Effectiveness of Late Line Palliative Chemotherapy by Specialised Approach to Cancer of Unknown Primary: A Case Report

Background: Cancers of unknown primary (CUPs) are defined as histologically confirmed metastatic tumours whose primary site cannot be identified during standard pretreatment evaluation. No specific regimen can be recommended as standard of care. Taxanes and platinum-based regimens are commonly used in the first-line treatment of CUPs, but there is no specific regimen for after second-line treatment. In general, late line chemotherapy is not recommended, but we experienced a rare case of CUPs with disseminated disease that showed improvement with fifth-line palliative chemotherapy by specialised approaches based on the reconsideration of histologic type of cancer. We report a rare case in which palliation was achieved by late line chemotherapy based on pathological review. Case: The case was a 65 year-old man. Transverse colectomy and peritoneal metastasectomy were performed for CUPs. The chemotherapy was continued for 3 years afterwards, and the fourth treatment was not effective. The pathological reexamination was carried out in examining the 5th line treatment, and the chemotherapy (pazopanib) was started under the diagnosis of epithelioid sarcoma. The tumor did not shrink, but the antipyretic effect on tumor fever was achieved, resulting in palliation of symptoms. Conclusions: In general, late line chemotherapy for CUPs is not recommended, but palliative chemotherapy based on pathologic profile may be effective and relieve symptoms of CUPs.