San Diego, CA, May 21, 2016—Even a delay of 6 months for follow-up colonoscopy after a positive fecal immunochemical test (FIT) may result in a higher risk for colorectal cancer (CRC)-related outcomes, and this risk increases as the time to follow-up colonoscopy increases, according to research presented here at Digestive Disease Week 2016.
“One of the questions in doing colon cancer screening is, if someone has a positive test, how long is the optimal time to do the follow-up exam. If there is some harm that comes from having to be able to wait for a while, then we want to be able to make sure that the time is as short as possible. On the other hand, if short periods of waiting are not harmful, that gives the patient as well as the health care system some additional flexibility in terms of when to be able to schedule the time,” said lead researcher Douglas Corley, MD, PhD, MPH, gastroenterologist, and research scientist at the Division of Research, Kaiser Permanente, San Francisco, CA.
Dr. Corley and colleagues conducted this retrospective study to assess variations in time to colonoscopy follow-up and risk of colorectal cancer-related outcomes after FIT. They included 82,887 patients (average age: 61.2±7.3 years; 52.6% male; 86.2% with completed diagnostic colonoscopy) enrolled in the Kaiser Permanente Northern California (KPNC; through July 2013) and Southern California (KPSC; between January 2010 and October 2012) health plans who were aged 50 to 75 years and had a positive FIT (≥ 20 µg Hgb/g).
Via electronic medical records, they obtained and recorded patients’ time to colonoscopy after positive FIT, CRC diagnoses, and stage, and any potential confounders. Using multivariate logistic regression, they evaluated time to colonoscopy (8 to 30 days [reference group], 31 to 60 days, 61 to 90 days, 91 to 180 days, 181 to 364 days, and ≥ 365 days after positive FIT), risk of CRC, advanced-stage CRC, and CRC by stage.
Dr. Corley and colleagues excluded those patients in whom exams were performed within 7 days of testing, and adjusted for sex, age, race and ethnicity, BMI, Charlson comorbidity score, region, FIT screening year, and previous FIT screening (ever, past year).
In these patients, median time to colonoscopy was 37 days, and 64.1% of patients underwent colonoscopy within 60 days, 74.6% within 90 days, 80.9% within 180 days, and 83.4% within 12 months. Researchers found that patients who underwent colonoscopy within 6 to 12 months were more likely to be diagnosed with CRC compared with those with follow-up within 30 days (adjusted odds ratio [OR]: 1.29, 95% CI: 1.02, 1.62) and stage II CRC (OR: 1.98, 95% CI: 1.28, 3.06).
In addition, patients who had their exams more than 12 months later demonstrated increases in almost all CRC-related outcomes, and these included CRC (OR: 2.20; CI 1.83, 2.65), advanced-stage CRC (OR: 3.17; CI: 2.37, 4.25), stage II CRC (OR: 2.67; CI: 1.85-3.87), stage III CRC (OR: 2.64; CI: 1.87, 3.72), and stage IV CRC (OR: 4.27; CI: 2.48, 7.35).
“If you’re operating a FIT program, or if you’re talking with patients and they want to know, ‘Can I wait a little while until after I have this exam done?’, the main message is, it’s probably ok to wait a little while, but I wouldn’t wait too long. For guidelines or groups that are putting together large programs, the goal would be to have people in no later than 6 months, but there may be some groups who may be at high risk in 3 months,” concluded Dr. Corley.
The primary funding source for this study was the Population-based Research Optimizing Screening through Personalized Regimens (PROSPR) consortium.