Outcomes of Tamoxifen Treatment Alone in Patients With Ductal Carcinoma In Situ or Atypical Ductal Hyperplasia Who Refused Surgery

Objective: Recent trends involving increased screening have led to broad populations being diagnosed with atypical ductal hyperplasia (ADH) or ductal carcinoma in situ (DCIS); as a result, many patients have had to receive surgery followed by standard treatment for ADH or DCIS. The common interest in reducing the use of superfluous invasive treatment has led us to question the necessity of surgical treatment for ADH or DCIS patients in a retrospective review. This work is expected to be a particularly useful reference as there have yet to be any studies describing the outcomes of initial treatment with tamoxifen without curative surgery in Korea.Methods: The clinicopathological characteristics and oncologic outcomes of 36 patients with DCIS or ADH diagnosis who received initial treatment with tamoxifen between 2013 and 2019 were investigated.Results: Among 36 patients enrolled, 30 were diagnosed with DCIS and six were diagnosed with ADH. The median age in the included cohort was 47 years old (range, 26-81 years). There was a change in the follow-up strategy including the need for surgery in 13.9% of cases. The median time to surgery in those patients was 32 months (IQR, 17.5-63.5 months). Only one patient had upgraded to a higher nuclear grade, which was a case of ADH upgrading to intermediate DCIS. Three (8.3%) of 36 patients were upstaged to an invasive disease. Of them, two patients were upstaged to microinvasive ductal carcinoma, whereas one patient was diagnosed with metastatic invasive ductal carcinoma.Conclusion: The use of endocrine therapy without surgery could be a potential treatment strategy in patients with DCIS or ADH. Further validation in larger cohorts and in the context of clinical trials is needed.