San
Antonio Breast Cancer Symposium
SAN ANTONIO — Accelerated partial-breast brachytherapy was inferior
to whole-breast irradiation and also was associated with increased acute and
late toxicities, researchers from The University of Texas MD Anderson Cancer
Center said here.
“Accelerated partial-breast brachytherapy is an increasingly
popular radiation treatment for older patients diagnosed with early-stage
breast cancer,” said Benjamin D. Smith, MD, assistant professor in
the department of radiation oncology at MD Anderson Cancer Center.
“Despite growing utilization, there is a lack of population-based cohort
studies, as well as randomized phase 3 data, to compare its effectiveness and
toxicity profile with standard whole-breast irradiation.”
The researchers used Medicare billing claims to identify patients aged
older than 66 years with incident invasive breast cancer who were diagnosed
between 2000 and 2007. The patients were treated with conservative surgery
followed by accelerated partial-breast brachytherapy or whole-breast
irradiation. The researchers compared the incidence of
mastectomy between the groups, the risk for acute toxicities
and the cumulative incidence of long-term toxicity.
In 130,535 women, the use of accelerated partial-breast brachytherapy
increased from less than 1% of patients in 2000 to 13% of patients in 2007.
These women were less likely to have axillary lymph node involvement and to
have received chemotherapy, but were more likely to be older, white and have
comorbidities.
At 5 years, the incidence of subsequent mastectomy was 4% in those
treated with accelerated partial-breast brachytherapy vs. 2.2% in those treated
with whole-breast irradiation (P<.001). Accelerated partial-breast
brachytherapy also was associated with more acute complications, including a
higher risk for hospitalization and infection. Accelerated partial-breast
brachytherapy also was associated with a higher 5-year incidence of rib
fracture, fat necrosis and breast pain, but a lower incidence of pneumonitis.
“These data underscore the importance of awaiting mature results of
randomized trials designed to prospectively compare these treatments before
employing widespread adoption of accelerated partial-breast brachytherapy as an
alternative to whole-breast irradiation in select patients,” Smith said.
Disclosure: Dr. Smith reports no relevant financial disclosures.
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.
For more information:
- Smith G. #S2-1. Presented at: the 2011 CTRC-AACR San Antonio Breast
Cancer Symposium; Dec. 6-10, 2011; San Antonio.
This is the first study of this type that has looked at a larger
population. There are several parts that are interesting. The recurrence rate
is slightly higher in patients who had the partial-breast brachytherapy;
however, the numbers are not huge. To go from a 2% rate to a 4% rate is still a
low risk. It tells you that we need to have some prospective data, and
hopefully, we will get that information soon with the NSAPB B39 study. To get
that information is crucial before we open the Pandora’s box. Another
interesting part of this study was the data on complications. Some of the
complications continued, even up to 18 months afterward. It says we need to be
particularly cautious in evaluating complications in people who are receiving
this treatment now. However, the data were collected earlier in the time frame,
so what we don’t know is whether there is a learning curve. Many people
who were treated in this early part of the study time frame may have had more
complications because we weren’t aware of these potential complications
that may be prevented by paying attention to different subtleties in the
techniques. These are exciting data, but it serves as a cautionary reminder
that we need to think carefully when offering this treatment to a patient not
in a study situation.
Ivy A. Petersen, MD
Associate Professor of
Radiation Oncology, Mayo Clinic, Rochester, Minn.
Disclosure: Dr. Petersen reports no relevant financial
disclosures.