Abnormal screens among nonmutation carriers in the High Risk Ontario Breast Screening Program

Abstract

Background:The Ontario Breast Screening Program was expanded in 2011 to offer annual MRI and mammography to women with high-risk genetic mutations (e.g., BRCA1/2) and women with strong family histories and ≥25% estimated lifetime risk of breast cancer. Data to support high-risk screening is less clear in the nonmutation carrier group, as MRI has lower specificity among this population. The potential unintended consequences may be considerable and need to be explored. We aimed to describe the frequency of abnormal screens and biopsies.Methods: Demographic surveys and chart review consent were sent to a sample of 441 individuals enrolled in a high-risk screening program at two tertiary care hospitals in Toronto, Ontario. Retrospective cross-sectional chart review was undertaken for clinicopathologic data. The frequencies of abnormal screens and biopsies were calculated.Results: One hundred sixty-nine nonmutation carriers were included. The majority were white, employed, and highly educated. The median International Breast Cancer Intervention Study lifetime risk of breast cancer was 28.0% (range 24.5%-89.0%). 108 individuals (64%) experienced at least 1 abnormal screen and 13 (8%) had 3 or more over a median 3 years of screening (range 1-6 years). Of 55 biopsies, 3 (5.5%) were malignant. The cancer detection rate was 8.4/1000 screens (95% CI 3.2-22.4).Conclusions: An MRI-based screening program for nonmutation carriers was effective at diagnosing breast cancer. However, this population experienced a high rate of abnormal screens and intervention. Further research is needed to improve the performance of MRI-based screening in these women.

Breast cancer screening: Helping patients navigate recommendations

“…The OBSP standard practice of annual mammography and breast MRI for screening high‐risk patients in this manuscript 1 mirrors recommendations by the ACS and closely aligns with those by the NCCN. The nonmutation carriers in the studied cohort required additional evaluation, biopsy, or follow‐up in 34% of patients per screening episode and nearly two‐thirds of women experienced at least one abnormal screen over the 3‐year course of the study.…”

“…The accompanying article by Castelo, et al 1 investigates the utility of high‐risk breast cancer screening in nonmutation carriers participating in the Ontario Breast Screening Program (OBSP) and examines their clinical experience over a 3‐year period. The authors noted that within their high‐risk patient population, nonmutation carriers (lifetime risk of breast cancer ≥25%) historically had a much lower cancer detection rate (9.4/1000 screens) compared with known mutation carriers (26.8/1000 screens).…”

“…In my experience, patients frequently misunderstand what average risk versus high‐risk means. Patients often focus on family history, linking it to potential increased risk associated with some genetic mutations, but high‐risk nonmutation carriers represent most of the high‐risk patient population (73% of the OBSP participants 1 ). Women with a lifetime breast cancer risk of 20%–25% are considered high‐risk, and the degree of risk can vary dramatically depending on the underlying cause.…”