Purpose: This study was designed to determine invasive cancer upstaging rates at surgical excision following vacuum-assisted biopsy of ductal carcinoma in situ (DCIS) among women meeting eligibility for active surveillance trials.
Methods: Patients with vacuum-assisted, biopsy-proven DCIS at a single center from 2008 to 2015 were retrospectively reviewed. Imaging and pathology reports were interrogated for the imaging appearance, tumor grade, hormone receptor status, and presence of comedonecrosis. Subsequent surgical reports were reviewed for upstaging to invasive disease. Cases were classified by eligibility criteria for the COMET, LORIS, and LORD DCIS active surveillance trials.
Results: Of 307 DCIS diagnoses, 15 (5%) were low, 95 (31%) intermediate, and 197 (64%) high nuclear grade. The overall upstage rate to invasive disease was 17% (53/307). Eighty-one patients were eligible for the COMET Trial, 74 for the LORIS trial, and 10 for the LORD Trial, although LORIS trial eligibility also included real-time, multiple central pathology review, including elements not routinely reported. The upstaging rates to invasive disease were 6% (5/81), 7% (5/74), and 10% (1/10) for the COMET, LORIS, and LORD trials, respectively. Among upstaged cancers (n = 5), four tumors were Stage IA invasive ductal carcinoma and one was Stage IIA invasive lobular carcinoma; all were node-negative.
Conclusions: DCIS upstaging rates in women eligible for active surveillance trials are low (6-10%), and in this series, all those with invasive disease were early-stage, node-negative. The careful patient selection for DCIS active surveillance trials has a low risk of missing occult invasive cancer and additional studies will determine clinical outcomes.