Session Item

Tumor hypoxia is believed to be one of the contributors for treatment failure in non-small cell lung cancer (NSCLC), but has not been extensively evaluated as a prognostic/predictive factor in lung cancer. Hypoxia tracer 18F-Fluoroazomycin Arabinoside (¹⁸F-FAZA) provides a non-invasive method of hypoxia imaging. This prospective study aims to evaluate the feasibility and potential benefits of using FAZA-PET scans to assess NSCLC tumor hypoxia.

Patients diagnosed with stage II–III NSCLC have been recruited in this ongoing study, starting from January 2015. We report on the initial 27 patients.  All patients have been imaged with ¹⁸F-FAZA PET before initiation of curative radiotherapy, along with standard ¹⁸F-FDG PET for staging workup.  The maximum standard uptake value (SUVmax) of ¹⁸F-FAZA PET images, hypoxic volume (HV), Tumormax/Bloodmean  (T/B) ratio and hypoxic fraction (HF) were described for primary and nodal tumors.  Recurrence free survival (RFS) and overall survival (OS) were calculated from radiotherapy completion date to any recurrence (local/regional/ distant) and date of death from any cause, respectively. Spearman correlation and kappa coefficient were used to explore potential correlation and agreement among several variables such as: primary and nodal tumor volume, ¹⁸F-FAZA/hypoxia and ¹⁸F-FDG parameters, and clinical outcomes.

Intra-lesional hypoxia were identified in 21/27 (78%) patients for primary tumor volume, 14/27 (52%) patients for nodal tumor volume, and 22/27 (81%) patients overall.

Larger primary tumor volume is correlated with higher T/B (p=0.01) and higher HF (p=0.01). Primary tumors with higher T/B ratio also had higher HF (p<0.0001).  The same correlations also apply to nodal disease.  Nodal FAZA SUVmax correlated with primary FAZA SUVmax (p<0.0001).  After a median follow up of 21 months, RFS and OS at 2 years is 57% and 61%, respectively. Higher nodal volume is significantly associated with poorer overall and recurrence free survival, and time to distant recurrence.

Intra-lesional hypoxia in NSCLC primary and nodal tumors can be detected by ¹⁸F-FAZA PET. Initial results are encouraging. Ongoing trial accrual and long term follow-up of our patient cohort will provide more information with regards to the imaging and clinical value of ¹⁸F-FAZA PET. This study may eventually lead to using ¹⁸F-FAZA PET as a guiding tool to escalate dose to the hypoxic region of lung tumors.