Increased risk of recurrence associated with certain risk factors in breast cancer patients after DIEP-flap reconstruction and lipofilling-a matched cohort study with 200 patients.

BACKGROUND: Lipofilling is performed in breast cancer patients to optimize the aesthetic outcome following breast reconstruction after mastectomy. Despite its common usage worldwide, little is known about the interaction of the lipoaspirate and dormant cancer cells. Up to date, no risk factors that increase the risk for cancer recurrence have been established. This study aims to identify risk factors for lipofilling candidates after breast cancer and questions the oncological safety of lipofilling in lymph node positive disease.

METHODS: Matched retrospective cohort study: the disease-free survival (DFS) between 100 breast cancer patients undergoing a lipofilling after their DIEP-flap reconstruction and 100 matched control patients with no subsequent lipofilling was analyzed. Further, patients were subdivided according to risk factors, which were categorized as patient-dependent factors (PDFs) and tumor-dependent factors (TDFs). DFS and hazard ratios (HR) were compared to identify potential risk factors that may increase cancer recurrence.

RESULTS: Median follow-up was 76.5 months from the mastectomy, and 31 months from the startpoint to the end of follow-up. Seven and eleven patients had recurrence in the lipofilling and control group, respectively, presenting with comparable DFS rates and an insignificant HR =0.57, 95% confidence interval (CI): 0.22-1.47, P=0.24. According to subgroup survival analysis, lipofilling increased the risk of recurrence in women with a positive nodal status (P=0.035) and a high-grade neoplasia (P=0.049).

CONCLUSIONS: No general increased recurrence risk was observed between the lipofilling and control group. The subgroup analysis identified high-grade neoplasia and positive nodal status to be a risk factor for cancer recurrence. Patients with a known node positive disease have an increased risk of occult micrometastases in their lymph nodes. Further studies are necessary to clarify whether dormant breast cancer cells in form of micrometastases in the lymph nodes can be reactivated by the factors secreted by adipose derived stem cells.