Among patients with locally advanced head and neck squamous cell carcinoma who are ineligible to receive cisplatin, carboplatin-based chemoradiotherapy (CRT) may be a better option than cetuximab-based chemoradiotherapy, according to a new cohort study of U.S. veterans.
Although cisplatin is the favored treatment choice for these patients, kidney dysfunction, hearing loss, neuropathy, advanced age, and performance status can be contraindications. As radiosensitizing agents, both cetuximab and carboplatin-fluorouracil combined with radiotherapy have increased survival compared to radiotherapy alone in randomized, controlled trials.
, but no prospective trials have compared cetuximab and carboplatin-based radiosensitization, according to the authors of the new report, published online in JAMA Otolaryngology – Head & Neck Surgery.
Some small retrospective studies, generally performed at one or two institutions, found that carboplatin outperformed cetuximab with respect to progression-free and overall survival, but these were subject to natural biases as well as imbalances between the two treatment groups.
To address this literature gap, the authors conducted a nationwide retrospective analysis of 8,290 U.S. veterans, who have a high rate of frailty and comorbidities such as heart disease and tobacco use that could make them ineligible for treatment with cisplatin. Among the veterans, 5,566 were treated with cisplatin, 1,231 with carboplatin, and 1,493 with cetuximab. The overall median age was 63 years, 98.9% were male, 82.6% were White, 15.8% were Black or African American, 68.5% were current smokers, 13.0% were former smokers, and 18.5% had never smoked.
Patients treated with carboplatin and cetuximab were older and had more comorbidities than those treated with cisplatin. Sixty-five percent of patients treated with carboplatin also received paclitaxel. Fifty-eight percent had a primary oropharynx cancer.
Median overall survival was 59.3 months among all patients (interquartile range [IQR, 18.5-140.9 months]. Median OS was 74.4 months in the cisplatin group (IQR, 22.3-162.2), 43.4 months in the carboplatin group (IQR, 15.3-123.8), and 31.1 months in the cetuximab group (IQR, 12.4-87.8). There was a lower inverse probability weighted cause-specific hazard ratio (csHR) of death associated with carboplatin (csHR, 0.85; 95% confidence interval [CI], 0.78-0.93). The researchers compared survival associations in oropharynx and nonoropharynx subgroups and found a significant association in the oropharynx group (csHR, 0.82; 95% CI, 0.72-0.94) but only a trend in the nonoropharynx group (csHR, 0.88; 95% CI, 0.78-1.00).
Given that most oropharynx cancers are likely related to HPV, the authors speculate that the finding of an association in the oropharynx group but not the nonoropharynx group may be attributable to differences in treatment efficacy due to HPV status, since there is evidence beginning to mount that cetuximab may have lower efficacy in these cancers. “For patients who are ineligible for treatment with cisplatin, carboplatin-based radiosensitization may provide better oncologic outcomes than cetuximab, particularly for oropharynx cancer,” the authors wrote.
The study is limited by its retrospective nature and a lack of patient-level data on HPV status. The researchers did not have information on neuropathy, hearing loss, treatment toxicity, or disease progression.