Survival analysis of clear cell renal carcinoma according to the Charlson comorbidity index

We assessed the convenience of elective surgery for clear cell renal carcinoma with regard to overall survival in accordance with established comorbidity criteria.

This retrospective study included all patients with a histological diagnosis of clear cell renal carcinoma diagnosed between July 1, 1983 and June 1, 2006 in a population of 200,000 inhabitants. All tumors were classified in stages according to the classification of the American Joint Committee on Cancer based on the 2002 UICC TNM classification. Comorbidity in each patient was assessed by the Charlson comorbidity index. Study variables were gender, age, smoking, Charlson index, Charlson index 2 or less and greater than 2, tumor stage, localized stage and locally advanced or metastatic stage. The chi-square or Fisher exact test, or ANOVA was used to analyze the groups, as applicable. Survival associated with each tumor stage and comorbidity group was evaluated by the Kaplan-Meier test. Similarly a binary logistical regression model was used to assess survival after 1, 5 and 10 years. No minimum followup was established for including a patient in the analysis. SPSS, version 12.0 for Windows software was used for statistical analysis with a probability of the null hypothesis of lower than 0.05 considered significant.

A total of 232 renal masses were diagnosed during the study period, of which 192 (82.7%) were useful for the study. There were no significant differences between the genders in age (p = 0.486), stage (p = 0.659) and Charlson index (p = 0.463). Median followup was 1,416 days. Of the 192 patients 33 (17.2%), 28 (14.6%), 32 (16.7%), 29 (15.1%), 32 (16.7%) and 38 (19.8%) showed a Charlson index of 1 to 5 or greater, respectively. Stage was I to IV in 29 (15.1%), 69 (35.9%), 40 (20.8%) and 47 cases (24.5%), respectively. It proved impossible to determine tumor stage in 4 cases (2.1%). There were 72 deaths (37.5%), including 25 (34.7%) from intercurrent disease and 45 (62.5%) from clear cell renal carcinoma. The cause of death could not be determined in 2 cases (2.8%). Survival analysis revealed significant differences in overall survival according to stage (p <0.001) and Charlson index (p = 0.02), between localized stages and locally advanced or metastatic stages (p <0.001) and between patients with a Charlson index of 2 or less vs greater than 2 (p <0.001), particularly in those with local stage (p <0.001) but not in those with locally advanced or metastatic stage (p >0.05). In the logistical regression model tumor stage and the comorbidity index were prognostic factors after 1 year (B exponential 2.4 and 1.3, respectively, p <0.05), after 5 years (B exponential 1.6 and 1.3, p <0.05) and after 10 years (B exponential 1.5 and 1.4, respectively, p <0.05). The first was of greatest importance for short-term survival.

Patients with localized clear cell renal carcinoma and a comorbidity index of greater than 2 may choose observation as treatment for the condition.