The simultaneous manifestation of five independent primary tumors within a single patient: A case study

Introduction Head and neck squamous cell carcinomas (HNSCC) are among the ten most widespread cancers worldwide. Malignancies that share common risk factors, such as tobacco or alcohol consumption, may occur together as a result of field cancerization. Multiple primary malignancies (MPMs) represent a rare phenomenon in which two or more independent primary malignancies emerge either simultaneously or sequentially within a single patient. MPMs are classified as synchronous when the malignancies are diagnosed at the same time as the primary tumor or within six months of each other. On the contrary, metachronous MPMs occur when the malignancies are diagnosed after six months but within five years of the diagnosis of the primary tumor.