Multivariate analyses to assess treatment effectiveness in advanced head and neck cancer.

OBJECTIVE To assess relative benefit of combined radiotherapy and surgery over single-modality treatment for advanced-stage squamous cell carcinoma of the aerodigestive tract by means of several multivariable analyses to control for patient variables. DESIGN Medical chart review. SETTING University medical center. PATIENTS AND METHODS The study included 532 patients receiving initial therapy between January 1, 1980, and December 31, 1989. Three multivariate techniques (multiple logistic regression, propensity score stratification, and conjunctive consolidation) were used to compare outcomes for treatment groups. MAIN OUTCOME MEASURE Five-year survival. RESULTS Survival for radiation, surgery, and combined treatment groups were 24%, 40%, and 46%, respectively. With the use of multiple logistic regression to control patient variables, the radiation group had a significantly lower survival than the combined therapy group (risk ratio, 2.24; 95% confidence interval, 1.32-3.80), while there was no statistical difference for the surgery group compared with the combined therapy group (risk ratio, 1.26; 95% confidence interval, 0.78-2.03). When analyzed by propensity score, 5-year survival was higher in each quintile for the combined therapy group than for the group who received radiation alone (P =.002). There was no significant difference in survival between the surgery and combined treatment groups (P =.25). Conjunctive consolidation was used to create a clinical staging system to compare outcomes across treatment groups. In each clinical severity stage, radiation alone had a lower survival than combined therapy (P =.001), while no statistical difference was noted between surgery and combined therapy (P =.50). CONCLUSIONS All 3 statistical techniques showed a significantly lower survival for patients treated with radiation alone vs combined therapy. No significant difference was noted between surgery and combined therapy. Propensity score analysis and conjunctive consolidation are useful techniques to control prognostic variables in cancer database studies and should be used in future outcome studies that address more current treatment dilemmas in head and neck oncology.