Patients Treated with Preoperative Chemoradiation for Pancreatic Ductal Adenocarcinoma have Impaired Bone Density, a Predictor of Distant Metastasis

Pancreatic ductal adenocarcinoma (PDAC) is a lethal neoplasm that spreads to surrounding tissue or distant sites. This study investigated distant metastases in PDAC patients with or without preoperative chemoradiation therapy (CRT), focusing on vitamin D levels and bone density. This study included 146 patients with PDAC who underwent surgery from 2007 to 2014. Bone density was evaluated using computed tomography, and the preoperative vitamin D level was calculated by enzyme-linked immunosorbent assay (ELISA) for patients with available plasma (48 cases). When the patients were divided into two groups according to the change in bone density, the group with decreased bone density had a shorter distant metastasis-free survival time (DMFS) after surgery than the other group (p < 0.05). Low vitamin D was a weak predictor of DMFS, but the difference was not significant (p = 0.08), perhaps because of the sample size. Multivariate analysis indicated three significant factors associated with distant metastasis: a decrease in bone density (hazard ratio [HR], 2.17; p = 0.04), normalization of the Dupan-2 value after surgery (hazard ratio [HR], 0.39; p = 0.02), and completion of adjuvant chemotherapy (HR, 0.29; p < 0.01). Univariate analysis showed that a low vitamin D concentration (< 20 pg/ml) was a risk factor (p = 0.04) for bone density change. Multivariate analysis found that preoperative CRT was the only factor associated (+/-, OR, 5.8; p = 0.04) with bone density change, suggesting that preoperative CRT significantly decreases bone density in patients with insufficient vitamin D. Patients treated with preoperative CRT tend to have impaired bone density, which is a predictor of distant metastasis. Thus, vitamin D supplementation may decrease distant metastasis.