Purpose: There is uncertainty about the benefits of screening mammography in women 75 years and older, despite 18% of breast cancer cases in the United States (U.S.) occurring in this age group. Current US Preventive Services Task-Force (USPSTF) guidelines recommend routine screening for women aged 50 to 74, and large randomized trials haven't specifically addressed the benefits of screening mammography for the older population. This exclusion doesn't reflect the shifting demographics in the U.S. We aim to compare digital breast tomosynthesis (DBT) performance metrics in women aged 70-74 years, and women aged 75 and older. We also assess the impact of routine screening mammograms on survival.
Materials and Methods: We retrospectively reviewed 52796 consecutive screening mammograms from January-2015 to January-2020 and followed patient outcomes until August-2023. Screening metrics included rates per 1000 screens for recalls, biopsies, and cancers detected. The clinicopathological characteristics of patients were compared by chi-square test or Fisher's-exact test. Breast cancer-free survival was calculated by Kaplan-Meier survival analysis followed by Cox Proportional-Hazards-model for multivariate analysis. We also correlated annual or biannual screening mammograms with survival outcomes.
Results: Out of 52796 screening mammograms, 26436 patients aged 70-74 years and 26360 aged 75 years and older were included. 5387 patients were recalled, resulting in 1324 biopsy recommendations (24.58%). 1284 pathology reports were available, yielding malignancy in 453 patients, of which 397 had follow-up available and were included in the study (Table 1). Comparing the two age groups, patients aged 70-74 had a significantly higher abnormal interpretation rate (p=0.001). There was no difference in PPV-3 (p=0.394) and cancer-detection rate (p=0.393) between the two groups (Table 2). Patients aged 75 and older had a significantly higher rate of invasive disease at diagnosis (p=0.027) and worse prognostic staging (p=0.042). Cancer-free survival rate was significantly higher in patients aged 70-74 (82.2% vs. 73.5%; p=0.025). Furthermore, patients with DCIS (p=0.001), those undergoing surgery (p=0.005), and those with prior radiation (p=0.009) had better cancer-free survival (Figure 1). Moreover, age at diagnosis, previous chemotherapy and routine screening mammogram were independent prognostic factors for cancer-free survival in the entire cohort.
Conclusion: DBT screening maintains consistent performance for women aged 70-74 compared to those aged 75 and older. The positive impact of regular screening mammograms on better prognostic staging at diagnosis and enhancing cancer-free survival strongly supports continuing routine DBT screening for older women.
Clinical Relevance Statement: This study reinforces the significance of early detection and personalized care in advancing breast health outcomes for our aging population.
