Ethnic variation of the histological subtypes of renal cell carcinoma in Singapore

Abstract

Introduction: The purpose of this study is to determine how the histological subtypes of renal cell carcinoma (RCC) vary among the heterogeneous Singaporean population and how this affects the survival rate. Patients and methods: The data analyzed in this retrospective study of the histological subtypes of RCC cases treated in Singapore General Hospital over a ten year period (2001–2010) were obtained from the Cancer Registry of the hospital’s department of urology. Statistical analysis was done using the Statistical Package Service Solution (SPSS) version 17.0 software. Chi Square and z-tests were used where appropriate; a p value <0.05 was considered significant. Results: The records of 676 patients studied showed that 80.8% of the patients were Chinese, while Malays, Indians and other minor groups accounted for 6.5%, 4.6% and 8.1%, respectively. The mean age (SD) at presentation was 58.1 (12.1), 57.6 (10) and 55.1 (9.6) years for the Chinese, Indians and Malays, respectively. The commonest histological variant in each of the ethnic groups, irrespective of sex, was clear cell carcinoma which accounted for 79.7% of all the histological subtypes found in Chinese, for 70.5% in Malaysian and 77.4% in Indian patients. The sarcomatoid histological subtype was found in 4.3% of the studied population with a high prevalence in the Indian ethnicity (9.7%). The worst survival rate (33.3%) was recorded among Malays with the papillary cell subtype, and also in the Chinese population the highest mortality rate was found in cases with the papillary cell subtype (16.9%). Conclusion: The commonest histological subtype of RCC in each of the studied ethnic groups in Singapore is clear cell carcinoma. However, most of the cancer deaths in Chinese (16.9%) and Malays (66.7%) were associated with the papillary cell type, while in Indians the sarcomatoid component prevailed (9.7%). Thus, the usual prognostic trend for RCC subtypes cannot be applied to all Singaporean ethnicities, necessitating individualization of prognosis for each group.