PET-CT surveillance post radiotherapy in advanced head and neck squamous cell cancer (HNSCC) – real life application of the PET-Neck protocol
Session type: Poster / e-Poster / Silent Theatre session
The PET-NECK study demonstrated surveillance CT-PET scan 12 weeks post-radiotherapy for HNSCC was non-inferior to planned neck dissection (ND). We evaluated this practice in our centre.
Patients with node positive HNSCC treated with radiotherapy between January 2013 and September 2016 were identified from the PET-CT database. CT-PET responses were classified retrospectively as complete (CR), incomplete (ICR) or equivocal (EQR) by a radiologist. Patient demographics and clinical outcomes were obtained from electronic patient records.
187 patients with HNSCC were identified, 74.8% male, mean age 59 years. 8%(15/187) with N2a, 57%(107/187) with N2b, 16%(29/187)with N2c, and 5%(9/187)with N3 disease. 80.2% received chemoradiotherapy. 81%(154/187) of patients had oropharyngeal cancer, 80.5%(124/154) were HPV-positive. Median follow-up was 30 months (IQR 21.6-39.7). Median time from end of radiotherapy to PET scan was 90days.
59.4%(111/187) had CR, 17.6%(33/187) ICR, and 23%(43/187) EQR nodal response. 21(11%) NDs were performed, 57.1% were pathologically positive. 1-year recurrence was 9.3%, 29.4% and 7.7% for CR, ICR and EQR groups respectively (p=0.04). 2 year survival was 91.9%, 50.0% and 87.5% respectively (p<0.001). No statistical differences in recurrence and survival rates between CRs and EQR at 1-year and 2-years. Only 10 NDs were carried out for the EQR subset with 50% pathological involvement. 20 patients with EQR underwent a repeat PET resulting in a further 12 CRs, suggesting the comparable outcomes between EQRs and CRs are not due to salvage ND and more likely to be related to slowly responding disease.
Overall locoregional control at 2 years was 94.8%(95% CI, 89.6-97.9) and 2 years survival was 83.5%(95% CI, 76.6-88.3).
Real life application of the PET-NECK protocol has resulted in similar outcomes to that seen in the study. Most patients are spared ND and disease control is maintained with PET-CT surveillance post-radiotherapy.