Early 18F-FDG-PET Response During Radiation Therapy for HPV-Related Oropharyngeal Cancer May Predict Disease Recurrence

Int J Radiat Oncol Biol Phys. 2020 Nov 15;108(4):969-976. doi: 10.1016/j.ijrobp.2020.08.029. Epub 2020 Aug 13.

Abstract

Purpose: Early indication of treatment outcome may guide therapeutic de-escalation strategies in patients with human papillomavirus (HPV)-related oropharyngeal cancer (OPC). This study investigated the relationships between tumor volume and 18F-fluorodeoxyglucose positron emission tomography (PET) parameters before and during definitive radiation therapy with treatment outcomes.

Methods and materials: Patients undergoing definitive (chemo)radiation for HPV-related/p16-positive OPC were prospectively enrolled on an institutional review board-approved study. 18F-fluorodeoxyglucose PET/computed tomography scans were performed at simulation and after 2 weeks at a dose of ∼20 Gy. Tumor volume and standardized uptake value (SUV) characteristics were measured. SUV was normalized to blood pool uptake. Tumor volume and PET parameters associated with recurrence were identified through recursive partitioning (RPART). Recurrence-free survival (RFS) and overall survival (OS) curves between RPART-identified cohorts were estimated using the Kaplan-Meier method, and Cox models were used to estimate the hazard ratios (HRs).

Results: From 2012 to 2016, 62 patients with HPV-related OPC were enrolled. Median follow-up was 4.4 years. RPART identified patients with intratreatment SUVmax (normalized to blood pool SUVmean) <6.7 or SUVmax (normalized to blood pool SUVmean) ≥6.7 with intratreatment SUV40% ≥2.75 as less likely to recur. For identified subgroups, results of Cox models showed unadjusted HRs for RFS and OS (more likely to recur vs less likely) of 7.33 (90% confidence interval [CI], 2.97-18.12) and 6.09 (90% CI, 2.22-16.71), respectively, and adjusted HRs of 6.57 (90% CI, 2.53-17.05) and 5.61 (90% CI, 1.90-16.54) for RFS and OS, respectively.

Conclusions: PET parameters after 2 weeks of definitive radiation therapy for HPV-related OPC are associated with RFS and OS, thus potentially informing an adaptive treatment approach.

Trial registration: ClinicalTrials.gov NCT01908504.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Antineoplastic Agents / administration & dosage
  • Cisplatin / administration & dosage
  • Docetaxel / administration & dosage
  • Female
  • Fluorodeoxyglucose F18
  • Human papillomavirus 16
  • Humans
  • Kaplan-Meier Estimate
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local* / diagnostic imaging
  • Oropharyngeal Neoplasms / diagnostic imaging
  • Oropharyngeal Neoplasms / pathology
  • Oropharyngeal Neoplasms / radiotherapy*
  • Oropharyngeal Neoplasms / virology
  • Papillomavirus Infections / complications*
  • Positron Emission Tomography Computed Tomography / methods*
  • Proportional Hazards Models
  • Prospective Studies
  • Radiopharmaceuticals
  • Treatment Outcome
  • Tumor Burden

Substances

  • Antineoplastic Agents
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Docetaxel
  • Cisplatin

Associated data

  • ClinicalTrials.gov/NCT01908504