A Customized At-Home Stool Collection Protocol for Use in Microbiome Studies Conducted in Cancer Patient Populations

Abstract

Fecal specimen collection in the clinical setting is often unfeasible for large population studies, especially because cancer patients on immunotherapy often experience constipation. A method for constructing and using an at-home stool collection kit designed for epidemiological studies in cancer patients is presented. Participation and compliance rates of the collection kit among late-stage cancer patients from an ongoing, longitudinal study are also discussed. The kit includes three different media on which samples are introduced. Using one stool sample, patients collect specimens by smearing stool onto a fecal occult blood test (FOBT) card, containing three slides for collection. Additional specimens from the same stool sample are added to one tube containing 8 mL of RNAlater preservative and one tube containing 8 mL of 95% ethanol. Stool specimens are stored at room temperature and returned to researchers within 3 days of collection. The purpose of this kit is to yield stool specimens on a variety of media that can be preserved for extended periods of time at room temperature and are compatible with multi-omics approaches for specimen analysis. According to leading microbiome researchers and published literature, each collection method is considered optimal for use in large epidemiological studies. Moreover, the kit is comprised of various components that make stool collection easy, so as not to burden the patient and hence maximize overall compliance. Use of this kit in a study of late-stage lung cancer patients had a participation rate of 83% and baseline compliance rate of 58%.

Keywords: Ethanol; FOBT card; Microbiome; RNAlater; Stool collection.

Fig. 1

Photographs of the disassembled and assembled at-home stool collection kit. In panel a, the three collection media (FOBT card with three collection slides, ethanol, and RNAlater filled tubes) are displayed, along with additional devices, such as gloves and the Protocult collection device, that patients use to collect fecal specimens at home. Panel b depicts the completed kit; upon assembly, the kit should resemble the image above. The ethanol and RNAlater tubes should be standing upright. At this stage, the kit is ready for delivery to patients

Fig. 2

Study participation among late-stage cancer patients in an ongoing, longitudinal study, January 1, 2018—August 31, 2018