HIF1A and neoplasm: Even though iodine-125 (125I) brachytherapy has emerged as a highly effective palliative treatment option for advanced esophageal cancer, the development of resistance to 125I brachytherapy due to tumor hypoxia and activation of the hypoxia-inducible factor 1 (HIF-1) signaling pathway poses a significant limitation in the management of esophageal cancer.