Advanced esophageal cancer with bone metastases: Prognostic biomarkers and palliative treatment

Esophageal cancer (EC) is a common and devastating tumor of the upper digestive tract. Unfortunately, by the time any symptoms have manifested, the disease has often progressed to an advanced stage and is accompanied by macro- and micrometastases, including in the bones. The treatment of esophageal cancer with bone metastases remains clinically challenging, given the poor prognosis associated with this condition. Effective prognostic biomarkers can help medical staff choose the appropriate operation and treatment plan, that is for most beneficial for making patients. Current treatments for esophageal cancer with bone metastases include pain-relieving drugs, surgical therapy, radiotherapy (RT), chemotherapy (CT, including molecular-targeted drug therapy), endocrine therapy (ET), bisphosphonates (BPs) and interventional therapy. Of these robust measures, radiotherapy has emerged as a particularly promising therapy for bone metastases from esophageal cancer. Substantial progress has been made in radiation therapy techniques since the discovery of X-rays by Roentgen in 1895. In its palliative capacity, the key goals of radiotherapy are to relieve the patients' bone pain and debilitate effects, including relieving spinal cord compression, correcting the spinal deformity and restoring spinal stability. However, it is worth mentioning that RT for esophageal cancer has various side effects. Currently, the available studies focused exclusively on radiotherapy for ECBM are too small to draw any definitive conclusions, and each of these studies has significant limitations. In this review, in addition to the epidemiology described at the beginning, we will explore the current prognostic biomarkers and radiotherapy for esophageal cancer, with a particular focus on those with bone metastases.