Cell-free DNA (cfDNA) is derived from apoptosis/necrosis, active cellular secretion, and lysis of circulating cancer cells or micrometastases. In humans, cfDNA is widely used in cancer diagnosis, but veterinary research has yet to be actively conducted to establish it as a cancer biomarker. This retrospective study analyzed cfDNA levels in samples collected from dogs with neoplastic disease (n = 38), clinically ill dogs without neoplasia (n = 47), and healthy dogs (n = 35). cfDNA levels and clinical data were compared among groups, and prognostic analyses were performed within the neoplastic group. Furthermore, continual cfDNA measurements were performed during the chemotherapy of six dogs with lymphoma. Dogs with neoplasia showed significantly higher cfDNA concentrations than dogs without neoplasm, and the cfDNA oncentration in the lymphoid neoplasia group was significantly elevated among all neoplastic groups. Dogs with neoplasia and a plasma cfDNA concentration above 1,247.5 μg/L had shorter survival rates than those with levels below this threshold (26.5 vs. 86.1%, respectively, P < 0.05). In cases with complete remission in response to chemotherapy, the cfDNA concentration was significantly decreased compared with the first visit, whereas the cfDNA concentration was increased in cases with disease progression or death. Interestingly, a significant correlation was found between lymph node diameter and cfDNA concentration in dogs with multicentric lymphoma (R² = 0.26, P < 0.01). These data suggest that changes in cfDNA concentration could be used as a diagnostic biomarker for canine neoplasia. Furthermore, increased plasma DNA levels might be associated with shorter survival time, and cfDNA concentrations may reflect the response to chemotherapy.

无细胞 DNA (cfDNA) 源自细胞凋亡/坏死、活跃的细胞分泌以及循环癌细胞或微转移的裂解。在人类中，cfDNA 广泛用于癌症诊断，但尚未积极开展兽医研究以将其确立为癌症生物标志物。这项回顾性研究分析了从患有肿瘤疾病的狗身上收集的样本中的 cfDNA 水平。n = 38），临床病犬，无瘤形成（n = 47) 和健康的狗 (n= 35）。比较各组之间的 cfDNA 水平和临床数据，并在肿瘤组内进行预后分析。此外，在六只患有淋巴瘤的狗的化疗期间进行了持续的 cfDNA 测量。患有肿瘤的狗的 cfDNA 浓度显着高于无肿瘤的狗，并且淋巴样肿瘤组中的 cfDNA 浓度在所有肿瘤组中均显着升高。患有肿瘤且血浆 cfDNA 浓度高于 1,247.5 μg/L 的犬的存活率低于水平低于该阈值的犬（分别为 26.5% 和 86.1%，磷< 0.05)。在化疗后完全缓解的病例中，与首次就诊相比，cfDNA 浓度显着降低，而在疾病进展或死亡的病例中，cfDNA 浓度升高。有趣的是，发现多中心淋巴瘤犬的淋巴结直径与 cfDNA 浓度之间存在显着相关性。电阻² = 0.26，磷< 0.01)。这些数据表明，cfDNA 浓度的变化可用作犬肿瘤的诊断生物标志物。此外，血浆 DNA 水平升高可能与较短的生存时间有关，cfDNA 浓度可能反映对化疗的反应。