Keenan Jacqueline, Aitchison Alan, Leaman Jacquie, Pearson John, Frizelle Frank
Surgery, University of Otago, Christchurch.
Microbiology Manager, Southern Community Laboraties, Christchurch.
N Z Med J. 2019 Aug 30;132(1501):48-56.
To determine if tumour-derived M2-PK is potentially a more accurate biomarker of pre-cancerous bowel lesions in patients who present in primary care with bowel symptoms than the detection of faecal haemoglobin.
Patients requested by their general practitioners (GPs) to provide a stool sample to determine the presence of faecal haemoglobin consented for the same stool samples to be tested for the presence of M2-PK. For comparison M2-PK levels were also measured in stool samples from patients recently identified with colorectal cancer and healthy controls who self-reported no bowel problems at the time of sampling.
M2-PK levels measured in 185 GP-derived samples were comparable to the control cohort (57 healthy controls) and notably lower than those in the 57 patients with CRC (2.6, 3.2 and 18.2U/ml-1, respectively). Sixty-seven of the GP patients were referred for colonoscopy. While 26 of these patients had a positive M2-PK, only 10 were found to have colonic lesions. Conversely, 18 of the 41 patients who had a negative M2-PK were found to have lesions that included one CRC, 13 adenomas and four other polyps. The FIT also failed to identify colonic disease in 19 of 48 patients referred for colonoscopy. There was, however, a significant association between lesions greater than 1cm and a positive FIT (p<0.02) that was not the case with M2-PK. A positive FIT identified one patient in the GP patient cohort subsequently diagnosed with colorectal cancer at follow-up colonoscopy whereas the same stool sample tested negative for M2-PK.
Measurement of faecal M2-PK levels lacks the specificity and sensitivity (and therefore diagnostic accuracy) to identify the individuals who should be progressed for clinical follow-up. Accordingly, M2-PK is not is not a robust biomarker for identifying pre-cancerous bowel lesions in a primary care setting.
确定对于在初级保健机构因肠道症状就诊的患者，肿瘤来源的M2 - PK是否可能是比检测粪便血红蛋白更准确的癌前肠道病变生物标志物。
应全科医生（GP）要求提供粪便样本以确定粪便血红蛋白存在情况的患者，同意对同一粪便样本进行M2 - PK检测。为作比较，还检测了近期确诊为结直肠癌患者的粪便样本以及在采样时自我报告无肠道问题的健康对照者的粪便样本中的M2 - PK水平。
在185份来自GP的样本中测得的M2 - PK水平与对照队列（57名健康对照者）相当，且显著低于57名结直肠癌患者的水平（分别为2.6、3.2和18.2U/ml-1）。67名GP患者被转诊进行结肠镜检查。这些患者中26名M2 - PK呈阳性，但仅10名被发现有结肠病变。相反，41名M2 - PK呈阴性的患者中有18名被发现有病变，包括1例结直肠癌、13例腺瘤和4例其他息肉。在48名被转诊进行结肠镜检查的患者中，有19名患者的粪便免疫化学检测（FIT）也未能识别出结肠疾病。然而，大于1cm的病变与FIT阳性之间存在显著关联（p<0.02），而M2 - PK并非如此。一名GP患者队列中的患者FIT呈阳性，但在后续结肠镜检查中被诊断为结直肠癌，而同一粪便样本的M2 - PK检测为阴性。
检测粪便M2 - PK水平缺乏特异性和敏感性（因此缺乏诊断准确性）来识别应进行临床随访的个体。因此，M2 - PK不是在初级保健环境中识别癌前肠道病变的可靠生物标志物。
