ACR and SBI: Overdiagnosis and Survival Impact Claims of NEJM-published Study Are Unsupported
The data underlying a new study on breast cancer screening clearly show that mammography catches more cancers early and save lives by reducing the number of women with cancers of advanced size, according to the American College of Radiology and the Society of Breast Imaging.
ACR and SBI said the data do not support the conclusion of the study’s authors, Welch et al., that improved therapy is more key to breast cancer survival than mammography screening. Nor do the data support that mammography use leads to rampant overdiagnosis, ACR and SBI concluded.
The Welch et al. study was published Oct. 13 in the New England Journal of Medicine.
ACR and SBI said the numerical data in Welch et al. reinforce the position, supported by UCSF Imaging, that annual mammography screening beginning at age 40 can detect cancers before they reach advanced size. “Smaller cancers,” ACR and SBI said, “result in better outcomes for women. This not only helps save lives, but also allows more women to have their cancers treated with less extensive surgery, fewer mastectomies, and less frequent or aggressive chemotherapy. “
Dr. Bonnie Joe, MD, PhD, is chief of breast imaging at UCSF. She said, “The study’s authors make a fundamental flaw in their analysis by basing it on the assumption that breast cancer incidence is stable. Unfortunately, incidence has been increasing by 1 to 1.3% per year. The increase has been documented since the 1940s in the sameNational Cancer Institute Surveillance, Epidemiology and End Results (SEER) database used by Welch, et al.; however, they only used the years 1975-1979 to determine their baseline.” The ACR also pointed out that the baseline assumption on which the conclusions are based is contradicted by the primary author’s previous papers and research.
Dr. Joe continued, “When accounting for the increase in breast cancer incidence, there is little if any overdiagnosis of invasive breast cancers. In actuality, the rate of women presenting with large cancers and metastatic disease has dropped dramatically. Welch et al. do confirm the important point that tumor size at diagnosis matters—earlier detection allows treatment to be more effective. Mammography provides that early detection. And while it’s not perfect, data again show that mammography saves lives.”
For details on the ACR and SBI response to Welch et al., please see more here.