Oncologic safety of autologous fat grafting in primary breast reconstruction after mastectomy for cancer.

INTRODUCTION: Autologous fat transfer (AFT) is widely used to improve results of breast reconstructive surgery, but its safety is controversial. Our objective was to evaluate the oncologic safety of AFT in a homogeneous population of patients who underwent a total mastectomy with immediate reconstruction for breast cancer. METHODS: We performed a retrospective cohort study by identifying all patients who underwent immediate breast reconstruction after mastectomy for breast cancer from 2007 to 2015 in our center. A patient group with AFT performed in the 24 months after mastectomy was compared to a control group. RESULTS: Five hundred fifty cases were included, of whom 136 (24.7%) underwent at least one fat graft transfer. Median age was 51 years. Reconstruction was performed in 465 (84.5%) with an implant reconstruction. The median time from mastectomy to AFT was 13.8 months. The median follow up was 55.2 months. A total of 53 events were observed, including 10 (7.4%) in the AFT group and 43 (10.4%) in the control group. There was no difference in 5-year recurrence-free survival (RFS) between the groups. In the subgroup analysis, only lymph node involvement in patients who underwent AFT in the first 24 months after oncologic surgery appeared as a risk factor of recurrence. Among the 104 patients with lymph node involvement, 5-year RFS was 69.2% in patients with lipofilling vs 92.5% in patients without it (p = 0 0.0351). CONCLUSION: Performing early lipofilling in primary breast reconstruction after mastectomy for cancer seems to be oncologically safe. Lymph node involvement increases the risk of recurrence in this population.

Insertion of synthetic lesions on patient data: a method for evaluating clinical performance differences between PET systems.

BACKGROUND: Performance assessment of positron emission tomography (PET) scanners is crucial to guide clinical practice with efficiency. We have already introduced and experimentally evaluated a simulation method allowing the creation of a controlled ground truth for system performance assessment. In the current study, the goal was to validate the method using patient data and demonstrate its relevance to assess PET performances accuracy in clinical conditions. METHODS: Twenty-four patients were recruited and sorted into two groups according to their body mass index (BMI). They were administered with a single dose of 2 MBq/kg 18F-FDG and scanned using clinical protocols consecutively on two PET systems: the Discovery-IQ (DIQ) and the Discovery-MI (DMI). For each BMI group, sixty synthetic lesions were dispatched in three subgroups and inserted at relevant anatomical locations. Insertion of synthetic lesions (ISL) was performed at the same location into the two consecutive exams. Two nuclear medicine physicians evaluated individually and blindly the images by qualitatively and semi-quantitatively reporting each detected lesion and agreed on a consensus. We assessed the inter-system detection rates of synthetic lesions and compared it to an initial estimate of at least 1.7 more targets detected on the DMI and the detection rates of natural lesions. We determined the inter-reader variability, evaluated according to the inter-observer agreement (IOA). Adequate inter-reader variability was found for IOA above 80%. Differences in standardized uptake value (SUV) metrics were also studied. RESULTS: In the BMI ≤ 25 group, the relative true positive rate (RTPR) for synthetic and natural lesions was 1.79 and 1.83, respectively. In the BMI > 25 group, the RTPR for synthetic and natural lesions was 2.03 and 2.27, respectively. For each BMI group, the detection rate using ISL was consistent to our estimate and with the detection rate measured on natural lesions. IOA above 80% was verified for any scenario. SUV metrics showed a good agreement between synthetic and natural lesions. CONCLUSIONS: ISL proved relevant to evaluate performance differences between PET scanners. Using these synthetically modified clinical images, we can produce a controlled ground truth in a realistic anatomical model and exploit the potential of PET scanner for clinical purposes.