Prognostic significance of abdominal obesity and its post-diagnosis change in a Chinese breast cancer cohort.

PURPOSE: It is well-known that obesity has an adverse impact on breast cancer prognosis; nonetheless, the prognostic role of abdominal obesity, especially its post-diagnosis change, has been understudied. This study aims to examine the prospective associations of general and abdominal obesity and their post-diagnosis changes with all-cause mortality, breast cancer-specific mortality, and breast cancer recurrence in Chinese breast cancer patients. METHODS: From 2011 to 2014, 1460 Chinese breast cancer patients were recruited and followed up at 18, 36, and 60 months after diagnosis. Body mass index (BMI), waist-to-hip ratio (WHR), and their changes between baseline and 18-month follow-up were derived. Clinical records on diagnosis, treatment, and death were also obtained. In total, 1309 women who completed the 18-month follow-up were included for Cox regression analyses, stratified by follow-up periods. RESULTS: Within 18-48 months post-diagnosis, substantial WHR loss (5% or above) had reduced risk of all-cause (HR = 0.21 [95% CI 0.06-0.75]) and breast cancer-specific mortality (0.21 [0.06-0.77]) relative to stable WHR; whereas after 48 months post-diagnosis, substantial WHR gain showed elevated risks of all-cause mortality (2.67 [1.22-5.85])). Higher baseline WHR was also associated with both mortality outcomes. Nonetheless, no such associations were observed for BMI measures. Also, the effects of obesity measures on breast recurrence were less apparent. CONCLUSION: Abdominal obesity, rather than general obesity, was linked to worse survival in Chinese breast cancer patients. Prevention on abdominal obesity and waist gain following breast cancer diagnosis may have a beneficial effect on longer-term survival over and above conventional weight management. Waist assessment and abdominal obesity control should therefore be incorporated as a vital component of the evaluation and interventions of breast cancer prognosis.