Stage Migration and Dilution of Higher Stages With PET in Head and Neck Cancer in a Managed Care Setting
A study reported in JAMA Otolaryngology-Head & Neck Surgery by VanderWalde and colleagues suggests that increasing use of positron emission tomography (PET) for diagnosis and staging of head and neck cancer has resulted in considerable stage migration characterized by dilution of higher stages with patients who have better prognosis.
Study Details
In the study, 958 adult patients with head and neck cancer treated between 2000 and 2008 at four integrated health systems were identified through tumor registries linked to administrative data. American Joint Committee on Cancer (AJCC) stage distribution, patient and treatment characteristics, and survival in the pre-PET era (2000-2004) vs the PET era (2005-2008) and use of PET vs no use of PET during the PET era were compared. AJCC stages were categorized as localized (stage I or II), locally advanced (stage III, IVA, or IVB), or metastatic (stage IVC) disease. Treatments were determined by billing codes.
Pre-PET vs PET Era
In total, 46% of patients were treated in the PET era. There were no significant differences between the pre-PET and PET era in primary tumor site, stage, age, sex, or comorbidities. For the PET era vs the pre-PET era, there was less use of surgery (53.7% vs 66.9%, P < .001) and more use of chemotherapy (25.9% vs 20.5%, P = .05). There was no difference in 2-year overall survival (74.0% vs 75.5%, P = .34).
Differences With Use vs Nonuse of PET in PET Era
In the PET era, the imaging technique was used in 33.0% of patients and not used in 67.0%. Tumor site was significantly associated with use of PET for staging (P < .001). Younger patients and patients with later years of diagnosis were more likely to have undergone 18F–fluorodeoxyglucose (FDG) PET scans (P < .001).
Use of FDG-PET for staging increased from 12.5% of patients in 2005 to 34% in 2008. Compared with patients who did not undergo PET imaging, those who underwent PET were more likely to receive radiation treatment (83.3% vs 48.3%, P < .001) and chemotherapy (43.1% vs 17.5%, P < .001) and less likely to receive no treatment (0% vs 18.8%, P < .001).
Within the PET era cohort, patients who underwent imaging were significantly more likely to be staged as having locally advanced disease vs those not undergoing PET (62.5% vs 35.3%; 31.9% vs 62.0% staged as having localized disease; overall P < .001). Among patients with oral cavity and laryngeal or hypopharyngeal disease, most who underwent PET were staged as having locally advanced disease, whereas most who did not undergo PET were staged as having local disease. This disparity was not observed among patients with oropharyngeal or nasopharyngeal disease.
A logit model analysis showed that PET use vs nonuse was associated with a significantly higher risk of being staged with locally advanced disease (odds ratio [OR] = 2.86, P < .001). Other significant predictors of being assigned higher-stage disease included male sex (OR = 0.65, P = .005, for female vs male) and oropharyngeal disease (OR = 3.34, P <.001) and nasopharyngeal disease (OR = 2.20, P = .03) compared with oral cavity disease.
Survival Difference
In the PET era, there was no difference in 2-year overall survival in all patients undergoing vs not undergoing PET (53.2% vs 55.5%, P = .69). However, a significant increase in stage-specific survival was detected for PET vs no PET in patients with locally advanced disease (2-year overall survival = 32.1% vs 52.2%, P = .004).
No stage-specific survival differences were observed among patients with local disease or metastatic disease according to PET vs no PET. On multivariate analysis, there was no significant association between use of PET in locally advanced disease and overall survival (hazard ratio = 1.21, P = .40).
“The increasing use of PET among patients with [head and neck cancer] is associated with a greater number of patients with higher-stage disease and a dilution of the population with higher-stage disease with patients who have a better prognosis,” concluded the study authors. “Thus, the improved survival in patients with locally advanced disease likely reflects selection bias and stage migration. Further research on PET use among patients with [head and neck cancer] is necessary to determine if it results in improved treatment for individual patients.”
The study was funded by grants from the National Cancer Institute.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
