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Adjuvant radiotherapy may prolong survival for elderly women with triple-negative breast cancer
The addition of adjuvant radiotherapy to lumpectomy prolonged OS and disease-specific survival among women aged older than 70 years with triple-negative breast cancer, according to study results scheduled for presentation at the 2015 Breast Cancer Symposium.
Sean Szeja, MD, radiation oncology resident, and Sandra S. Hatch, MD, faculty physician, both of University of Texas Medical Branch in Galveston, conducted this retrospective study to evaluate the effect of adjuvant radiation on survival for elderly women with triple-negative breast cancer. Although adjuvant radiation may be omitted for elderly women with ER-positive early-stage breast cancer who receive hormone therapy, its role was previously undefined in older women with triple-negative breast cancer.
Using the SEER database, Szeja and Hatch identified 974 women with triple-negative breast cancer aged 70 years or older who were diagnosed between 2010 and 2011 and who underwent a lumpectomy. All women had stage T1-2, N0, M0 disease.
Overall, 662 (68%) of the women received adjuvant radiotherapy.
A greater proportion of women who received radiotherapy plus lumpectomy were alive at 23 months compared with women who underwent lumpectomy alone (98.2% vs. 85.6%; P < .001).
Further, the rate of disease-specific survival appeared higher among women who received radiation (99% vs. 94%; P = .003).
Using a Cox regression model, Szeja and Hatch showed that adjuvant radiation improved OS (HR = 0.14; P < .001) and disease-specific survival (HR = 0.14; P = .01).
Researchers acknowledged selection bias may be a potential limitation to these findings.
Harold J. Burstein
“This study suggests that adjuvant radiation therapy may benefit some elderly patients with breast cancer, but a prospective study will be needed to guide treatment decisions,” Harold J. Burstein, MD, PhD, FASCO, senior physician at Dana-Farber Cancer Institute, associate professor of medicine at Harvard Medical School and an ASCO expert, said in a press release. “When selecting treatments for elderly patients, we need to be particularly careful about weighing the benefits and risks. – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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As we improve our adjuvant treatments for early-stage breast cancer — with excellent improvements for all patients in DFS and OS — we continuously seek to reduce toxicity of our therapies.
In particular, the treatment of elderly women with early-stage breast cancer can be challenging, because balancing competing causes of mortality in these women with the toxicity and efficacies of intervention is often part of the treatment decision.
Many of us, especially when confronted with a small (T1-T2) node-negative breast cancer in an older woman, often forego adjuvant radiotherapy. In ER-positive breast cancer, long-term follow-up of a recent ECOG study of adjuvant anastrozole with or without external beam radiation for T1-2 early-stage breast cancer in women aged older than 70 years suggested that radiation could be eliminated without a change in OS.
The question of whether radiation could also be safely eliminated for elderly women with ER-negative T1-2 breast cancer remained open. Now with this most recent presentation, there is a suggestion that for ER-negative T1-2 breast cancer in elderly women, radiation may provide a DFS and perhaps even an OS benefit.
The data suggesting this conclusion were derived from the SEER database, and are not the result of any randomized clinical trial or meta-analysis of clinical trials. In the SEER database, women aged 70 years or older who had segmental mastectomy for ER-negative breast cancer who received external beam radiation had a 23-month OS of 98.2% vs. 85.6% for those who did not have radiation (P ˂ .003).
The researchers correctly note that there was substantial selection bias in this analysis — that is, women who did not receive radiation in the SEER database perhaps had comorbidities severe enough to compromise survival from any cause.
Indeed, the difference in disease-specific survival was 99% in women who received radiation vs. 94% in those who did not, and this is not enough by itself to explain the OS difference. Therefore, more study is needed before we can proclaim that external beam radiation is needed for all women aged older than 70 years with early-stage ER-negative breast cancer.