Ultrasound for Breast Cancer Detection in Low-Resource Settings: Systematic Review and Meta-Analysis

Purpose Of breast cancer–related deaths worldwide, 62.1% occur in low- and middle-income countries (LMICs). Mammography, the gold standard for screening, is largely infeasible in limited-resource settings, predominantly because of unavailability. Recent data show a dismal 0 to 12 mammography units per one million women age 50 to 69 years in most of sub-Saharan Africa. Breast ultrasound, which is used in high-resource settings to supplement mammography in certain clinical scenarios, offers a potentially viable alternative for early breast cancer detection in resource-limited areas because it is portable, economical, and a versatile technology. Methods We conducted a review of the literature to assess the potential for ultrasound alone in the detection of breast cancer. PubMed and Scopus queries with terms “breast neoplasms” and “diagnostic imaging” were systematically filtered to n = 33. Inclusion criteria were peer-reviewed studies in human participants, retrospective or prospective reviews, and a reference standard of biopsy/histopathology. Each paper was required to have extractable data with which to calculate true positives, false positives, true negatives, and false negatives. Breast imagers reviewed each paper using QUADAS and reached consensus for inclusion. Results Heterogeneity analyses confirmed a high diversity of all included studies. Pooled weighted analyses of all included studies demonstrated that the sensitivity of ultrasound for the detection of breast cancer ranged from 17% to 100%, with a 69% mean. This is higher than the known reported sensitivity of mammography for breast cancer detection of 67.8%. The specificity of ultrasound ranged from 28% to 100%, with a pooled total specificity of 97%, which is higher than the known specificity of mammography of 75%. In addition, ultrasound performed with superior sensitivity to mammography in the studies performed in LMICs that directly compared ultrasound with mammography (six of 11 studies). In the remaining five studies in LMICs, the sensitivity of ultrasound for breast cancer detection was high and ranged from 62% to 100%. Stratified analyses by age, breast density, presenting symptoms, and high-risk factors maintained the high sensitivities and specificities of ultrasound. Conclusion Sensitivities and specificities of ultrasound are comparable to mammography for the detection of invasive breast cancer. Handheld ultrasound may offer a viable alternative where mammography is not widely available as a primary detection modality for breast cancer. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to asco.org or ascopubs.org . Susan Harvey Honoraria: Hologic Inc, IBM Watson Imaging Consulting or Advisory Role: IBM Watson, Hologic Inc Research Funding: IBM Watson