Volume-based parameters on FDG-PET/CT as early predictors of disease recurrence in postmastectomy breast cancer patients with one to three positive axillary lymph nodes without adjuvant radiotherapy.

Abstract

1124 Background: The indication for postmastectomy radiotherapy (PMRT) in patients with 1-3 lymph node metastases in the axilla have been controversial, despite the recommendation that PMRT should be applied. In the current study, we focused our study on volume-based parameters of pretreatment FDG-PET/CT, with the aim of investigating a measurement that could help identify high-risk populations for recurrence. Methods: We retrospectively analyzed 88 patients of breast cancer treated with modified radical mastectomy and were found to have 1-3 metastatic axillary lymph nodes between 2006 and 2010. All of them were studied with FDG-PET/CT for initial staging. We evaluated the relationship between clinicopathologic factors or PET parameters including the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and recurrence. MTV and TLG of the primary tumor and metastatic lymph node were measured by using semi-automatically delineated volume of interest (VOI) with an isocontour threshold of 40 % of the SUVmax. The optimal cutoffs of PET parameters were determined by ROC curve analysis. Results: The median follow up duration was 39 months. Median MTV was 21.1and median TLG was 42.7. Recurrence was observed in 10 patients. The area under the ROC curve of MTV and TLG for DFS was 0.82 and 0.85, respectively. In Cox univariate analysis, estrogen receptor status (HR = 6.8, p = 0.003), triple negativity (HR = 10.4, p = 0.0008), SUVmax (HR = 71.1, p = 0.001), MTV (HR = 130.3, p < 0.0001), and TLG (HR = 234.1, p = 0.0001) were significantly related to disease free survival (DFS). The estimated 3-year DFS rates were 96.4 % for the lower MTV group (< 31.8) and 71.4% for the higher MTV group (≥ 31.8, p = 0.0005). The estimated 3-year DFS rates were 95.8 % for the lower TLG group (< 109.6) and 50.0 % for the higher TLG group (≥ 109.6, p < 0.0001). On multivariate analysis, TLG was an independent prognostic factor of DFS (HR = 8.5, p = 0.005). Conclusions: Volume-based parameters on FDG-PET/CT were significant predictors of DFS in postmastectomy breast cancer patients with 1-3 metastatic axillary lymph nodes.