PURPOSE: Breast-conserving surgery for larger ductal carcinoma in situ (DCIS) remains limited. We compare the attempted use and success rates of lumpectomy surgery in patients with DCIS measuring ≥ 4 cm versus <
4 cm. METHODS: A retrospective review was conducted using the institutional tumor registry to identify cases of pure DCIS that were surgically treated from 2015 to 2022. Clinical-pathological data were abstracted from electronic medical records. Pathologic tumor size on initial surgery was used to define the two cohorts. Comparisons of variables were made using Chi-square and ANOVA tests. RESULTS: A total of 669 patients, 84% (562) with tumors measuring <
4 cm and 16% (107) ≥ 4 cm were identified. Lumpectomy was the initial surgery performed for 89% of women with lesions measuring <
4 cm on preoperative imaging studies compared to 64% of those ≥ 4 cm. Overall, 461 (92.9%) of 496 in the <
4 cm succeeded at lumpectomy compared to 36 (56.3%) of 64 in the ≥ 4 cm group. Re-excision lumpectomies or mastectomy were performed in 27% and 44% of the <
4 cm and ≥ 4 cm subgroups. Lumpectomy was achieved for 70% of women with tumors in the 4 to 5.9 cm range compared to 33% in the 6-7.9 cm and the ≥ 8 cm groups. There were no local recurrences in the ≥ 4 cm group at an average of 4.4 years follow-up. CONCLUSION: Lumpectomy is a viable option for many patients with DCIS ≥ 4 cm, especially those measuring <
6 cm, though repeat re-excisions may be required after initial attempt.