Abstract
In Kobe City’s colorectal cancer screening program, over 60% of the screening participants utilize the mail as a means of returning samples, but it is available only during the winter months from November to March. Having the mail as a return option available year-round may be beneficial in terms of improving the return rate. In this study, the feasibility of mail return during the summer was verified using a stool collection buffer newly developed by Eiken Chemical Co., Ltd. (the new buffer).
A precision study was conducted using the current and new buffers with stool suspensions, and the results were compared. Ten hemoglobin (Hb)-positive stools were collected in sampling bottles containing the current and new buffer, respectively, and assessment of residual reactivity of hemoglobin in fecal immunochemical test was performed for up to 35 days under conditions of 4°C to 43°C. The results showed that the durations of the storage period that mean Hb reactivity was 85% or more with the new buffer were 35 days at 4°C and 25°C, 14 days at 35°C, and 3 days at 43°C. In a mailing test in which the remaining reactivity of Hb was assessed with the samples posted in 10 different locations in the summer, the Hb reactivity in the new buffer solution averaged over 95% when the maximum temperature was 41.3°C and the duration that the temperature was over 30°C was 10.3 hours.
In our storage study, the Hb residual reactivity with the new buffer was over 85% for an average of 14 days at 35°C, and in our mailing study in the summer, it was over 95%. With the new buffer, Hb remained stable even under the harsh summer mailing conditions, suggesting the feasibility of the use of mailing return year-round in the screening program.
