Women with Low-Risk DCIS Eligible for the LORIS Trial After Complete Surgical Excision: How Low Is Their Risk After Standard Therapy?

BACKGROUND: Identifying DCIS patients at low risk for disease progression could obviate need for standard therapy. The LORIS (surgery versus active monitoring for low-risk DCIS) trial is studying the safety of monitoring low-risk DCIS, although ipsilateral breast tumor recurrence (IBTR) rates in patients meeting enrollment criteria after complete surgical excision are unknown.
METHODS: Women with pure DCIS treated with breast-conserving surgery (BCS) with/without radiation therapy (RT) from 1/1996-1/2011 were included from a prospectively maintained database. IBTR rates were compared between those who did and did not meet LORIS eligibility criteria (age ≥ 46 years, screen-detected calcifications, nipple discharge absence, minimal family history, non-high-grade DCIS) after complete surgical excision.
RESULTS: A total of 2394 women were identified; 401 met LORIS criteria. Median follow-up was 5.9 years; 431 had ≥10 years follow-up. LORIS cohort median age was 61 years (range 46-86 years); 207 (52 %) underwent RT, 79 (20 %) received endocrine therapy. Of 401 patients, 24 experienced an IBTR. Overall 10-year IBTR rates were 10.3 % (LORIS) versus 15.4 % (non-LORIS) (p = 0.08); without RT, 12.1 versus 21.4 %, respectively (p = 0.06). The 10-year invasive-IBTR rates for women meeting LORIS criteria were: 5.3 % BCS overall, 6.0 % without RT.
CONCLUSIONS: Women meeting LORIS criteria (after complete surgical excision) are at somewhat lower risk for IBTR. Among such women undergoing excision without RT, the 10-year invasive-IBTR rate was 6 %. Given that approximately 20 % of women with core biopsy-proven non-high-grade DCIS have invasive cancer at excision, women managed without excision would be expected to incur higher invasive cancer rates. Additional criteria are needed to identify women not requiring intervention for DCIS.