Time to Diagnostic Resolution in Mobile Mammography Versus Urban Hospital-Based Breast Cancer Screening

Breast cancer screening via mobile mammography units (MMUs) can improve access in medically underserved communities. This study aims to evaluate factors associated with screening site, recall rates, and time to diagnostic resolution.

This retrospective study analyzed recall rates, time to diagnostic resolution, and sociodemographic factors in patients who underwent screening mammograms in an MMU versus urban hospital system during overlapping two-week periods in 2022 and 2023. For patients with BI-RADS 0 (incomplete) screening mammograms, our main analytic cohort, time intervals between screening and diagnostic imaging and, when indicated, between diagnostic imaging and biopsy, were measured. Diagnostic resolution was defined as time from screening to BI-RADS 1 (negative), 2 (benign), or 3 (probably benign) on diagnostic mammogram or, when indicated (BI-RADS 4 or 5 [suspicious or highly suspicious for malignancy, respectively]), from screening to biopsy. Chi-square, analysis of variance, and Kruskal-Wallis tests were performed to compare MMU- and hospital-screened women's characteristics. Cox regression analysis was used to assess factors associated with diagnostic resolution.

In the MMU cohort (n = 97) versus the hospital-based cohort (n = 236), more patients identified as Non-Hispanic Black (68% versus 40%), were uninsured (71% versus 2.1%), and had no primary care provider (35% versus 9.8%, all p<0.001). The MMU cohort also had a higher recall rate (18.8% versus 9.9%, p<0.001). Among BI-RADS 0 screening mammograms (n = 333), time to diagnostic resolution was longer among MMU- versus hospital-screened women (median 28 [IQR 15-51] vs 11 days [IQR 7-20], p<0.001). Patients with no insurance had a lower likelihood of diagnostic resolution (HR 0.42, 95% CI [0.26,0.69], p = 0.001). In the MMU cohort, 17/97 (18%) did not return for the recommended diagnostic imaging versus 9/236 (3.8%) in the hospital-screened cohort (p<0.001).

Although MMUs can improve access, our pilot study highlights opportunities to promote timely and equitable follow-up of abnormal screening mammograms through improved patient navigation, social-work support, and financial assistance.