Introduction
Screening colonoscopy reduces colorectal cancer (CRC) mortality. However, several studies have reported a lower participation rate of colonoscopy. Now it is important to provide less invasive test for CRC screening.
AminoIndex® Cancer Risk Screening (AICS®) is an examination that measures plasma amino acid concentrations and estimates the risk of existing CRC based on the difference in amino acid balance in patients with CRC and healthy individuals. AICS is calculated from 0.0 to 10.0 with the higher value indicating a higher the risk of existing CRC.
We aimed to conduct a prospective cohort study to evaluate the accuracy of AICS® in detecting the risk probability for early colorectal lesions, such as advanced adenoma (AA), intramucosal neoplasia (Tis), or T1 CRC.
Aims & Methods
Consecutive patients who underwent colonoscopy between 06/02/2017 and 31/03/2021at the National Cancer Center Central Hospital and endoscopically diagnosed adenoma larger than 20 mm, intramucosal neoplasia (Tis), or submucosal invasive carcinoma (T1) were included as a selection criterion. Patients with endoscopically suspected intramucosal neoplasia or high-grade dysplasia by preoperative colonoscopy, but finally diagnosed with adenoma were also included in the study. We excluded the following patients; 1) patients with polyposis such as familial colorectal adenomatosis or inflammatory bowel disease, 2) patients with concurrent cancer of other organs, 3) patients with obvious bleeding, 4) patients with severe defecation disorder, and 5) patients with stenosis of colon or intestine.
We measured plasma amino acid concentrations calculated the AICS score. FIT was also measured at the same time. The lesions were endoscopically resected using EMR or ESD technique. The sensitivity of AICS, FIT, and the combination of FIT and AICS were examined according to the pathological diagnosis.
Results
Two hundred and seventeen patients were included in the primary analysis, and 208 patients excluding 9 patients who did not perform FIT were included in the secondary analysis.
The median age of the 217 patients was 71 years old (range: 32- 91). The mean lesion size was 28.9 mm±12.9. Prevalence of AA, Tis, T1, and advanced lesion was, 63, 118, 30, and 6, respectively. Six lesions were suspected to be T1 carcinoma on preoperative endoscopy, following pathological examination revealed advanced cancer after endoscopic resection. The sensitivity of AICS for the advanced neoplasia (AN), AA, intramucosal neoplasia (Tis), submucosal invasive carcinoma, and advanced CRC was 28.1％, 30.9%, 25.4%, 23.3%, and 33.3%, respectively.
In the secondary endpoint, the sensitivity of FIT for AN, AA, intramucosal neoplasia (Tis), submucosal invasive carcinoma, and advanced CRC was 47.0%, 35.3%, 49.1%, 46.7%, and 100%, respectively. The sensitivity of the combination of FIT and AICS for AN, AA, intramucosal neoplasia (Tis), submucosal invasive carcinoma, and advanced CRC was 61.1％, 52.9%, 64.0%, 60.0%, 100%, respectively.
Conclusion
Although it was a reasonable value compared to the development data, AICS® has insufficient sensitivity for lesions requiring endoscopic intervention. It could be clinically applicable as a minimally invasive examination to stratify the risk of existing CRC in combination with FIT for colorectal screening.
Disclosure
The primary investigator (Hiroyuki Takamaru) had received research funding from Ajinomoto Co. Ltd.