Research Progress of Multiple Primary Malignancies Associated With Esophageal Cancer

With the improvement in survival of patients with tumors, and continuous advancement of diagnostic technology and treatment modalities, instances of multiple primary malignancies (MPMs) are becoming an increasingly common phenomenon. The occurrence of esophageal-relevant MPMs increases the difficulty of diagnosis and treatment, and the overall prognosis is poor. Esophageal cancer related-MPMs tend to occur in areas such as the head, neck, stomach, and lungs. "Field cancerization" is one theoretical basis for the disease, and chemoradiotherapy, environmental life factors, and gene polymorphism are etiological factors. However, the influence of new therapeutic methods on MPM is still unclear, and the relationship between gene polymorphism and MPMs related to esophageal cancer needs further elucidation. Additionally, there is a lack of unified standards for diagnosis and treatment. Therefore, this study aimed to review the causes, clinical features, and prognostic factors of MPMs related to esophageal cancer.