晚期胃肠道肿瘤患者血浆游离DNA片段的检测、定量

The study of quantify and detection and clinical significance of plasma free-DNA part of the gastrie cancer and colorectal cancer patients

目的探讨肿瘤患者循环血液中DNA改变，及对提高肿瘤患者治愈率和生存率的临床实际意义。方法随机采集了2004年10月-12月大连医科大学附属二院经病理确诊的初治晚期胃、大肠癌患者的血标本18份，门诊健康体检者血标本16份，通过酚／氯仿提取法定量检测两组的血浆DNA片段，进行对照比较，分析健康人与晚期胃肠道肿瘤患者血浆游离DNA片段水平的差异、晚期胃肠道肿瘤患者血浆游离DNA片段水平与预后相关指标的相关性。结果晚期胃肠道肿瘤组血浆游离DNA片段水平高于正常健康对照组，其血浆游离DNA片段的均值分别为（346．3±81．62）μg/ml与（27．6±6．91）μg／ml．差异有显著性；胃癌、大肠癌患者两组间的血浆游离DNA片段差异无显著性，均值分别为：（350．8±110．92）μg／ml与（357．1±126．26）μg/ml；在预后相关指标的各因素中，晚期胃肠道肿瘤患者的血浆游离DNA片段水平与免疫状态、是否存在远处转移有明显相关性，其中与免疫状态呈负相关，与远处转移呈正相关。结论晚期胃肠道肿瘤患者血中的游离DNA片段水平较健康人高，可能与患者自身状态、病理分型、疾病状态有关；游离DNA片段可以作为检测晚期胃肠道肿瘤的特异性指标，还可以替代免疫状态及是否存在远处转移等指标评价远期预后，并有取材方便、检测时间短、可以定量分析的优点，对临床有一定的指导意义和应用价值。

Objective Through detecting the variation of its specific circulating DNA, with might be adopted as an efficient marker concering early diagnosis,judgment on the therapeutic effects and recurrence/metastasis followed -up ,with actual clinical importance to increase curative/survival rate for cancer patients. Methods In this research 18 blood samples were randomly collected from advaced gastric/colorectal cancer patients under their primary treatment and diagnosed by Pathology Department of 2nd Affiliated Hospital of Dalian Medical University from October to December 2004,together with 16 samples from healthy volunteers under physical examination at the Out-Patient Department. Hydroxybenzence/chloroform extration was adopted to carry out quantitative detection on plasma DNA fragment of the 2 groups, then comparative analysis was carried out to study the correlation between plasma DNA fragment level and various inner group factors of gastric/colorectal cancer patients, such as immunity, presence of metastasis. Results The level of plasma DNA fragments in gastric/colorectal cancer group was higher than that in control with significant difference （346.3 ±81.62） μg/ml vs （27.6 ±6.91 ） μg/ml. Significant difference also existed between gastric and colorectal cancer group concerning level of plasma DNA fragments （350. 8 ± 110.92） μg/ml vs （357. 1± 126.26） μg/ml. Prognosis analysis suggested that the level of plasma DNA fragments significantly correlated to the immunity ,presence of distant metastasis in gastric/colorectal patients ,with negative correlation to immunity condition,and positive correlation distant metastasis. Conclusions The above resuhs suggest that the level of circulating DNA fragments in gastric/colorectal cancer patients was higher than that in healthy persons, with variation between different stages, which might be associated with general condition, pathology and disease state of the patients;circulating DNA fragments maybe adopted as a specific marker to diagnose gastric/colorectal cancer,or as a substitution for immunity, presence of metastasis to evalute further prognosis. With advantages such as easier sampling, shorter examination and quantitative analysis ,circulating DNA was of guidance signification and application value in clinical oncology concerning the treatment on gastrie/colorectal cancer.