Dr. Kuske's Viewpoint on the MD Anderson Presentation in San Antonio
On December 13, 2011, four of the world's leading clinical researchers in breast brachytherapy gathered to provide statements and discuss a controversial new study on APBI presented at the 2011 San Antonio Breast Cancer Symposium. Dr. Kuske was among those present. The study was based on Medicare billing claims for more than 130,000 patients over the age of 66 who were diagnosed with early stage breast cancer between 2000 and 2007 and received a lumpectomy and radiation.
Many members of the medical community have spoken out against the study since it was presented. In particular, many physicians object to mastectomy being considered a validated surrogate for local failure, contending that there are many indications for mastectomy unrelated to APBI, such as a new primary cancer or elsewhere failure, and that claims data do not provide sufficient clinical information to draw such conclusions. In addition, the study claimed brachytherapy was associated with higher rates of infection and increased toxicity which is contrary to results of several published clinical trials on brachytherapy.
Background: Partial breast irradiation(PBI) began in New Orleans in 1991 by myself and colleagues at the Ochsner Clinic, and has been one of the most studied treatments for breast cancer over the past 20 years. Numerous publications have shown PBI to be safe and effective for select early stage breast cancer patients. As a result of promising phase 2 clinical trials and two favorable randomized prospective clinical trials (scientifically the "Gold Standard"), there has been growing interest in using PBI. PBI treats only the part of the breast affected by cancer and the treatment time is decreased from several weeks to four or five days. For decades, whole-breast irradiation (WBI), where radiation is delivered every day for five to eight weeks, has been the standard treatment for patients with early breast cancer treated with breast conserving surgery.
APBI has several benefits, including a decreased overall treatment time and a decrease in the radiation delivered to healthy tissue and adjacent organs. To document its long-term safety and effectiveness compared to WBI, we await the results of the other 7 randomized trials comparing APBI with WBI.
I am concerned about the potential misinterpretation of data presented last week at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium regarding breast cancer patients who received brachytherapy, or accelerated partial breast irradiation (APBI).
This data have serious limitations, and should not influence current treatment recommendations for women with early stage breast cancer fitting current eligibility criteria for PBI.
This study, based on Medicare claims data, demonstrated a small 1.8% increase in the rate of mastectomies in patients treated with APBI compared with those treated with conventional whole breast external beam irradiation. Note that the rate of documented recurrences of breast cancer after treatment is not reported. In either case, the rate of mastectomy is still very low (2.2 to 4%), and should be contrasted with the 35 to 40% recurrence rate after lumpectomy without any radiotherapy.
The data presented in San Antonio was drawn from records of patients varying risk factors and stage treated between 2000 and 2007. Doctors choose treatments for their patients based on cancer extent, grade, surgical margins, and other factors such as obesity, diabetes, and age. This study failed to take these important tumor and patient issues into account, and is therefore biased. This study is a good example of why it is important to be selective in choosing which patients receive the accelerated treatment.
The PBI treatment given in this study is an antiquated balloon catheter with a single channel. Since that time, technology has dramatically improved including the use of newer multichannel applicators with tighter dose constraints. The side effects and toxicity seen with these modern technological advances is far better than the results presented in this study.
This study should encourage enrollment in clinical trials, especially NSABP B-39/RTOG 0413, an NCI-sponsored randomized prospective phase 3 trial. In the meantime, doctors and patients should not limit their options for a 5-day alternative to conventional 6-7 weeks of whole breast irradiation to conserve the breast.