BACKGROUND: The status of the surgical margins of lumpectomy is one of the most important determinants of local recurrence in breast cancer. Systematically practicing cavity margin resection is debated but may avoid surgical re-excision and allow the diagnosis of multifocality.
METHODS: This multicentric retrospective study included 294 patients who underwent conservative management of breast cancer with 2-4 systematic cavity shavings. Clinico-biological characteristics of the patients were collected in order to establish whether surgical management was modified by systematic cavity shaving. Local recurrence rate with a long-term follow up of minimum 4 years was evaluated.
RESULTS: Cavity shaving avoided the need for re-excision in 25% of cases and helped in the diagnosis of multifocality in 8% of cases. Resection volume was not associated with usefulness of the cavity shaving. No predictive factor of positive cavity shaving was found. The rate of local recurrence was 3.7% and appeared in a median time of 3 years and 8 month. Only one quarter of the patients with local recurrence had initially positive lumpectomy margins but negative cavity shaving.
DISCUSSION: Systematic cavity shaving can change surgical management of conservative treatment. No specific target population for useful cavity shaving was found, such that we recommend utilising it systematically.