Long-Term Safety of Observation in Selected Women Following Core Biopsy Diagnosis of Atypical Ductal Hyperplasia

Purpose: Atypical ductal hyperplasia (ADH) found on core biopsy is associated with an upgrade to carcinoma in 10–30 % of women, thus surgical excision remains the standard of care. This study compares the incidence of breast cancer in women with ADH who were observed with those who underwent surgical excision of the ADH site. Methods: Our departmental, prospectively maintained registry was reviewed to identify patients with ADH diagnosed by core biopsy. Surgically treated patients were excluded if upstaged to carcinoma following excision for ADH diagnosis. Breast cancer events were classified as index site (site of ADH biopsy), ipsilateral breast unrelated to index site, or contralateral breast. Results: Overall, 175 women met the study criteria; 125 were observed and 50 underwent excision. With a median follow-up of 3 years, 14 breast cancer events were noted in 13 patients. In the surgery group, six women developed breast cancer (12 %), including one bilateral, compared with seven cancers (5.6 %) in the observed group (p = 0.14). Index site events and ipsilateral cancers were the same in both groups [2 vs. 0.8 % (p = 0.49) and 4 versus 4.8 % (p = 1.00), respectively]. All contralateral cancers occurred in the surgical group (8 vs. 0 %; p < 0.01). A prior history of breast cancer was the only variable associated with subsequent breast cancer events (hazard ratio 12.53, 95 % confidence interval 3.30–47.57). Conclusion: Observation is appropriate in selected women with ADH on core biopsy. Index site failures are rare and are superseded by cancer risk elsewhere in the breast.