Effect of the environment on home-based self-sampling kits for anal cancer screening

Background: Anal cancer incidence has increased in Western countries in recent decades and currently there are no consensus screening guidelines. Home-based self-sampling kits might facilitate screening for anal precancer/cancer but could require travel through postal mail where they may experience extreme temperatures or long transport times. Objective: To determine the effect of the environment on specimen adequacy for HPV genotyping of a mailed home-based self-sampling anal cancer screening kit. Study design: The Prevent Anal Cancer (PAC) Study in Milwaukee, Wisconsin recruited men who have sex with men (MSM) and transgender persons 25 years of age and older. Participants were randomized to receive a mailed self-sampling kit or attend a clinic for screening. Kits were insulated with foam and included a device to record temperature every twenty minutes. Samples were returned via mail and underwent HPV genotyping using the SPF₁₀-LiPA₂₅ assay which also detected human RNase P to determine specimen adequacy by qPCR. For the first 93 kits, logistic regression assessed associations between specimen inadequacy and temperature, freeze-thaw cycle, presence of fecal matter, and number of days in an uncontrolled environment. Results: Most specimens (92.5%) were adequate for HPV genotyping. Specimen inadequacy was not associated with temperature, freeze-thaw cycle, or transit time. Fecal matter was present more often in inadequate (71.4%) compared to adequate specimens (16.3%) (p = .004). Conclusions: These real-world data from mailed home-based anal self-sampling kits found that environmental conditions did not affect specimen adequacy. While over 90% of specimens were adequate, presence of fecal matter predicted specimen inadequacy.