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Body mass index and body shape before treatment and nasopharyngeal carcinoma prognosis: A population-based patient cohort study in southern China |
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| Authors: | Yun Du Ruimei Feng Ellen T. Chang Li Yin Tingting Huang Yancheng Li Xiang Zhou Yi Huang Feng Zhou Canqiong Su Xue Xiao Weihua Jia Yuming Zheng Hans-Olov Adami Yixin Zeng Yonglin Cai Zhe Zhang Miao Xu Weimin Ye |
| Affiliation: | 1. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden;2. Department of Epidemiology and Health Statistics and Key Laboratory of Ministry of Education for Gastrointestinal Cancer, Fujian Medical University, Fuzhou, China;3. Department of Epidemiology and Biostatistics, University of California, San Francisco, California, USA;4. Department of Radiation Oncology, The First Affiliated Hospital of Guangxi Medical University, Nanning, China Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China;5. Guangxi Health Commission Key Laboratory of Molecular Epidemiology of Nasopharyngeal Carcinoma, Wuzhou Red Cross Hospital, Wuzhou, China;6. State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, China;7. Key Laboratory of High-Incidence-Tumor Prevention & Treatment (Guangxi Medical University), Ministry of Education, Nanning, China Department of Otolaryngology-Head & Neck Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, China;8. Medical affair Office, Sun Yat-sen University Cancer Center, Guangzhou, China;9. Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden Clinical Effectiveness Research Group, Institute of Health and Society, University of Oslo, Oslo, Norway |
| Abstract: | A concern of reverse causation exists about the association between nasopharyngeal carcinoma (NPC) prognosis and body mass index (BMI) at diagnosis, while the prognostic impact of BMI measured years before diagnosis is unknown. Therefore, we investigated associations of prediagnosis and pretreatment BMI and body shape on NPC mortality. From a population-based patient cohort in southern China between 2010 and 2013, we included 2526 incident NPC cases with prospective follow-up through 2018. We assessed the associations of BMI and body shape at age 20 years, 10 years before diagnosis, and at diagnosis with NPC mortality, combining strategies of stratification and statistical adjustment to minimize reverse causation. We observed 25% lower all-cause mortality (hazard ratio [HR] 0.75, 95% confidence interval [CI]: 0.64-0.89) and 25% lower NPC-specific mortality (HR 0.75, 95% CI: 0.61-0.91) among overweight vs normal-weight NPC cases at diagnosis. Lean body shapes 1 and 2 at diagnosis were associated with 68% and 23% higher all-cause mortality, respectively, compared to normal body shape 3. No effect modification by cancer stage was detected for associations with all-cause or NPC-specific mortality. Associations with BMI and body shape 10 years before diagnosis were similar but attenuated, while body size and shape at age 20 were not associated with mortality. Being overweight at diagnosis decreased mortality, and thinner body shape increased mortality, compared to normal weight/body shape. These associations may be due to poorer nutrition and treatment intolerance, resulting in treatment discontinuation and worse survival outcomes. |
| Keywords: | body mass index body shape nasopharyngeal carcinoma prognosis residual confounding reverse causation |