Comparison of mobile mammography versus urban hospital-based breast cancer screening.

1605 Background: Breast cancer screening via mobile mammography units (MMU) is used to improve access in medically underserved communities. This study aims to evaluate factors associated with site of screening, recall rates and time to diagnostic resolution for MMU vs hospital-based sites. Methods: This retrospective study analyzed screening mammography examinations performed in a MMU and at our large, urban hospital sites during overlapping 2-week periods in 2022 and 2023. BI-RADS, recall and cancer detection rates were assessed. For BI-RADS 0 patients, time intervals between screening and diagnostic imaging and, when indicated, between diagnostic imaging and biopsy, were collected. Area of Deprivation Index (ADI), an index of socioeconomic status for communities, was calculated for each patient. Diagnostic resolution was defined as time from screening to completion of diagnostic work-up. Statistical analyses were performed with chi-square, analysis of variance, and Kruskal-Wallis tests. Cox regression analysis was used to assess factors associated with diagnostic resolution. Results: In the MMU cohort (n=516) vs the hospital-based cohort (n=2401), more patients identified as Non-Hispanic Black (68% vs 40%, p < 0.001), reported no insurance (71% vs 2.1% p < 0.001), had no PCP (35% vs 9.8%, p < 0.001), and were in the highest ADI percentile (70% vs 27%, p < 0.001). Regardless of screening site, most patients with longer time to diagnostic resolution had a higher ADI percentile; 58% of patients with > 80 ADI percentile (p < 0.001) had diagnostic resolution in > 60 days. The MMU cohort had a higher recall rate (18.8% vs 9.9%; p < 0.001) and trend towards a higher cancer detection rate (13.6 vs 8.7 per 1000 examinations, p = 0.32) than the hospital-based cohort. Among BI-RADS 0 patients (n=333), there were longer delays to diagnostic resolution in the MMU vs the hospital-based cohort (Table 1). Patients with no insurance were less likely to have diagnostic resolution compared to insured patients (HR: 0.43, 95%CI [0.26,0.71], p = 0.001). Conclusions: Compared to hospital-based screening, MMU-screened patients experienced longer times to diagnostic resolution and had higher recall rates. Although MMU offers an effective strategy to improve screening access, our study highlights opportunities for improved patient navigation, social work support, and financial assistance to promote more equitable follow-up of abnormal screening mammograms. BI-RADS 0 outcomes. Facility Mobile Overall p-value N = 236 N = 97 N = 333 Median Days from Screening to Diagnostic (IQR) 11 (7, 20) 28 (13, 43) 13 (7, 28) <0.001 Median Days from Diagnostic to Biopsy (IQR) 12 (7, 18) 11 (6, 24) 12 (7, 19) 0.5 Median Days to Diagnostic Resolution (IQR) 14 (7, 29) 29 (16, 52) 17 (8, 34) <0.001 Days to Diagnostic Resolution <0.001 <=30 178 (75%) 42 (43%) 220 (66%) 30-60 33 (14%) 20 (21%) 53 (16%) 60+ 16 (6.8%) 17 (18%) 33 (9.9%) No Follow up 9 (3.8%) 18 (19%) 27 (8.1%)