Body composition analysis within 1 month after gastrectomy for gastric cancer.

Background: A significant body weight loss (BWL) is observed during 1 month after gastrectomy for gastric cancer. However, it remains unclear which body component mainly accounts for the weight loss.
Methods: Two-hundred forty-four patients who underwent gastrectomy for gastric cancer between May 2010 and October 2013 were examined. Body weight and composition were evaluated by a bioelectrical impedance analyzer within 1 week before surgery (first measurement), at 1 week after surgery (second measurement), and at 1 month after surgery (third measurement). The changes in the early period were defined as the differences until the second measurement, and those in the late period were defined as the differences from the second to the third measurement.
Results: Total BWL within 1 month was -3.4 kg, and the rate of body weight at 1 month to the preoperative body weight was 94.1 %. BWL was significantly greater in the early period than in the late period (-2.1 kg vs -1.2 kg, p < 0.001). In the early period, loss of lean body mass was significantly greater than loss of fat mass (-1.5 kg vs -0.6 kg, p < 0.001). The same trend was observed when the subset of patients who had surgical morbidities was excluded.
Conclusion: BWL during the first week after surgery was significantly greater than that during the subsequent 3 weeks. Furthermore, loss of lean body mass accounted for a significant part of the BWL during the first week.