Introduction/Background To evaluate the results of BCS for patients with DCIS.

Methodology We retrospectively analyzed the results of 172 patients diagnosed by vacuum assisted biopsy (VAB) or fine-needle aspiration biopsy (FNAB) of DCIS, between 2011 and 2017. We consider free margin ≤2 mm. Data was obtained with STATA14.

Results BCS was performed in 98/172 (57%) patients. In 83.7% of the patients, the diagnosis corresponds to a mammographic finding, whereas, 16.3% had a palpable lesion.

The mean age was 59.2 years (SD±11.3). After surgery, anatomopathological result showed: 66.3% (65/98) of DCIS, 24.5% (24/98) of infiltrating ductal carcinoma (IDC). 5 benign cases and 4 without residual tumor were found. Therefore, an underestimation in the diagnosis is observed in almost 25% of the cases.

72% had free margins (67/93), 11.8%(11/93)free but <2 mm, 12.9% (12/93) showed positive margins and 5.4% (5/93)focally affected.

19 re-excisions were carried out, obtaining a re-excision rate of 20%. The result was negative for 78.9%(15/19) of them and DCIS was found in the remained 4 cases.

Regarding lymph node involvement, Sentinel Lymph node biopsy (SLNB) was performed in 43/98 patients, of which one was positive presenting micrometastasis.

91 patients received adjuvant radiotherapy. Hormone therapy, Tamoxifen or Letrozole, was also given to 77 patients.

According to the last check, 81.6% (80/98) of the patients are free of recurrence. The remaining 18.4% (18/98) still have a follow-up <1year.

Conclusion Re-excision must be individualized according to: life expectancy, DCIS extension, margin’ proximity, residual calcifications or cosmetic impact, given the good long-term rates of local control compare to the consequences: increase in surgical complications, stress, cosmetic compromise or greater risk of mastectomy.

We must become more aware of the possible overtreatment of entities with a good prognosis, such as the DCIS, without forgetting the importance of a precise pre-surgical diagnosis.

Disclosure Nothing to disclose.