Risk factors for lymph node metastases in breast ductal carcinoma in situ with minimal invasive component

Hypothesis: Clinical and pathological variables may be predictors of axillary dissemination in T1mic and T1a breast carcinoma. Design: Retrospective medical chart review. Setting: University-affiliated tertiary referral center. Patients: All patients diagnosed as having ductal carcinoma in situ (DCIS) with microinvasion between January 1, 1988, and December 30, 1998. Main Outcome Measures: Pathology slides were reviewed according to the 1997 Cancer Staging Manual put forth by the American Joint Committee on Cancer. The number of involved ducts was noted. Patients with no invasive component or invasive components larger than 5 mm were excluded. Pathological and clinical variables were analyzed for their effect on axillary lymph node metastases. Results: The study group included 57 women aged 37 to 71 years (median, 60 years), 37 with T1mic disease and 20 with T1a. Modified radical mastectomy was performed in 29 patients (18 with T1mic and 11 with T1a) and breast-preserving surgery in 28 (19 with T1mc and 9 with T1a). Forty-three patients (28 with T1mic and 15 with T1a) underwent axillary lymph node dissection. Axillary involvement was detected in 3 patients in each group. Forty-seven patients received adjuvant therapy (radiotherapy alone, or with hormones or chemotherapy). Follow-up was 3 to 120 months (median, 40 months). One patient was unavailable for follow-up, another died of disseminated disease, and a third developed contralateral primary carcinoma. Comedo DCIS (P<.03) and the number of DCIS-involved ducts (P<.002) in the T1mic group, and nuclear grade 3 (P<.001) in both groups, were independent significant predictors of axillary metastases. Conclusions: The significant rate of axillary metastases in T1a and T1mic breast tumors makes axillary staging a must. High nuclear grade, comedo DCIS, and high number of DCIS-involved ducts may predict axillary metastasis and should be considered when axillary dissection is done selectively.