Abstract P1-02-03: The effect on short–term progression free survival of the detection of ≥4 FDG-avid nodes or occult N3–disease in breast cancer patients with PET/CT

Abstract

Abstract Aim: The risk for locoregional recurrence (LRR), after neoadjuvant chemotherapy (NAC), is based on staging before NAC as well as the final pathology after NAC. Especially the number of tumour–positive axillary nodes, which is also an important selection factor for postoperative radiotherapy, is not adequately assessed by ultrasound before NAC or axillary lymph node dissection after NAC. PET/CT has a high positive predictive value for the detection of lymph node metastases. Newly found lymph node metastasis on PET/CT incentivized us to change the radiotherapy plan for patients with primary breast cancer scheduled for NAC in our institute. Koolen et al. reported an upstaging of 23% stage II–III breast cancer patients to the radiotherapy requiring high–risk group (≥4 FDG–avid axillary nodes or detection of occult N3–disease) due to new lymph node metastasis detected with FDG PET/CT imaging. In this study, we report the effect of this upstaging with PET/CT short–term progression free survival (PFS). Materials and methods: Between 2007 and 2011 a total of 278 breast cancer patients (mean age 48.9y, range 19–75y), with a tumour of at least 3 cm and without metastases, received a baseline PET/CT for staging purposes and subsequent response monitoring to NAC. The group was divided in three groups: a low– (T2N0), intermediate– (T0–2N1 and T3N0) and a high–risk group (T0–3N2–3, T3N1 and T4). We classified LRR, distant metastases and death as an "event"; including all patients in the PFS analysis of the first 3 years. Results: With a median follow–up (FU) of 37 months and the upstaging as depicted in table 1 Upstaging of breast cancer risk-group after PET/CTTotal group before PET/CTChanged After PET/CTComplete after PET/CT (FU-events)Low-risk: N=47N=5Low-risk (2) N= 42Intermediate-risk: N=144N=38Intermediate-risk N= 106 (14)High-risk: N=87xHigh-risk N= 130 (27)Total: N=278Total: N= 43Total N= 278Table 1: The group was divided in three groups: a low- (T2N0), intermediate- (T0-2N1 and T3N0) and a high-risk group (T0-3N2-3, T3N1 and T4). The table shows the upstaging of breast cancer patients from low- and intermediate- to the high-risk group, and thus, after PET/CT, requiring radiotherapy. : The patients not upstaged by PET/CT showed no difference in PFS between the high–risk, intermediate–risk and low–risk groups (Logrank p=0.18). Due to the migration of the 43 patients from the low– and intermediate group to the high–risk group, based on PET/CT findings, the PFS differed significantly between the risk–groups (Logrank p=0.04). No difference in loco–regional recurrence was seen between the low–risk and the high–risk group (P=0.18). Conclusion: After upstaging with PET/CT, into the high–risk group requiring radiotherapy, a significant difference is seen between the three risk–groups. PET/CT restaging may more adequately predict progression free survival. The detection occult lymphatic metastasis with PET/CT leads to upstaging in clinically unsuspected patients with primary breast cancer, enabling adequate radiotherapy treatment. Citation Format: Suzana C Teixeira, Bas B Koolen, Paula HM Elkhuizen, Vincent van der Noort, Marie-Jeanne Vrancken-Peeters, Marcel P Stokkel, Emiel J Th Rutgers, Renato A Valdés-Olmos. The effect on short–term progression free survival of the detection of ≥4 FDG-avid nodes or occult N3–disease in breast cancer patients with PET/CT [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-02-03.