SAN ANTONIO — The use of radiotherapy following breast-conserving surgery for invasive cancer is declining in the United States—and that's a trend spelling trouble, Beth A. Virnig, Ph.D., asserted at the San Antonio Breast Cancer Symposium.
Breast-conserving surgery (BCS) without radiotherapy constitutes a failure to provide adequate local tumor control.
Some prominent epidemiologists predict this will lead to increased late mortality, although that prediction is controversial.
Regardless, compelling evidence indicates this failure results in increased risk of local recurrences requiring additional, more aggressive surgery—often mastectomy—along with systemic chemotherapy.
Thus, the declining rate of radiotherapy serves to undermine the whole point of breast-conserving therapy: to provide outcomes equivalent to mastectomy, but with better quality of life, explained Dr. Virnig, who is with the University of Minnesota School of Public Health, Minneapolis.
“On a population basis, this trend is going to cause some real problems,” she added in an interview.
“It seems like in the end what we're doing is delaying treatment for these women until they'll end up needing more aggressive therapies that probably could have been avoided.”
She analyzed treatment trends in more than 175,000 women in the National Cancer Institute Surveillance, Epidemiology, and End Results registry who underwent treatment for nonmetastatic breast cancer during 1992–2003.
In 1992, the year after an NCI consensus panel declared BCS plus irradiation to be the preferred strategy over mastectomy in women with early-stage cancer, 41% of patients received BCS. That rate climbed to 60% by 2003.
Meanwhile, the use of radiotherapy following BCS dropped from 79% to 71% during the same period.
Among patients under age 55 who received BCS, the rate of radiotherapy fell from 81% in 1992 to 67% in 2003.
Radiotherapy use was also less frequent in women with estrogen receptor-negative tumors.
“We were particularly troubled that it was the younger women who had the steepest decline, and the ones with estrogen receptor-negative tumors, because they have the highest risk of recurrence and they don't have tamoxifen or the aromatase inhibitors as a protective net. These are women for whom there really isn't a preventive treatment available right now other than chemotherapy or irradiation,” Dr. Virnig observed.
The task now, she added, is to figure out why the decline in radiotherapy is occurring and how to address it.
It's unclear how much of the problem is caused by insurance issues, lack of convenient access, truly informed patient preference, or surgeon reluctance to refer to radiation oncologists.
Dr. Kenneth Smith, a Columbus, Ga., general surgeon, asserted that local recurrence rates are surely lower today with BCS alone with clear margins than in the 15- to 20-year-old studies on which the National Cancer Institute endorsement of BCS plus irradiation were based. He credited the decline to better imaging, improved pathology, and refinements in surgical technique.
Dr. Smith pointed out that a number of recent large single-center studies have reported no increase in local recurrences after BCS alone, at least in cases of ductal carcinoma in situ.
“The problem is that patients who go to those institutions—M.D. Anderson Cancer Center, University of Minnesota, Memorial Sloan-Kettering Cancer Center—those aren't your typical patients and they're not your typical doctors,” Dr. Virnig replied.
Dr. Smith conceded that it's not reasonable to extrapolate from the data accrued by highly experienced specialists to “the guy who does maybe five or six lumpectomies per year.”