Neoadjuvant Endocrine Therapy and Delays in Surgery for Ductal Carcinoma in Situ: Implications for the Coronavirus Pandemic

BACKGROUND: Surgical delays are associated with invasive cancer for patients with ductal carcinoma in situ (DCIS). During the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pandemic, neoadjuvant endocrine therapy (NET) was used as a bridge until postponed surgeries resumed. This study sought to determine the impact of NET on the rate of invasive cancer for patients with a diagnosis of DCIS who have a surgical delay compared with those not treated with NET. METHODS: Using the National Cancer Database, the study identified women with hormone receptor-positive (HR+) DCIS. The presence of invasion on final pathology was evaluated after stratifying by receipt of NET and by intervals based on time from diagnosis to surgery (≤30, 31–60, 61–90, 91–120, or 121–365 days). RESULTS: Of 109,990 women identified with HR+ DCIS, 276 (0.3%) underwent NET. The mean duration of NET was 74.4 days. The overall unadjusted rate of invasive cancer was similar between those who received NET ((15.6%) and those who did not (12.3%) (p = 0.10). In the multivariable analysis, neither the use nor the duration of NET were independently associated with invasion, but the trend across time-to-surgery categories demonstrated a higher rate of upgrade to invasive cancer in the no-NET group (p < 0.001), but not in the NET group (p = 0.97). CONCLUSIONS: This analysis of a pre-COVID cohort showed evidence for a protective effect of NET in HR+ DCIS against the development of invasive cancer as the preoperative delay increased, although an appropriately powered prospective trial is needed for a definitive answer. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1245/s10434-021-10883-5.