Abstract P4-02-02: Outcomes of diagnostic surgical biopsy in a population-based mammographic screening program

Abstract

Abstract Background: Screening mammography allows earlier diagnosis of breast cancer resulting in reduced breast cancer specific mortality, and potentially reduced morbidity from less intense treatment. These benefits may be offset by investigation and treatment of lesions that are detected on screening but which are eventually found to be clearly benign, have uncertain malignant potential, or are malignant but pose no threat to the person during her natural life. Abnormalities detected on screening mammograms are recalled for further assessment. The outcomes of assessment may be confirmation of the absence suspicious findings. It may be a core biopsy is performed to clarify the nature of a persistently indeterminate or suspicious lesion. In cases when workup has neither diagnosed malignancy nor excluded its possibility, diagnostic surgical biopsy (DSB) is recommended. DSB of a lesion where final pathology is benign is a harm from a screening program. The benefit of DSB where a core needle biopsy (CNB) has shown a high-risk lesion is dependent on identifying more significant pathology than that of the CNB. Trials are currently recruiting which investigate a non-operative approach for DCIS, yet DSB is still standard of care for less significant/benign pathologies in much of the world. We aimed to determine the outcomes for patients recommended for DSB in a population-based mammographic screening program in order to identify situations in which this may safely be omitted. Methods: Ethics approval was obtained through Melbourne Health. Cases of DSB were reviewed from Northwest BreastScreen and Southern BreastScreen in Melbourne, Australia. Registry data was extracted including all patients where recommendation for DSB was made over a ten-year period (January 2004- December 2013). Patient demographics, imaging characteristics, core biopsy & surgical pathology were reviewed manually from individual BreastScreen files. Data points were entered to an Excell database. We reviewed assessment reports, tabulated indications for DSB, and surgical pathology reports for final histopathology. Results: 1286 patients underwent DSB over the ten-year period. The overall upgrade rate to malignancy on DSB after non-malignant finding on CNB was 21.6% (14% to DCIS and 7.6% to invasive cancer). Atypical ductal hyperplasia (ADH) was the most common pathology identified on CNB generating recommendation for DSB. The overall upgrade rate for ADH was 31%, including 5.5% to invasive cancer, and 25.5% to DCIS. Further analysis of these ADH upgrades to DCIS revealed majority to low grade DCIS. Discussion: A minority of patients with high-risk lesions, detected through screening mammography, were upgraded to malignancy on DSB in this cohort. The psychological and cost-effectiveness implications of this low upgrade rate to significant, life-threatening pathologies warrants further investigation. Future recommendations may involve including lesions of uncertain malignant potential or “high-risk” lesions in prospective observation and/or chemoprevention trials. This series suggests there may not be benefit in earlier diagnosis of the malignancies associated with ADH. Our data may therefore allow identification of groups of women who could be safely managed with less intensive treatment. Citation Format: Keane HJ, Elder K, Mann GB. Outcomes of diagnostic surgical biopsy in a population-based mammographic screening program [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-02-02.