R1 resection margin after organ-sparing/oncoplastic surgeries for breast cancer

The recurrence rate after organ-sparing surgeries for breast cancer depends on the resection margins: R1 status is associated with a higher risk of recurrence than R0.
We analyzed a group of breast cancer patients with an R1 resection margin who underwent organ-sparing/oncoplastic surgeries. The R1 resection margin was detected in 62 out of 1279 patients who had organ-sparing/oncoplastic surgeries (4.9 % ± 0.6 %). In the group with invasive cancer and R1 resection margin, 80 % of patients were diagnosed with lobular carcinoma, whereas 14.8 % of patients had invasive cancer with no specific signs.
We divided the group of repeated surgeries according to their histological structure at the resection margin: 28 patients were found to have carcinoma in situ, while 13 patients had invasive cancer.
Among patients with carcinoma in situ, the resection margin after repeated surgery had no signs of malignancy in 14 women (50 %), while 10 (35.7 %) and 4 (14.3 %) women were diagnosed with carcinoma in situ and invasive cancer, respectively.
In case of invasive cancer, 4 patients (30.8 %) had no signs of malignancy in their resection margins, while 1 (7.7 %) and 8 (61.5 %) patients were found to have carcinoma in situ and invasive cancer, respectively
Follow-up of patients with an R1 resection margin after repeated surgery or radiotherapy revealed no cases of local recurrence between 3 and 65 months.