381. progressive loss of bone density in patients with esophageal cancer

Abstract Background Changes in body composition are common in esophageal cancer (EC). A majority of patients, regardless of stage, display signs of cachexia, including weight loss, skeletal and cardiac muscle atrophy and fat wasting. Bone loss is also common in cancer, secondary to shared signaling pathways that contribute to lean body loss. In this study, we hypothesized that bone density decreases progressively in patients with EC and that the continued loss of bone associated with oncologic outcomes. Methods We performed a retrospective review of all patients that received esophagectomy between 2012 and 2020 at our facility. Body composition was measured using PET/CT scans, and patients were classified by muscle mass according to sex- and BMI-dependent cutoffs. Bone density was measured by determining the radiation attenuation of the lumbar (L1-L5) vertebral bodies. The change in bone density was normalized by time and compared to tumor pathologic variables. A p-value less than 0.05 was considered statistically significant. Results Bone density was significantly reduced in patients with cachexia relative to those with appropriate muscle mass (108 ± 37.2 HU v. 146 ± 55.0 HU, p = 0.003). Furthermore, bone density correlated with muscle mass (p < 0.00001, R = 0.5055) and muscle quality/radiodensity (p = 0.0002, R = 0.4736). Mean rate of bone loss was −12.0 ± 27.9 HU/100d. Patients with regional lymph node metastases at surgery had more bone loss than those with N0 disease (−26.6 ± 30.8 HU/100d v. -2.71 ± 22.1 HU/100d, p = 0.03). Similarly, patients with positive lymphovascular invasion (−41.8 ± 32.6 HU/100d v. -3.53 ± 20.1 HU/100d, p = 0.005) and positive perineural invasion (−29.8 ± 32.4 HU/100d v. -3.12 ± 21.1 HU/100d, p = 0.01) progressively lost more bone. Conclusion Reduced bone mineral density is a key component of cachexia in patients with EC. We demonstrate herein that osteopenia in EC patients associates with several cachexia measures and that progressive loss of bone may predict early metastasis. Bone density may serve as a strong predictor of survival and stratification tool for clinical trials. These findings further highlight the need to study mechanisms that lead to bone wasting in tumor bearing hosts.