Bone metastasis in esophageal adenocarcinoma and squamous cell carcinoma: a SEER-based study

Esophageal cancer is a common worldwide disease with a higher mortality rate. Studies on esophageal cancer patients with bone metastasis are rare. Our study focused on the clinicopathological features of patients with bone metastasis using the Surveillance, Epidemiology and End Results (SEER) database to further explore the risk factors and survival for bone metastasis.

Esophageal cancer patients with bone metastasis were extracted from the SEER database. Univariable analysis and multivariable logistic regression were used to study the risk factors for bone metastasis. Univariable analysis and multivariable Cox regression were performed to reveal the survival and prognostic factors for bone metastasis. The competitive risk model was made to compare the association with bone metastasis among different causes of death. Propensity score matching was used to reduce the bias.

Male, middle esophagus, with brain metastasis, without lung metastasis and without liver metastasis were major independent risk factors of bone metastasis. Older age, poorly differentiated and undifferentiated, with brain metastasis and with liver metastasis were major independent prognostic factors of bone metastasis. Patients with bone metastasis had a worse prognosis before and after propensity score matching than patients with other metastasis.

Esophageal cancer patients with male sex, middle esophagus and brain metastasis were more likely to have bone metastasis. Compared to patients with other metastatic sites such as liver, brain and lung, patients with bone metastasis had a worse prognosis. Our findings provide recommendations about clinical guidelines for esophageal cancer patients with bone metastasis.