C00-C97: Malignant neoplasms

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

Malignant neoplasms of ill-defined, secondary and unspecified sites refer to a group of cancerous growths that arise from different areas in the body, but are not clearly identified or classified according to their primary area of origin. These cancers might either be "secondary," implying they have spread or 'metastasized' from their initial site to other parts of the body, or "unspecified," indicating that the exact location or source of the cancer hasn't been determined. Common symptoms include unintentional weight loss, persistent fatigue, pain that doesn't go away, skin changes, and changes in bowel or bladder habits, all depending on the region affected. The diseases in this group usually progress by growing unhindered and invading neighbouring tissues, or spreading through the body's blood or lymph systems, which can result in life-threatening complications.