Diagnostic Performance of a Fecal Immunochemical Test-Based Colorectal Cancer Screening Program According to Ambient Temperature and Humidity

Abstract

Hemoglobin degradation can be affected by ambient temperature and humidity. How this modifies the advanced neoplasia detection rate and interval cancer rate remains understudied. We conducted a retrospective study and analyzed the impact of ambient temperature and humidity on the fecal immunochemical test (FIT) positivity rate, detection rate for advanced neoplasia, and interval colorectal cancer (CRC). The results of our study indicated that at >24 degrees C, the positivity rate was lower, whereas the detection rate of the FIT for advanced neoplasia and the interval cancer detection rate were not affected, probably because we have adopted measures to minimize the impact of ambient temperature on FIT sensitivity. Humidity did not affect FIT sensitivity. The results emphasize the importance of organizational efforts on the procedures along the screening process (such as the cold chain) to minimize the effect of seasonal variations in temperature on the positivity rate. Exposure of the fecal immunochemical test (FIT) to different ambient temperatures and humidity is unavoidable in population-based screening programs in Southern European countries, and it could lead to a decrease in target colorectal lesions. The objective was to evaluate the effect of ambient temperature and humidity on the FIT sensitivity in a population-based screening program for colorectal cancer (CRC) using an ecological design. The retrospective cohort included individuals aged 50-69 years who participated in CRC screening (Barcelona) from 2010-2015, and were followed until 2017 to identify interval CRCs. The positivity rate, and detection rates for advanced polyps and CRC were compared according to ambient temperature, humidity, and quarters of the year. A positive FIT was defined as the detection of >= 20 mu g Hb/g in feces. The monthly ambient temperature and humidity were recorded on the day that the FIT was performed. In total, 92,273 FIT results from 53,860 participants were analyzed. The FIT positivity rate was lower at >24 degrees C than at <= 24 degrees C (p = 0.005) but was not affected by humidity. The temperature's impact on positivity did not lead to a decrease in the FIT detection rate for advanced neoplasia or the interval cancer detection rate in a program where the samples were refrigerated until the analysis and screening invitations were discontinued in July and August.