast irradiation 25 fractions (n=916) or WBI plus 45 Gy regional nodal irradiation to the internal mammary supraclavicular, and high axillary lymph nodes in 25 fractions (n=916).

At a median follow-up of 62 months, patients assigned to WBI plus regional nodal irradiation had a 30% improvement in DFS (84.0% vs. 89.7%), a 41% lower rate of local recurrence (5.5% vs. 3.2%) and a 36% lower rate of distant recurrence (13.0% vs. 7.6%)

WBI plus regional nodal irradiation was associated with an increase in grade-2 or greater pneumonitis (1.3% vs. 0.2%) and lymphedema (7.3% vs. 4.1%). – by Jason Harris

Whelan TJ. #LBA1003. Presented at: 2011 ASCO Annual Meeting; Chicago; June 3-7, 2011.

Disclosure: Dr. Whelan reported no relevant financial disclosures.

These randomized phase-3 results show we can reduce risk for local recurrence and improve disease-free survival with radiation to the lymph nodes in women who we did not previously consider for this therapy. This study, in a much more definitive fashion, shows us that radiation to the lymph nodes can reduce the risk for breast cancer recurrence and decrease local recurrence. We always knew that was the case in women with more than three lymph nodes. This study evaluated women with one to three lymph nodes, who we previously treated with whole breast irradiation. We’ve never been able to demonstrate that radiation of the nodes can reduce risk for recurrence.

- Jennifer C. Obel, MD
Medical Oncologist, NorthShore University Health System, Chicago

Disclosure: Dr. Obel reported no relevant financial disclosures.

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