Comparison of Outcomes for Classic-Type Lobular Carcinoma In Situ Managed with Surgical Excision After Core Biopsy Versus Observation.

BACKGROUND

Studies report low upgrade rates following excision for classic-type lobular carcinoma in situ (LCIS) with radiologic-pathologic concordance. Thus, in the absence of other high-risk lesions, observation has become standard. We report long-term outcomes of excision versus observation following a core biopsy diagnosis of classic-type LCIS.

METHODS

Women with LCIS treated from 2013-2020 and managed with excision or observation were identified from a prospective database. Women with cancer upgrade at excision or history of cancer were excluded. We compared rates and characteristics of subsequent breast cancers by clinical management strategy.

RESULTS

Of 312 women, 170 (54%) underwent excision and 142 (46%) were managed with observation. Among the excision group, 36 of 170 (21%) had radiologic-pathologic concordant LCIS without other high-risk lesions, mass, or symptoms (concordant LCIS excision group). Overall, at 3.1 years median follow-up, 11 (6.5%) women managed with excision and 11 (7.7%) women managed with observation developed cancer. Cancer development was not associated with management choice (overall excision cohort vs. observation group [p = 0.8]) and did not differ between the concordant LCIS excision and observation groups (p > 0.9). The 5-year cancer development rate was 8.9% (95% confidence interval [CI]: 2.3-31.6%) in the concordant LCIS excision group and 10.3% (95% CI 5.5-18.6%) in the observation group.

CONCLUSIONS

No difference in breast cancer rates existed among women with a core-biopsy diagnosis of classic-type LCIS managed with excision or observation. These data support management of LCIS as a risk factor, with consideration of chemoprophylaxis, rather than as an indication for surgical excision.