Metastases with definitive pathological diagnosis but no detectable primary tumor: A surveillance epidemiology and end results‐based study

• Published in: Cancer medicine (Malden, MA) MA), 2019-10, Vol.8 (13), p.5872-5880
• Main Authors: Tao, Lianyuan, Yu, Haibo, Dong, Yadong, Tian, Guanjing, Ren, Zhiyuan, Li, Deyu
• Format: Article
• Language: English
• Subjects: Aged; cancer of unknown primary site; Cancer therapies; Chemotherapy; Clinical Cancer Research; Diagnosis; Epidemiology; Female; Humans; Lung cancer; Lymph nodes; Male; Medical prognosis; Melanoma; Metastases; Metastasis; Middle Aged; Neoplasms, Unknown Primary - diagnosis; Neoplasms, Unknown Primary - epidemiology; Neoplasms, Unknown Primary - pathology; Original Research; Patients; Prognosis; SEER; SEER Program; Skin cancer; Studies; Surgery; Surveillance; survival; Survival analysis; Tumors
• ISSN: 2045-7634; 2045-7634
• DOI: 10.1002/cam4.2496

Background This study investigates the characteristics of a special type of cancer of unknown primary site (CUP, type 2), which is a metastasis of a definite pathological diagnosis without a detectable primary site. Patients and methods Patients diagnosed between 2004 and 2014 were identified from the Surveillance Epidemiology and End Results (SEER) database. The characteristics of type 2 CUP from different sources were analyzed. For each source of type 2 CUP, tumors of the corresponding TnN0‐XM1 stage were used as controls. Results A total of 8505 patients with type 2 CUP were included in this analysis. Type 2 CUP shows an increasing trend, while type 1 shows the opposite. Type 2 CUPs have significant differences with stage IV of the same pathological primary lesion. Many characteristics influenced the prognosis of type 2 CUP patients, including marital status, age, race, sex, registration time, lymph node metastasis, surgery, chemotherapy, and radiation. Conclusion Our study suggests that identifying the source of metastasis is the key to the selection of treatment and the determination of the prognosis for CUP. The number of type 2 cancer of unknown primary site (CUP) (metastatic cancer that the tissue or organ source can be determined but not the primary tumor, T0N0‐XM1) is increasing. Type 2 CUP (T0N0‐XM1) is a special cancer status, whose clinical characteristics and prognosis are significantly different from the classical CUP (type 1 CUP) and corresponding TnN0‐XM1. Identifying the source of metastatic focus is the key to the selection of treatment and prognosis for CUP.