Mark A. Helvie, MD, from the University of Michigan Health System in Ann Arbor, and colleagues examined trends in late-stage cancer and invasive cancer incidence using data from the Surveillance, Epidemiology, and End Results program. They compared data from the premammography period (1977–1979) with the mammographic screening period (2007–2009) for women aged ≥40 years. Prescreening temporal trends were estimated based on annual percentage change (APC) values. Prescreening stage-specific incidence values were adjusted using differing APC values.
The researchers found that the prescreening APC temporal trend estimates varied from 0.8–2.3%. With an APC of 1.3% (which approximated the four-decade Connecticut Tumor Registry trend of 1.2%) there was a 37% decrease in late-stage breast cancer incidence (56 cases per 100,000 women), with a reciprocal increase noted in early-stage rates. At APCs of 0.5 and 2.0%, late-stage cancer incidence decreased by 21 and 48%, respectively. There was a 9% decrease (27 cases per 100,000 women) in total invasive breast cancer at an APC of 1.3%.
“There is evidence that a substantial reduction in late-stage breast cancer has occurred in the mammography era when appropriate adjustments are made for prescreening temporal trends,” the authors write.
Two authors disclosed financial ties to GE Healthcare.