Abstract PO1-07-09: Benefit of Adherence to Annual Mammography Screening: Results from 8,305 Cancers in an Institutional Database
Authors: Nishikawa Robert , Bandos Andriy , Duffy Stephen , Logue Durwin , Zuley Margarita 
Published: May 2024

Purpose: There is much debate on the starting age and frequency for asymptomatic mammographic breast cancer screening. We analyzed data from our medical center to determine the effect of the frequency of screening on the likelihood of a woman being diagnosed with a late-stage cancer and on the all-cause mortality. Method: For this study, we used our institutional breast cancer care data mart, which contains data for all patients who had breast imaging or were treated for breast cancer at a University of Pittsburgh Medical Center (UPMC) facility between 2004 and 2019 inclusive. Including only women 40 years and older, 8,145 had at least one screening mammogram prior to their diagnosis of breast cancer. Screening exams less than 260 days apart were considered to be from the same screening episode. For the 8,145 women, we determined the interval between their two most recent screening mammograms and grouped them into: (i) Baseline (only 1 prior screening episode prior to diagnosis); (ii) Compliant (less than or equal to 15 months between the two most recent screening episodes); (iii) Delayed (more than 15 months but less than 27 months between the two most recent screening episodes); and (iv) Missed (more than 27 months between the two most recent screening episodes. Late-stage cancer was defined as TNM stage 2b or worst. In cancers arising in those with at least two prior screening examinations, we estimated and tested significance of effects of adherence category on risk of late-stage cancer using logistic regression. We estimated the corresponding effects on survival to death from any cause using proportional hazards model. The effect of compliance was evaluated univariately followed by the multivariable analysis accounting for demographic and clinical characteristics including age, race, and menopausal status. Analysis within practically relevant subgroups was performed for additional illustration. Results: For all-cause death 5-year mortality rate post-diagnosis was 4.2% for the Compliant group (n=3369, median follow-up 5.13 years), 5.9% for the Delayed group (n=1340, median follow-up 4.64 years), and 12.2% for the Missed group (n=1129, median follow-up 3.36 years). The overall 5-year mortality rate was 6.1% (n=8145, median follow 5.12 years). Both unadjusted and adjusted for age, menopausal status, and ethnicity, the poorer survival with lesser compliance was highly significant (with the adjusted hazard ratios relative to the baseline group of 0.5, 0.8, and 1.3 for the three compliance groups respectively, p&lt; 0.001). In the population overall, there was a significant trend of increasing risk of stage 2B or worse with lesser adherence to annual screening, the proportions being 9%, 14%, and 19% for the compliant, delayed, and missed groups respectively (p&lt; 0.001). This remained significant when adjusted for age, menopausal status, or ethnicity (p&lt; 0.001). The trend was significant within major demographic subgroups, except for a relatively small subpopulation of women with unknown menopausal status. Conclusions: Annual mammographic screening resulted in lower all-cause mortality and lower risk of late-stage cancers, for both white and black women and pre- and post-menopausal women. Our study clearly shows a benefit to screening all women over the age of 40 annually over longer periods between screens.

Table of Late-Stage Cancers by Screening Adherence and Demographic Factors

Diagnosis of breast cancer at stage 2B or higher by screening adherence group and demographic factors

Citation Format: Robert Nishikawa, Andriy Bandos, Stephen Duffy, Durwin Logue, Margarita Zuley. Benefit of Adherence to Annual Mammography Screening: Results from 8,305 Cancers in an Institutional Database [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-07-09.