DENVER — Whole-breast irradiation coupled with breast-conserving surgery and hormone therapy remains the standard of care in women with favorable early breast cancer, Richard Poetter, M.D., said at the annual meeting of the American Society for Therapeutic Radiology and Oncology.
New data from a large multicenter randomized Austrian trial demonstrate that although lumpectomy plus 5 years of tamoxifen or an aromatase inhibitor provides “excellent” results in such patients, “we can do significantly better if we add whole-breast radiotherapy,” said Dr. Poetter of the University of Vienna.
But this assertion was challenged by discussant Kevin S. Hughes, M.D., who argued that the benefits conferred by the addition of radiation therapy (RT), while statistically significant, are modest and do not rise to the level of clinical significance or warrant standard-of-care status.
He urged an individualized approach to breast RT, a treatment he said most elderly patients are best spared.
“Breast radiation therapy provides less and less benefit as women get older,” said Dr. Hughes, surgical director of the Avon Foundation Comprehensive Breast Evaluation Center at Massachusetts General Hospital, Boston.
“Most radiation oncology colleagues I know would agree that in elderly patients, breast irradiation plus tamoxifen or an aromatase inhibitor is overkill and is seldom required. Where we disagree is in deciding who are the elderly.”
Dr. Poetter reported on 826 postmenopausal women with favorable early breast cancer as defined by a tumor size less than 3 cm, negative lymph nodes, and positive tumor estrogen and/or progesterone receptor status. All underwent lumpectomy plus hormone therapy and were randomized to whole-breast RT or not in the Austrian Breast and Colorectal Cancer Study Group trial 8. Patients in the RT arm received 50 Gy to the breast; two-thirds of them got an additional 10-Gy boost.
After a median 42 months' follow-up, the 5-year local recurrence rate—the primary study end point—was 4.5% in controls, compared with 0.6% in the RT group. The risk of local relapse was increased 13.5-fold by lack of RT.
Dr. Hughes, however, flipped those figures around, noting the Austrians had shown that more than 96% of study participants who were exposed to the cost, inconvenience, and potential toxicities of RT derived no benefit from it. “Perhaps a more intelligent way of looking at these older patients is to say 'lumpectomy plus radiation therapy' or 'lumpectomy plus tamoxifen.' Both give very good outcomes as patients age.”
Dr. Poetter noted that four cases of contralateral breast cancer arose among controls, versus none in the RT group. However, RT had no significant impact upon distant metastasis or overall survival rates.
The 42-month follow-up in the Austrian trial is relatively brief, Dr. Hughes said. More mature 7-year data are now available from the similarly designed Cancer and Leukemia Group B trial 9343, in which he was the lead investigator. Five-year data already have been reported from the trial, in which 636 women aged 70 years or older with favorable early breast cancer treated by lumpectomy and tamoxifen were randomized to RT or not (N. Engl. J. Med. 2004;351:971–7).
At 7 years, 99% of women in the RT arm remain disease free, compared with 94.4% with lumpectomy and tamoxifen alone. “But whether you irradiate or not, essentially 98%–99% of those women will preserve their breast through the remainder of their lives,” the surgeon said.
A total of 24% of study participants have died; 1% of breast cancer, the other 23% of other causes.