Changes in bone metabolism after gastric cancer surgery in male patients: a prospective observational study.

Background: Several retrospective studies have shown that bone disorders occur after gastric cancer surgery. This study was designed to prospectively evaluate the changes in bone metabolism after gastrectomy for gastric cancer.
Methods: We prospectively enrolled 39 men with early gastric cancer who underwent gastrectomy. We excluded women to avoid the effects of menopause. We employed dual energy X-ray absorptiometry (DEXA) to measure bone mineral density (BMD) of the lumbar spine. DEXA was performed before and 1 and 2 years after surgery. The serum levels of alkaline phosphatase (ALP), 1,25-dihydroxy vitamin D [1,25(OH) ₂ VD], 25-hydroxy vitamin D [25(OH)VD], and estradiol were measured before surgery and every 3 months until 2 years after surgery.
Results: DEXA revealed that BMD significantly decreased by 0.036 ± 0.033 g/cm ² 12 months after gastrectomy (P < 0.001) and by 0.046 ± 0.040 g/cm ² 24 months after gastrectomy (P < 0.001). The serum ALP level significantly increased by 38.31 ± 103.8 IU/L 24 months after surgery (P = 0.013). The serum 25(OH)VD level significantly decreased by 4.88 ± 6.42 ng/ml 24 months after surgery (P < 0.001), whereas the serum 1,25(OH) ₂ VD levels were consistently in the normal range. The serum estradiol level significantly increased by 2.94 ± 7.49 pg/ml 12 months after gastrectomy (P = 0.035). A lower preoperative body mass index (BMI) significantly correlated with the reduction in BMD 12 months after surgery; the correlation coefficient was 0.37 (P = 0.025).
Conclusions: This study showed that a significant decrease in BMD was observed for up to 24 months after gastrectomy, not only 12 months.