Role of axillary staging in women diagnosed with ductal carcinoma in situ with microinvasion.

BACKGROUND

Axillary staging via sentinel node biopsy (SLNB) in patients with ductal carcinoma in situ with microinvasion (DCISM) is routinely performed but remains controversial with regard to the risk-benefit ratio.

METHODS

Retrospective single-institution review of patients with diagnosis of DCISM (invasive tumor ≤ 0.1 cm). Age, clinicopathologic data, and follow-up were recorded.

RESULTS

Of 90 patients, 33% were diagnosed by core needle biopsy (CNB), 37% by excisional biopsy, and 29% were upstaged from DCIS on CNB to DCISM at final operation. Three (10%) of 30 patients with DCISM on CNB were upstaged to invasive cancer on final pathology. Median age at diagnosis was 58.9 years (range: 30-89). Lumpectomy was performed in 45% of patients and mastectomy in 55%. Mean number of sentinel nodes was 2.59 (SE 0.17). Six (6.9%) of 87 patients with DCISM as final diagnosis had a positive SLNB (four lumpectomies, two mastectomies). There was no correlation with any clinicopathologic features, including palpable DCIS, DCIS grade/necrosis, or age at diagnosis. All six SLNB-positive patients had a complete axillary dissection; two had additional disease. Median follow-up time was 74.2 months (range: 2-169). In-breast recurrence was seen in three patients (5%), regardless of SLN status, DCIS grade, or necrosis. Two patients developed distant metastasis. Overall survival was 94.19% at 5 years for DCISM and 100% for DCISM with nodal disease.

CONCLUSION

DCISM comprises 0.6% of breast cancer diagnoses at our institution. There is a low likelihood of nodal spread; however, a lack of identifiable clinicopathologic features associated with a positive SLNB limits selective SLNB use.