原发部位不明的癌症 (CUP) 是一组异质性癌症，其中已发现转移，且现有诊断方法无法检测到原发肿瘤。 CUP 是一种尚未得到充分研究的疾病，其生物学特性尚不清楚。 CUP的临床特征多种多样，但患者的预后通常较差，根治性治疗的可能性有限。微生物组是人体内微生物的基因和基因产物。近年来，由于新一代测序的使用，可以评估微生物组对人体功能的影响。头颈癌由于该区域微生物群丰富而受到其影响，生态失调可能是癌症发生的危险因素。这项工作的目的：本研究的目的是评估原发部位不明的癌症患者的预后因素、临床特征（包括微生物组）和治疗结果。在研究组中，拟杆菌门、梭杆菌、检测到芽孢杆菌门、放线菌门、放线菌门和候选菌门，而检测到少量厚壁菌门和变形菌门。 CUP 发生的独立预测因子如下：白细胞计数最多 6.49 × 103/mm，微生物组中变形菌门细菌低于 11.6%，厚壁菌门低于 22.1%，放线菌至少 11.0%。卟啉单胞菌和梭杆菌数量的增加与放疗并发症的风险和生存率缩短有关。由于对此问题缺乏共识，CUP患者的临床诊断和治疗变得复杂和困难。 CUP患者的治疗和预后并不理想。微生物组对癌症的发展、病程和治疗的影响的临床价值变得越来越重要。微生物组可能成为抗癌治疗反应及其并发症风险的标志。微生物组的免疫调节为进一步研究提高肿瘤治疗的有效性提供了机会。梭杆菌和卟啉单胞菌似乎是癌症发展中最重要的细菌，它们也会增加放疗并发症的风险并缩短患者的生存率，从而恶化患者的预后。链球菌和乳酸菌似乎是可以降低癌症风险、并发症风险并改善患者预后的细菌。总蛋白缺乏和炎症标志物升高也是癌症风险的重要预测因素。

cancer of unknown primary site (CUP) is a heterogeneous group of cancers in which metastases are found, and the primary tumor is not detected with available diagnostic methods. CUP is a disease that has not been fully researched, and its biology is unclear. The clinical characteristics of CUP are variable, but the prognosis of patients is usually unfavorable, and the possibilities of radical treatment are limited. The microbiome is the genes and gene products of microorganisms residing in a human body. In recent years, thanks to the use of next-generation sequencing, it is possible to assess the impact of the microbiome on human body functions. Head and neck cancers, due to the rich microbiome of this area, are influenced by it, and dysbiosis may be a risk factor for the development of cancer. Objective of this work: the aim of this study was to evaluate prognostic factors, clinical features including the microbiome, and treatment outcomes in patients with cancer of unknown primary site.in the study group, increased numbers of bacteria of the phyla Bacteroides, Fusobacteria, Bacillota, Actinomycetota, Actinobacteria, and Candidatus were detected, while Firmicutes and Proteobacteria were detected in smaller numbers. Independent predictors of CUP occurrence were the following: leukocyte count of at most 6.49 × 103/mm, bacteria from the Proteobacteria phylum in the microbiome below 11.6%, Firmicutes below 22.1%, and Actinobacteria at least 11.0%. Increased numbers of Porphyromonas and Fusobacterium bacteria were associated with the risk of radiotherapy complications and shortened survival rate.clinical diagnosis and treatment of patients with CUP is complicated and difficult due to the lack of consensus on this issue. Treatment and prognosis of patients with CUP is unsatisfactory. The clinical value of the influence of the microbiome on the development, course, and treatment of cancer is becoming increasingly important. The microbiome may become a marker of response to anticancer treatment and the risk of its complications. Immunity modulation with the microbiome provides opportunities for further research on improving the effectiveness of oncological treatment. Fusobacterium and Porphyromonas seem to be the bacteria most important for the development of cancer, also worsening the prognosis of patients by increasing the risk of complications of radiotherapy and shortening the survival rate of patients. Streptococcus and Lactobacillus seem to be bacteria that reduce the risk of cancer, reduce the risk of complications, and improve the prognosis of patients. Total protein deficiency and elevated inflammatory markers are also important predictors of cancer risk.