Impact of mammography detection on the course of breast cancer in women aged 40-49 years.
Objective: To analyze trends in detection method related to breast cancer stage at diagnosis, treatments, and outcomes over time among 40-49-year-old women.
Methods: i This study was institutional review board approved, with a waiver of informed consent, and HIPAA compliant. A longitudinal prospective cohort study was conducted of women aged 40-49 years who had primary breast cancer, during 1990-2008, and were identified and tracked by a dedicated registry database (n = 1977). Method of detection--patient detected (PtD), physician detected (PhysD), or mammography detected (MamD)--was chart abstracted. Disease-specific survival and relapse-free survival statistics were calculated by using the Kaplan-Meier method for stage I-IV breast cancer.
Results: A significant increase in the percentage of MamD breast cancer over time (28%-58%) and a concurrent decline in patient and physician detected (Pt/PhysD) breast cancer (73%-42%) (Pearson x(2) = 72.72, P < .001) were observed over time from 1990 to 2008, with an overall increase in lower-stage disease detection and a decrease in higher-stage disease. MamD breast cancer patients were more likely to undergo lumpectomy (67% vs 48% of Pt/PhysD breast cancer patients) and less likely to undergo modified radical mastectomy (25% vs 47% of the Pt/PhysD breast cancer patients) (P < .001). Uncorrected for stage, 13% of MamD breast cancer patients underwent surgery and chemotherapy versus 22% of Pt/PhysD breast cancer patients (P < .001), and 31% of MamD breast cancer patients underwent surgery, radiation therapy, and chemotherapy versus 59% of Pt/PhysD breast cancer patients (x(2) = 305.13, P < .001). Analyzing invasive cancers only, 5-year relapse-free survival for MamD breast cancer patients was 92% versus 88% for Pt/PhysD patients (log-rank test, 12.47; P < .001).
Conclusions: Increased mammography-detected breast cancer over time coincided with lower-stage disease detection resulting in reduced treatment and lower rates of recurrence, adding factors to consider when evaluating the benefits of mammography screening of women aged 40-49 years.