C76-C80: Malignant neoplasms of ill-defined, secondary and unspecified sites

C80: Malignant neoplasm, without specification of site

A malignant neoplasm without specification of site, often referred to as cancer of unknown primary (CUP), is a term for a cancer that has metastasized to secondary locations in the body without a clear indication of where the original tumor formed. This group of conditions is generally characterized by rapid, uncontrolled growth of abnormal cells that can affect various systems in the body. Common symptoms might include fatigue, unexpected weight loss, or localized pain or discomfort depending on the areas affected by metastases. The specific cause is unknown, due to the unidentified origin of the primary site. Progression of the disease can vary from patient to patient, with some experiencing a more aggressive course. Unfortunately, the lack of a known primary site can complicate diagnosis and treatment strategies.