Cancer of Unknown Primary: A Case Report on the Recognition of Its Clinical Entity and Standard of Care Management
- PMID: 40548152
- PMCID: PMC12180934
- DOI: 10.7759/cureus.86451
Cancer of Unknown Primary: A Case Report on the Recognition of Its Clinical Entity and Standard of Care Management
Abstract
Cancer of unknown primary (CUP) is a distinct and well-established clinical entity that encompasses a heterogeneous group of histologically proven cancers that present unique diagnostic and therapeutic challenges. This case describes a male patient in his late 60s who presented with nonspecific gastrointestinal complaints. A comprehensive workup, including clinical evaluation and various biochemical, imaging, and invasive histopathologic tests, led to the diagnosis of CUP following consultation with medical oncology specialists. A decision was made to forgo further invasive molecular tissue sampling in search of a primary malignant process in favor of initiating systemic chemotherapy. The patient possessed an unfavorable set of prognostic signs. Rapid clinical deterioration occurred the day after treatment initiation. A goals of care conversation led to a transition towards comfort measures only care, and the patient ultimately passed away. This case highlights the importance of non-oncologically trained providers recognizing CUP as its own entity to facilitate standard of care management. Future research is needed to establish benefits in clinical trials looking at molecular tumor profiling and site-specific therapies for this rare malignancy.
Keywords: cancer of unknown origin; cytokeratins; diagnostic mystery; immunohistochemistry (ihc); metastatic adenocarcinoma of unknown primary.
Copyright © 2025, Lazzaro et al.
Conflict of interest statement
Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.
Figures


Similar articles
-
Signs and symptoms to determine if a patient presenting in primary care or hospital outpatient settings has COVID-19.Cochrane Database Syst Rev. 2022 May 20;5(5):CD013665. doi: 10.1002/14651858.CD013665.pub3. Cochrane Database Syst Rev. 2022. PMID: 35593186 Free PMC article.
-
NIH Consensus Statement on Management of Hepatitis C: 2002.NIH Consens State Sci Statements. 2002 Jun 10-12;19(3):1-46. NIH Consens State Sci Statements. 2002. PMID: 14768714
-
Home treatment for mental health problems: a systematic review.Health Technol Assess. 2001;5(15):1-139. doi: 10.3310/hta5150. Health Technol Assess. 2001. PMID: 11532236
-
Systemic pharmacological treatments for chronic plaque psoriasis: a network meta-analysis.Cochrane Database Syst Rev. 2021 Apr 19;4(4):CD011535. doi: 10.1002/14651858.CD011535.pub4. Cochrane Database Syst Rev. 2021. Update in: Cochrane Database Syst Rev. 2022 May 23;5:CD011535. doi: 10.1002/14651858.CD011535.pub5. PMID: 33871055 Free PMC article. Updated.
-
Impact of residual disease as a prognostic factor for survival in women with advanced epithelial ovarian cancer after primary surgery.Cochrane Database Syst Rev. 2022 Sep 26;9(9):CD015048. doi: 10.1002/14651858.CD015048.pub2. Cochrane Database Syst Rev. 2022. PMID: 36161421 Free PMC article.
References
-
- Carcinoma of unknown primary (CUP) Pavlidis N, Fizazi K. Crit Rev Oncol Hematol. 2009;69:271–278. - PubMed
-
- Cancer of unknown primary: ESMO Clinical Practice Guideline for diagnosis, treatment and follow-up. Krämer A, Bochtler T, Pauli C, et al. Ann Oncol. 2023;34:228–246. - PubMed
-
- Key statistics for cancers of unknown primary. 2025. https://www.cancer.org/cancer/types/cancer-unknown-primary/about/key-sta... https://www.cancer.org/cancer/types/cancer-unknown-primary/about/key-sta...
-
- Molecular profiling diagnosis in unknown primary cancer: accuracy and ability to complement standard pathology. Greco FA, Lennington WJ, Spigel DR, Hainsworth JD. J Natl Cancer Inst. 2013;105:782–790. - PubMed
Publication types
LinkOut - more resources
Full Text Sources