Abstract P3-13-22: Should modified radical mastectomy be modified? A phase 1 study to evaluate infraradical mastectomy for invasive breast cancer

Abstract Background: Surgical procedures in breast cancer have become less aggressive. However, around one in three patients must undergo modified radical mastectomy (MRM). We evaluated if infraradical mastectomy (IFM), which preserves the skin and fat tissues surrounding the breast, is safe. IFM has the potential to preserve neck opening and by the way femininity of patients. Aesthetic results obtained after breast reconstruction are also expected to be improved. Objective: The primary objective of this phase 1 trial is to evaluate the feasibility and safety of IFM. Methods: Patients were recruited in two specialized breast clinics. We performed enucleation with a cold knife to the mammary gland after a water-assisted dissection of the periglandular space using a dedicated tool. In a second step we removed the peripheral skin and fat tissue which surrounded the gland to obtain a classical MRM. Fat tissue removed in the second step underwent a careful pathological examination (10 biopsies) in order to evaluate residual invasive or in situ breast cancer and atypical hyperplasia. We also evaluated which is the percentage of tissue and skin removed in the second step with regard to the global surgical specimen because that could be left in the future if the procedure is declared safe. Results: A total of 35 patients (43 to 80 years old) were prospectively recruited from March 2015 to March 2016. The distribution of tumor type was: pTis 2.9%, pT1 45.7%, pT2 45.7% and pT3 5.7%. Pathological analysis of the periglandular tissue removed in the second step revealed: 0% invasive carcinoma, 1% focal ductal carcinoma in situ (DCIS), and 0% atypical hyperplasia. On average, the weight of an IFM was 37% lower compared to the weight of a MRM. Skin resection was reduced by 48% with IFM. No serious adverse event was observed. Conclusions: Preliminary results are promising. Our phase 1 trial suggests that the procedure is safe concerning premalignant or malignant disease left after IFM. Moreover, a high quantity of skin and fat tissue is saved by IFM. We are now recruiting a second cohort of patients in order to confirm these results. In addition, we will also quantify the amount of mammary glands left around IFM compared to MRM by performing additional biopsies and quantitative evaluation by pathologists. Presurgical selection criteria have been modified for the second cohort in order to avoid residual DCIS left after IFM. After this second cohort, we plan to begin a large prospective randomized phase 3 trial with long-term disease-free survival and aesthetic results as the primary endpoints. Citation Format: Coibion M, Lifrange E, Jossa V, Mutijima E, Crevecoeur A, Olivier F, Di Bella J, Jerusalem G. Should modified radical mastectomy be modified? A phase 1 study to evaluate infraradical mastectomy for invasive breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-22.