Background
Bowel cancer is the 3rd most commonly diagnosed cancer in Australia and the 2nd leading cause of cancer-related deaths, though early detection can improve survival to 98.6%. Colonoscopy, while effective, is invasive and costly. The current screening test is non-invasive but detects only ~15% of early-stage cancers and has a high false-positive rate. This study proposes a novel, cell-based screening method that targets exfoliated colonic epithelial cells, both dysplastic and cancerous, naturally shed into stool, aiming to improve early detection and accuracy.
Aim
This project aims to develop an optimised stool collection platform that preserves exfoliated colonic epithelial cells for cytological analysis.
Methodology
To optimise a stool processing platform for cytological analysis, firstly, HCT-116 colon cancer cells were used to model exfoliated colonic cells, and later, healthy stool samples were used. Preservation, isolation, and identification methods were tested under varying time and temperature conditions. Cells were stored in PBS (control), alcohol-based preservatives with a bacteriostatic buffer, then processed using serial filtration and density gradient centrifugation. The data collected were cell counts obtained using a haemocytometer, their morphology was assessed with Papanicolaou staining, and analysed through Likert scoring, multiple T-tests, and one-way ANOVA.
Results
Cells were successfully preserved in alcohol-based preservatives, with significantly greater stability at 4 °C compared to room temperature. Preservation time influenced morphology, though the optimal duration requires further testing. Density gradient separation consistently achieved superior recovery of HCT-116 colon cancer cells and healthy stool epithelial cells, and effectively distinguished healthy stool-derived cells from bacteria and debris.
Conclusion
This study demonstrates the feasibility of preserving and isolating exfoliated colonic cells from stool with high integrity, supporting the potential of a cytology-based stool screening platform. Further optimisation of preservation times and cytomorphological characteristics for downstream analysis, such as immunocytochemistry, will be essential for translating this approach into clinical bowel cancer screening.