{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T15:43:42Z","timestamp":1784907822365,"version":"3.55.0"},"reference-count":24,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2023,10,11]],"date-time":"2023-10-11T00:00:00Z","timestamp":1696982400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Oncol."],"abstract":"<jats:p>Cancers of unknown primary (CUP) account for 2%\u20135% of all diagnosed cancers and are always characterized with fast-paced aggression, early metastasis, and unpredictable spread patterns Mediastinum metastasis with unknown primary origin is extremely rare and with a poor prognosis and short survival. There is no literature to refer to for its treatment. Here, we reported a case of squamous cell CUP in the mediastinum. A 50-year-old male patient was admitted after multi-line treatment of low differentiated squamous cell carcinoma in the mediastinum diagnosed 8 months before. In August 2019, the patient went to a local hospital for cough and dyspnea for 2 weeks. Then, he was diagnosed with squamous cell carcinoma of unknown primary origin with multiple lymph nodes metastasis. The patient was featured with programmed cell death-ligand 1 (PD-L1) expression strongly positive in 90% of tumor cells and the combined positive score of 90 and a tumor mutation burden of 1.79 MUts\/Mb and microsatellite stable phenotype. The patient was treated with anti-programmed cell death-1 (PD-1) antibodies in combination with chemotherapy and responded to the treatment. The patient showed stable disease to multi-line immunotherapy for more than 7 months and finally got a clinical benefit of 2-year survival benefit. In conclusion, immunotherapy targeting PD-1\/PD-L1 in combination with chemotherapy may play a crucial role in the later-line treatment and palliative care of CUP.<\/jats:p>","DOI":"10.3389\/fonc.2023.1242460","type":"journal-article","created":{"date-parts":[[2023,10,11]],"date-time":"2023-10-11T07:20:49Z","timestamp":1697008849000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":2,"title":["2-Year survival benefit from immunotherapy for squamous cell cancer with cancer of unknown primary in mediastinum: a case 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