2011 Breast Cancer Symposium
SAN FRANCISCO - After accelerated partial-breast irradiation, 5-year
local control rates were excellent for patients with a variety of breast cancer
subtypes in early-stage breast cancer, according to research presented here at
the 2011 Breast Cancer Symposium.
J. Ben Wilkinson, MD, a resident in radiation oncology at Oakland
University William Beaumont School of Medicine, and colleagues evaluated 516
consecutive patients who received accelerated
partial-breast irradiation with a minimum follow-up of 6
months. The women were assigned a breast cancer subtype based on results of
testing for ER, PR and HER-2 receptors. Women were excluded if there was
missing data; 278 patients remained eligible.
The subtypes were: luminal A (ER+, PR-/+, HER-2-negative); luminal B
(ER+, PR-/+, HER-2-positive); H2 (ER-, PR-, HER-2-positive); and basal (ER-,
PR-, HER-2-negative). Luminal A patients comprised 59% of the patients, luminal
B patients comprised 29% of the patients, H2 patients comprised 2% of the
patients and basal patients comprised 10% of the patients.
Luminal A and luminal B subtypes were associated with higher tumor grade
and increased use of chemotherapy. The basal subtype was associated with
younger patients, higher grade, increased tumor size and black patients. There
were no significant differences in recurrence patterns or survival.
"Further study of breast cancer subtypes is important and may be useful
when counseling patients on adjuvant radiation treatment options following
breast-conserving surgery," Wilkinson said.
For more information:
Disclosure: Dr. Wilkinson reports no relevant financial
Partial breast irradiation offers women a 5-day alternative to radiation instead of the conventional 6.5 weeks of whole breast irradiation. It limits radiation exposure to other parts of the body and collateral damage to the heart, lung, ribs, muscles and skin. It's a very exciting realm of research. Unfortunately, the studies started 20 years ago and most of the investigators chose only the most favorable patients for the clinical trials studying partial breast irradiation. Patients tended to be older women with lower grade tumors and no adverse pathologic features. When the National Cancer Institute reviewed the data, they concluded that there were no negative data about using partial breast irradiation to treat women younger than 50 years with grade 3 tumors and lobular histologies and other adverse pathologies. They concluded that there was not enough evidence to offer the unfavorable breast cancers partial breast irradiation, even though there was no negative data.
The current NSABP B-39 trial includes unfavorable cancers, and it's a head-to-head comparison of the 6 weeks vs. 5 days protocol, so we will have an answer in about 2 years. The question is, what do we do in the interim? We put out a call to people investigating partial breast irradiation, including the group that conducted this study. Study after study, including this one and a study from the University of Wisconsin and others, have shown that when looking at these subsets of women, partial breast irradiation is doing quite well. I'm very glad to see this study being published, which shows that even younger women with aggressive breast cancer may have a 5-day alternative to the 6.5 weeks. This study is potentially practice changing because people read that unsuitable label, but they don't read that it is only unsuitable if not on clinical trial. When I see a patient who is aged younger than 50 years, maybe with positive sentinel nodes, I try to convince them to be part of the clinical trial. Hopefully these hesitant physicians will now open the floodgates and will put these patients onto clinical trials in these subtypes.
– Robert R. Kuske, MD,
Medical director for Arizona Breast Cancer Specialists,
Earn CME this spring at the HemOnc Today Breast Cancer Review & Perspective meeting to be held March 23-24, 2012 at the Hilton San Diego Bayfront. See details at HemOncTodayBreastCancer.com.