Association of postoperative radiotherapy and body mass index with the incidence of breast cancer related lymphedema in Chinese patients / 中国肿瘤临床

ABSTRACT

Objective: To investigate the correlation between body mass index (BMI) and the incidence of breast cancer (BC) related lymphedema (BCRL) in Chinese patients over the period following postoperative radiotherapy (RT). Methods: This study included 281 female patients with single-sided BC who were treated at The Fourth Hospital of Hebei Medical University between November 2013 and February 2015. The clinical data of these patients were collected prospectively and analyzed. Based on their BMI, the patients were classified into three subgroups low BMI (BMI BMI>25, n=89), and high BMI (BMI≥28, n=98). The upper limb volume difference (ULVD) was compared between the diseased and healthy one. Univariate and multivariate generalized estimating equations (GEE) and linear logistic regression models were used to estimate the effects of RT and BMI on BCRL (defined as a ULVD ≥200 mL). In addition, these results were compared among the three BMI subgroups. Results: The mean ULVD before and after RT were 40.6 and 42.9 mL, respectively. The median ULVD before and after therapy remained constant at 30.0 mL; no significant difference was observed (P>0.05). Two and single patient respectively lacked one arm volume measurement before and after RT. The BCRL incidence rates in the low, middle, and high BMI subgroups before RT were 2.2% (2/93), 6.8% (6/88), and 13.3% (13/98); the corresponding rates after RT were 1% (1/93), 12.4% (11/89), and 12.2% (12/98), respectively. The GEE model indicated that RT did not cause an increase in the incidence rate of BCRL (P=0.529). Multivariable logistic regression for the middle and high BMI subgroups before RT (RR=4.199, P=0.693 and RR=10.999, P=0.002, respectively) and after RT (RR=13.287, P=0.047 and RR=14.308, P=0.029, respectively) indicated a significantly higher risk of BCRL in the high BMI subgroup . Similar results were obtained from the subgroup analyses of the middle BMI subgroup. Conclusions: The incidence and severity of BCRL do not decrease during the period following postoperative RT. Among Chinese BC patients, a lower threshold BMI of 28 kg/m2 appears to be associated with BCRL after RT. This is distinctly different from the commonly reported BMI threshold of 30 kg/m2 in most European and American studies.