As most patients receiving immunotherapy for head and neck cancer do not experience benefit, identifying clinical, laboratory or genomic markers to predict response is an important goal. Maximum standardized uptake (SUVmax) value on Positron Emission Tomography-Computed Tomography (PET-CT) has been reported as a potential clinical predictor for outcome. No studies have been reported to assess the potential relationship between SUVmax, genomic profile and outcome in head and neck cancer populations receiving immunotherapy.
We reviewed the data of 143 patients treated with immune checkpoint inhibitor (ICI) drugs for mucosal head and neck cancer. Patients who underwent PET-CT within 180 days of ICI start date were included for review. Patients were stratified to quartiles based on SUVmax to facilitate statistical analysis. Basic demographic data, smoking status, tumour mutational burden were analyzed. Overall survival and progression-free survival were assessed. Response to treatment was assessed using the RECIST criteria v1.1. Tumor mutational burden was assessed using our institutional next-generation sequencing targeted panel of 468 cancer-associated genes. Host factors, including pre-treatment peripheral blood data (neutrophil:lymphocyte ratio), were also assessed. Data analysis was performed using Stata v16.
Of 143 patients, 98 met inclusion criteria for analysis. Median age was 62.2 years (IQR 17.18). Overall 78.6% were male. Average recorded SUVmax was 12.14. Site for recorded SUVmax was head & neck in 48%, lung 30.6%, bone 11.2%, GIT/liver 10.2%. In patients with metastases, average number of metastatic sites was 1.9. In total, 19 patients were treated with ICI for recurrent rather than metastatic disease. The site of SUVmax was at a primary recurrence site rather than metastatic site in 31.6%. Average time from PET-CT to start of ICI was 52 days.
Higher SUVmax was associated with poorer overall survival under ICI therapy (HR 1.05, p= 0.030, 95% CI 1.004-1.093) (fig.1). No association was found between SUVmax and tumor mutational burden, tumor response to ICI or tumor progression. A statistically significant association between neutrophil:lymphocyte ratio and SUVmax was also observed (r = 0.32, p=0.0015) (fig. 2).
Higher SUV max was associated with higher neutrophil:lymphocyte ratio—a strong prognostic marker in head and neck cancer—and poorer overall survival among patients treated with ICI. SUVmax on PET-CT may provide clinically useful information when risk-stratifying patients receiving immune checkpoint inhibitors for head and neck cancer.