Zhongguo aizheng zazhi (Aug 2022)

The effect of the interaction between body mass index and age on the prognosis of breast cancer

  • XIAO Jialong, MO Miao, ZHOU Changming, WANG Zezhou, SHEN Jie, YUAN Jing, YU Keda, LIU Guangyu, WU Jiong, SHEN Zhenzhou, SHAO Zhimin, ZHENG Ying

DOI
https://doi.org/10.19401/j.cnki.1007-3639.2022.08.007
Journal volume & issue
Vol. 32, no. 8
pp. 719 – 726

Abstract

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Background and purpose: Currently, several studies have demonstrated that body mass index (BMI) is a prognostic factor in breast cancer. The study aimed to assess the association pattern of BMI with mortality risk among patients of different age groups. Methods: This retrospective cohort study included the clinical characteristics and survival status of 25 629 patients diagnosed with breast cancer and subsequently hospitalized in Fudan University Shanghai Cancer Center between January 1, 2008 and December 31, 2016. The association between BMI and prognosis of breast cancer patients in different age subgroups was analyzed using Cox proportional hazards regression model with restricted cubic splines adjusting the main prognostic factors. Results: BMI and age were both influencing factors of breast cancer prognosis, and there was a significant interaction (P = 0.011). The pattern of association between risk of death and BMI differed among different age groups. A "J-shaped" association between risk of death and BMI was observed in the patients younger than 35 years, with a BMI of 20.16 kg/m2 corresponding to the lowest risk of death. In the age group of 35-60 years, no significant change in the risk of death was observed in patients with BMI below 23 kg/m2, and the risk of death in patients with BMI above 23 kg/m2 increased with increasing BMI; A "U-shaped" association between risk of death and BMI was observed in the patients older than 60 years, with a BMI of 23.86 kg/m2 being the lowest. The risk of death was more sensitive to changes in BMI in patients aged less than 35 years than in those aged 35-60 years and those aged more than 60 years. Conclusion: BMI and age have a significant interaction in the prognosis of breast cancer when adjusted for potential confounding factors. The association pattern between the risk of death and BMI of patients in different age groups is different. For patients under 35 years old, the lowest risk of death corresponds to BMI at diagnosis of about 20 kg/m2, while for patients over 60 years old, the lowest risk of death corresponds to a BMI at diagnosis of about 24 kg/m2.

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