THE IMPORTANCE OF CORRECT STAGE GROUPING IN ONCOLOGY - RESULTS OF A NATIONWIDE STUDY OF OROPHARYNGEAL CARCINOMA IN THE NETHERLANDS

Background. In the frame of a nationwide study of oropharyngeal carcin oma in the Netherlands (1986-1990), the current International Union Ag ainst Cancer 1992/American joint Committee on Cancer 1988 staging syst em was evaluated with respect to patient distribution and prognostic v alue. Methods. Data related to epidemiology, treatment and survival fr om 640 patients referred for primary treatment were analyzed. Staging was first evaluated in a proportional-hazard regression analysis contr olled for these data. Next, all possible combinations of T, N, and M w ere tested in a stepwise backward elimination model until all remainin g indicator variables had a P value of less than 0.05. New stages were defined, based on the coefficients of the remaining indicator variabl es. Results. The revised stages revealed two advantages compared with the UICC 1992/AJCC 1988 version: a more balanced distribution of patie nts (31% in Stage I, 31% in Stage II, 18% in Stage III, 14% in Stage I V, and 5% unknown in the revised staging system versus 7% in Stage I, 17% in Stage II, 24% in Stage III, 50% in Stage IV, and 2% unknown in the UICC 1992/AJCC 1988 staging system), and an improved prognostic di scrimination for the disease specific survival (5-year results in the revised staging were 67% in Stage I, 42% in Stage II, 28% in Stage III , and 11% in Stage IV, versus 68% in Stage I, 64% in Stage II, 44% in Stage III and 27% in Stage IV in UICC 1992/ATCC 1988). Conclusion. Imp rovements in the current staging system in patient distribution in the stages in prognostic discrimination is feasible by regrouping the T, N, and M but without redefining the categories themselves.