SABCS: As Breast-Conserving Surgery Increases, Radiation Therapy Lags Behind

Charles Bankhead,
SAN ANTONIO, Dec. 17 -- As breast-conserving surgery rates have increased, the use of adjuvant radiation therapy has not kept up, according to a study reported here. In fact, the proportion of patients receiving radiation therapy after breast conservation has decreased, with uncertain long-term consequences, Beth A. Virnig, Ph.D., of the University of Minnesota in Minneapolis, said at the San Antonio Breast Cancer Symposium.
Action Points --->
Explain to patients that this study found that fewer patients are receiving radiation therapy after breast-conserving surgery for early-stage breast cancer.
Note that an NIH consensus conference recommended radiation therapy for women who have breast-conserving surgery.
This study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary as they have not yet been reviewed and published in a peer-reviewed publication.
Using data from the Surveillance, Epidemiology, and End Results (SEER) cancer registry, Dr. Virnig and colleagues examined trends in surgical treatment of nonmetastatic breast cancer (stages 1-3) from 1992 through 2003. The analysis included women ages 18 to 79 at diagnosis and was limited to those with ductal or lobular histology.
During the period reviewed, 175,224 women were diagnosed with nonmetastatic disease. The proportion of patients undergoing breast-conserving surgery increased from 41% in 1992 to 60% in 2003, whereas the mastectomy rate decreased from 59% in 1992 to 40% in 2003 (P<0.0001). The increased use of breast-conserving surgery was apparent in all age groups, but was more common in younger patients and those with ER-positive tumors.
Over the same time period, use of radiation therapy after breast conservation decreased from 79% to 71% (P<0.0001). The steepest decline occurred in the youngest age group (18 to 54), for whom use of radiation therapy with breast-conserving surgery decreased from 81% in 1992 to 66.8% in 2003.
On a population-wide basis, the increase in breast-conserving surgery and the decline in accompanying radiation therapy resulted in a decrease in the rate of adequate local control (91% versus 82%, P<0.0001). Multivariate analysis showed that inadequate local control occurred more often in patients who were diagnosed in later years, younger patients, and patients with low-grade, ER-negative or smaller tumors.
"This trend in declining rates of adequate local treatment is not limited to patients with a low risk of recurrences after breast-conserving surgery," Dr. Virnig and colleagues concluded. "In fact, younger women and women with estrogen receptor-negative breast cancer were less likely to receive adequate therapy than their older or ER-positive counterparts."
"This is troubling because these groups have the highest risk of recurrence and may receive less protection from tamoxifen and aromatase inhibitors than older women and women with ER-positive tumors," they added.
The declining use of adjuvant radiation therapy clashes with the recommendations of an NIH Consensus Conference (JAMA 1991; 265: 391-395). The independent advisers to the NIH endorsed breast-conserving surgery for early-stage breast cancer because clinical trials showed that mastectomy and breast conservation plus adjuvant radiation therapy led to equivalent survival.
The success of a change in surgical practice from mastectomy to breast-conserving surgery hinges on patients' getting adjuvant radiation therapy after surgery, said Dr. Virnig.
"A failure to increase use of radiation therapy would result in a net decline in the percentage of women who received adequate local therapy for their breast cancer," she pointed out.
The study was supported by the University of Minnesota.
Dr. Virnig reported no disclosures.
Primary source: Breast Cancer Research and TreatmentSource reference:Virnig BA, et al "Increased use of breast-conserving surgery: preferred treatment or failure to provide adequate local therapy?" Breast Cancer Res Treat 2007; 106 (Supp1): Abstract 4065.