Risk of Breast Cancer in Selected Women with Atypical Ductal Hyperplasia Who do not Undergo Surgical Excision

Objective: To review breast cancer incidence in women with ADH diagnosed by CNB and managed nonoperatively. Background: ADH found on CNB is associated with an upgrade to carcinoma in 10%-50% of women, thus surgical excision remains the standard of care. Safety of nonoperative management is unknown. Methods: ADH patients diagnosed between January 2004 and October 2018 were identified. Subsequent breast cancer events were compared between those who were excised and those who met predetermined criteria of low risk and were thus observed. Subsequent breast cancer events were classified as index site event if identified in the same quadrant as prior ADH. Multivariable logistic regression models were used to assess potential predictors of subsequent breast cancer events. Results: Four hundred seventy-eight women with 483 ADH lesions were identified; 309 were observed and 174 underwent excision. Median follow-up was 5.2 years. Prior breast cancer history was the only factor associated with subsequent breast cancer risk (odds ratio 2.25, 95% confidence interval 1.04-4.87). After excluding patients with a breast cancer history, there was no association of age, race, chemoprevention, or surgical excision of ADH with future cancer risk. 21/387 patients without a breast cancer history developed a subsequent cancer; 10 (7.3%) in the surgical group and 11 (4.4%) in the observed (P = 0.2). Two cancers were identified at the index site in the surgery group (2/137, 1.5%) and three in those observed (3/250, 1.2%). Conclusions: Observation, rather than surgical excision, is safe in select women with ADH. National guidelines should consider observation for this select group of patients.