Fecal immunochemical tests for surveillance of the colorectal neoplasia after polypectomy

Abstract

The incidence and mortality related to colorectal cancer (CRC) were rising in Asia [1]. The detection and removal of precancerous lesions through CRC screening with colonoscopy can reduce the CRC incidence and mortality [2]. Patients who have colon neoplasia are at increased risk for developing metachronous neoplasia or cancer. As a result, post polypectomy surveillance with colonoscopy is recommended for those patients with a personal history of colorectal neoplasia [3,4]. However, there is significant debate over the recommended interval between colonoscopies within surveillance programs. The American Polyp Study has demonstrated that post polypectomy colonoscopy at one or three years interval has a similar yield, leading to recommendations that post polypectomy colonoscopy can be delayed for 3-5 years, depending on histology [5]. The National Health and Medical Research Council of Australia (NHMRC) recommends post polypectomy surveillance intervals as following: (1) within a year following incomplete or inadequate examination, (2) three years for subjects with CRC or advanced adenoma (i.e., size ≧ 10 mm, high grade dysplasia, villous change, or 3 or more adenomas), and (3) 5 years in the remainder for those with a personal history of colorectal adenomas or cancer [4]. Nevertheless, in clinical practice, actual intervals vary widely and colonoscopy is often performed more frequently than these recommendation, presumably due to the concerns of the following: (1) the reliability of surveillance procedures and the consequences of delay in detection of missed lesions until the next scheduled colonoscopy, (2) the possibility of rapidly progressive lesions that might develop in the years between scheduled colonoscopies [6]. A guideline has raised concern about colonoscopy quality and missed lesions [7]. Overall miss rates for neoplastic polyps in the literature range from 8% to 24%, the miss rates being higher for polyps smaller than 10 mm and polyps located at the splenic or hepatic flexure or at the cecum [8,9]. It is also reported that neoplastic lesions of the proximal colon may biologically differ from distal lesions and progress to malignancy with a short dwell time [10]. One possible strategy to aid detection of missed or rapidly developing neoplasms and give added reassurance to both clinician and the person under surveillance is to undertake annual fecal immunochemical tests (FIT) in the interval between surveillance colonoscopies [7]. The FIT uses antibodies specific to human hemoglobin, albumin, or other blood components which is more specific for human blood and less prone to false positive tests related to diet than guaiac fecal occult blood test (gFOBT). Skaife, et al performed FIT on samples obtained on digital rectal examination, prior to planned colonoscopy, in patients in a surveillance program because of a past history of CRC [11]. In 611 patients there was a 9.7% positivity rate, with nine cancers being detected in the FIT positive group and none in those who were FIT negative. In four cases the cancer was a local recurrence and in five it was a metachronous cancer. Bampton, et al found that a one off FIT within a colonoscopy based surveillance program had a participation rate of nearly 50% and appeared to detect additional pathology with 6 cancers and 8 advanced adenomas, especially in patients with a past history of colonic neoplasia [12]. In a colonoscopic surveillance program, a much larger study conducted by Lane, et al found that interval FIT in a colonoscopic surveillance program speeds detection of colorectal neoplasia [13]. The diagnosis of cancer was made 25 months (median) earlier and diagnosis of advanced adenoma 24 months earlier [13]. Moreover, patients who had repeated negative results from FIT had an almost 2-fold decrease in risk for CRC and advanced adenoma compared with patients who were not tested. However, there is still insufficient evidence to make a recommendation if FIT test should be performed in the following 3-5 years after colonoscopy [10]. If the patients do have an interval-positive FIT, the clinician's judgment to repeat colonoscopy could consider the prior colonoscopy findings, completeness of examination, bowel preparation, and family history [10]. Recently, a large retrospective cohort study reported that not only the FIT positivity rate but also the adenoma detection rate was significantly higher in the post-polypectomy surveillance group compared with the repeated screening group [14]. The authors concluded that FIT may play a role for post-polypectomy surveillance. Post-polypectomy surveillance via annual or biennial FIT might offer a more cost-effective way when compared with earlier and more frequent colonoscopic surveillance because colonoscopy is expensive, carries an incidence of morbidity. In addition, frequent colonoscopic surveillance will be intolerable for patients and over-stretches the health system. One issue waiting to be resolved is whether interval FIT repeated at annual or other intervals indeed give a further increase in the yield. Another uncertain issue is whether the additional pathology detected by incorporating FIT into colonoscopy implies lesions missed at the prior colonoscopy which have rapidly progressed in the interval. In conclusion, FITs could be considered in the interval between surveillance colonoscopies, particularly in those patients with colon polypectomy during CRC screening because of a higher yield for additional pathology. Further prospective large-scale randomized studies will be needed to determine the practicality and the cost-effectiveness of FIT for post-polypectomy surveillance. The author declares no conflicts of interest.