Cancer of unknown primary (CUP) represents a heterogeneous group of metastatic tumors that lack an identifiable primary site despite an extensive diagnostic work-up. It is a well-recognized entity that is characterized by early dissemination, aggressive clinical course, unpredictable metastatic pattern, intrinsic treatment resistance, and a dismal prognosis. Despite the molecular diagnostic workup and personalized therapy, the expected improvements in the diagnosis and treatment of CUP have not been achieved. Comparative oncology has a promising role in the exchange of knowledge and practices between humans and canines. Therefore, we intended to review the literature reporting on CUP in dogs in order to identify some interesting parallels and unique results that could be transposed to in-human research.

原发性癌症（CUP）代表了一组异质性转移性肿瘤，尽管进行了大量的诊断工作，但它们仍缺乏可识别的原发部位。它是一个公认的实体，其特点是早期传播，积极的临床过程，不可预测的转移模式，内在治疗抗性和预后不良。尽管进行了分子诊断工作和个性化治疗，但在CUP的诊断和治疗方面仍未实现预期的改进。比较肿瘤学在人类与犬类之间的知识和实践交流中发挥着有希望的作用。因此，我们打算回顾有关狗中银联的文献报道，以发现一些有趣的相似之处和独特的结果，这些结果可能会转化为人体研究。