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Nodal radiation therapy improved breast cancer outcomes
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Postoperative radiation therapy to the internal mammary and medial supraclavicular lymph nodes extended survival in patients with lymph node-involved breast cancer, according to study results presented at the European Cancer Congress.
Researchers enrolled 4,004 patients (median age, 54 years) between 1996 and 2004. Eligible patients had involved axillary lymph nodes (55.6%) or a medially located primary tumor. The majority of the cohort (59%) were postmenopausal.
More than half of patients (52%) had stage II breast cancer, 33.8% had stage I disease and 14.2% had stage III breast cancer.
Most patients (76.1%) had been treated with breast-conserving therapy; of them, 85.1% received a boost to the primary tumor bed.
Researchers randomly assigned patients to radiation treatment to the internal mammary and medical supraclavicular lymph nodes in 25 fractions totaling 50 Gy or no radiation treatment.
Overall, 73.2% of the patients underwent chest wall irradiation after mastectomy. Among patients who were lymph node-positive, 99% received adjuvant systemic treatment vs. 66.3% who were lymph node-negative.
More patients in the radiation treatment arm received axillary radiation therapy compared with the control arm (7.8% vs. 6.8%).
OS served as the primary outcome measure. DFS, metastases-free survival and cause of death were secondary endpoints.
After a median follow-up of 10.9 years, 811 patients died; of them, 382 were in the radiation treatment group and 429 had been assigned to no radiation treatment.
The rate of 10-year OS was higher among patients assigned to nodal radiation therapy (82.3% vs. 80.7%; HR=0.87; 95% CI, 0.76-1.00), as were rates of 10-year DFS (72.1% vs. 69.1%; HR=0.89; 95% CI, 0.80-1.0) and 10-year metastases-free survival (78% vs. 75%; HR=0.86; 95% CI, 0.76-0.98).
The treatment effect on OS was consistent regardless of the number of lymph nodes involved and lymph node negativity (HR=0.79; 95% CI, 0.61-1.02). Researchers calculated HRs of 0.89 (95% CI, 0.73-1.09) for one to three affected lymph nodes; 0.85 (95% CI, 0.61-1.18) for four to nine affected lymph nodes; and 1 (95% CI, 0.59-1.71) for 10 or more affected lymph nodes.
Causes of death were similar between the two groups; however, the total number of deaths was higher among the group that did not receive nodal radiation (310 vs. 259).
The additional radiation did not increase fatal complications, researchers said.
“It looks like the regional intensification of treatment is most effective in patients who have the lowest risk for metastasis, either because they have a lower disease burden, low nodal involvement, or because they were treated more effectively with systemic treatment, effectively killing the already microscopically spread disease outside of the breast and the lymph nodes,” researcher Philip Poortmans, MD, PhD, a radiation oncologist at the Institute Verbeeten in Tilburg, The Netherlands, said during a press conference. “This has to be further analyzed, but it looks like the better we treat already-present metastasis, the better we can improve outcome with an optimizing of local regional disease.”
For more information:
Poortmans P. Abstract #E17-2211. Presented at: The European Cancer Congress 2013. Sept. 27 – Oct. 2, 2013; Amsterdam.
Disclosure: See the study for a full list of the researchers’ relevant financial disclosures.
Perspective
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Cornelis van de Velde, MD, PhD
In past studies, radiotherapy as an adjunct to surgery has shown important improvements in locoregional control as well as survival, and these further survival benefits without an increase in short- and long-term toxicities are a valuable development. The results of this study will help us on the road to the development of yet more personalized treatments, in which we have to find the delicate balance between undertreatment — resulting in an increased risk of disease recurrence — and overtreatment — accompanied by unnecessary toxicity — in order to provide optimal care for breast cancer patients.
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