Purpose: Although ductal carcinoma in situ (DCIS) seldom involves lymph nodes, some patients may upstage to invasive disease, thus requiring a second surgery for sentinel lymph node (SLN) biopsy (SLNB). However, the indications of SLNB remain inconclusive and clinical trials are rarely available. Our aim is to systematically review the real-world data to evaluate whether SLNB is precisely applied in patients with a high risk of upstaging from DCIS to invasive carcinoma. Methods: PubMed, EMBASE, and Cochrane library databases were searched. Prospective and retrospective cohort studies that evaluated the pathological outcomes of SLNB and the upstaging rate in women with DCIS were included. The primary outcomes were the upstaging and SLN-positive rates of patients initially diagnosed as having DCIS. We analyzed factors, namely biopsy methods, clinical presentations, histological patterns, and hormone receptor status, that potentially indicate nodal involvement risk. Results: We retrieved 43 prospective and 69 retrospective studies including 44,001 patients. The pooled estimates of upstaging and SLN-positive rates were 25.8% (95% confidence interval [CI]: 0.230–0.286) and 4.9% (95% CI: 0.042–0.055), respectively. In subgroup analysis, the upstaging rate was significantly higher in patients with estrogen receptor-negative status, palpable mass, tumor size >2 cm on imaging, and high-nuclear grade and those who received a preoperative diagnosis through core needle biopsy. Conclusion: The upstaging and SLN-positive rates of DCIS were 25.8% and 4.9%, respectively. By selecting patients with high risk DCIS, surgeons may increase the precision of and reduce the excess and incomplete treatment rates of SLNB.
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