(ChemotherapyAdvisor) – The first quantitative assessment of treatment toxicity associated with adjuvant chemotherapy for advanced squamous cell carcinoma of the head and neck has found an insignificant effect on overall survival, with the majority of patients experiencing serious adverse events (AEs), according to a presentation at the 8th International Conference on Head and Neck Cancer, Toronto, Ontario, Canada, July 21-25.

“This study systematically reviewed all randomized clinical trials of chemoradiation therapy for advanced head and neck cancer conducted over the past 2 decades,” Jonathan George, MD, MPH, of the University of California, San Francisco, San Francisco, CA, and colleagues reported. They evaluated the association of AEs and overall survival (OS) benefit of chemotherapy “by using 2 epidemiologic assessments of treatment toxicity and efficacy—number needed to harm (NNH) and number needed to treat (NNT).”

A total of 68 randomized clinical trials that had 2 arms only—radiotherapy alone and combined chemoradiotherapy—were reviewed and analyzed and demographic data, survival data, and AE data for nearly 6,000 patients tabulated. Daily or twice-daily fractionated radiotherapy was administered in the radiotherapy alone arm; in the chemoradiotherapy arm, chemotherapy included concurrent cisplatin and 5-fluorouracil.

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“The NNT for overall survival was 15.4. NNH for grade 3-4 AEs was 4.3,” he noted. “Significant trends were seen of increased toxicity over time associated with adjuvant chemotherapy. Toxicity data were significantly more poorly summarized or tabulated, or were missing altogether, from studies before 2000. Low grade toxicity was nearly universally poorly measured.”

Using NNT and NNH, they found “that adjuvant chemotherapy has an insignificant effect on overall survival for 14 of 15 people treated, but that 3 of every 4 people treated with adjuvant chemotherapy will experience a serious adverse event. This calls into question claims that adjuvant chemotherapy provides an overall survival benefit in the treatment of advanced HNSCC, and sheds new light on the toxicity associated with adjuvant CT.”