For patients with oropharyngeal squamous cell carcinoma (OPSCC), initial staging with PET is associated with better cancer-specific survival (CSS) than staging with other imaging modalities, based on a retrospective analysis of more than 1,700 patients.
PET was associated with a better 3-year overall survival rate than either MRI without PET or CT alone, reported lead author Rustain L. Morgan, MD, of the University of Colorado at Denver, Aurora, and colleagues.
“To our knowledge, there have been no prospective, randomized, controlled trials to date to evaluate the effect of different imaging modalities at the time of initial staging on cancer-specific survival,” the investigators wrote in Cancer. “A population-based data source such as the Surveillance, Epidemiology, and End Results [SEER]–Medicare database provides an excellent opportunity to compare the impact of imaging modality differences on survival in patients with OPSCC.”
Using SEER data, the investigators identified more than 3,704 patients with oropharyngeal cancer; following exclusions, 1,765 patients were involved in the final analysis based on various factors, including survival beyond 2 months after diagnosis and squamous cell carcinoma histology. A Cox proportional hazards model was used to assess relationships between the primary outcome and 3-year CSS rate and imaging, sex, age, region, race, and education.
Results showed that most patients had PET imaging upon diagnosis (83.3%), while fewer had CT alone (11.4%) or MRI without PET (5.2%). Several underlying trends were found: Patients in the West were more likely to undergo PET than patients in the Midwest, South, or East; patients younger than 75 years were more likely to have PET than older patients; and men were more likely to be staged with PET than women. The 3-year CSS was longest for patients who underwent PET (56.8%), followed by MRI without PET (50.1%) and CT alone (47.3%). Controlling for treatment and stage of disease, multivariate analysis also suggested that PET is associated with better CSS; patients staged with MRI without PET had a hazard ratio of 1.748 (P = .0036) and those imaged with CT alone had an HR of 1.337 (P = .0491). Although the Cox proportional hazards model for overall survival revealed numerical trends, these lacked statistical significance for MRI without PET (HR, 1.365; P =.0683) and CT alone (HR, 1.213; P = .114).
“The current study demonstrated a significant difference in CSS based on initial imaging,” the investigators wrote. “These findings are consistent with a prior study that reported that PET imaging can improve the staging of patients with head and neck cancers, particularly as it relates to radiotherapy planning.
“The data from the current study suggest the need for further prospective research to evaluate whether CT or MRI should be considered adequate for the initial staging of patients with OPSCC,” the investigators concluded.
The study was funded by the University of Colorado Cancer Center. One coauthor reported relationships with the American Heart Association and the National Heart, Lung, and Blood Institute.
SOURCE: Morgan RL et al. Cancer. 2019 May 1. doi:10.1002/cncr.32148.