膀胱癌預後中的肥胖悖論 : 台灣健保資料庫的分析

江亭易¹、曾文歆^1,2黃冠華¹、邱文祥³

台南永康奇美醫院 外科部 泌尿科¹；國立中山大學生物醫學研究所²；台北馬偕醫院 泌尿科³

Navigating the Obesity Paradox in Bladder Cancer Prognosis – Insights from the Taiwan National Health Insurance System Database

Ting-Yi Chiang¹、Wen-Hsin Tseng^1,2、Steven K. Huang¹、Allen W.Chiu³

¹Division of Urology, Department of Surgery, Chi Mei Medical Center, Tainan, Taiwan;

²Institute of Biomedical Science, National Sun Yat-Sen University, Kaohsiung, Taiwan;

³Department of Urology, Mackay Memorial Hospital, Taipei, Taiwan.

Purpose:

Globally, bladder cancer is a prevalent malignancy in the urinary system. While overweight and obesity are associated with an increased risk of bladder cancer, some studies suggest that obesity may paradoxically lead to better survival outcomes in bladder cancer patients—a phenomenon known as the obesity paradox. This study aims to examine the association between BMI and bladder cancer, using nationally representative data from the Taiwanese population and stratifying the analysis based on cancer stages.

Materials and Methods:

We conducted a retrospective analysis of 15,086 patients diagnosed with bladder cancer using the Taiwan National Health Insurance System Database. Exclusions were made for patients with clinical stage 0 or missing data, lack of information on weight or height, unrecorded details on smoking, drinking, or betel nut chewing, and an age below 20. Body Mass Index (BMI) was classified into three groups: underweight (BMI<18.5), normal weight (18.5≤BMI<25), and overweight (BMI≥25), following the conventional WHO classification. A total of 10,352 patients were included and categorized based on the aforementioned BMI criteria. The study focused on outcomes such as disease-free survival and overall survival rates, with subgroup analysis stratified by clinical stage.

Results:

The higher BMI cohort, statistically significant for being younger and predominantly male, demonstrated increased comorbidities but also a more favorable prognosis, including lower overall mortality, reduced bladder cancer-specific mortality, and an extended survival period. Adjusted Cox regression analyses revealed that overweight patients had a reduced risk of both overall and cancer-specific mortality compared to normal-weight individuals, while underweight patients showed an increased risk. Subgroup analysis consistently showed lower mortality rates in overweight patients, significant across genders and in overall and cancer-specific mortality. Stratification by clinical stage indicated an increased risk in underweight patients in stages I-III, with an exception in stage IV. Overweight patients exhibited significantly lower overall and cancer-specific mortality rates across all stages, except for cancer-specific mortality in stage I patients

Conclusion:

This study in the Taiwanese population revealed that overweight patients exhibited a more favorable prognosis, aligning with the concept of the obesity paradox. This observed relationship appears consistent across all cancer stage groups, with some exceptions, providing potential avenues for further investigation in future research.