Cell cycle analysis of colorectal brushings collected in liquid-based cytology.

Objective: To evaluate the possibility of robust cell cycle analysis from liquid-based cytology samples.

Study design: Brushings were obtained after surgical resection of tumor samples. For each patient, one brushing sample was obtained from the macroscopically identified tumor, and a matched sample from a distant normal-appearing site. Cell suspensions were prepared for a time course series of experiments and from formalin-fixed paraffin-embedded tissue samples.

Results: Optimal results could be obtained when the sample was analyzed on the day of collection, whereas cell cycle analysis could be easily performed when cells were stored in a methanol-water solution for < 3 days, with a small penalty on coefficiency of variation (CV) values. Further storage in liquid-based medium had a profound effect on cell cycle analysis. CV values of liquid-based medium out-performed those obtained from samples that were paraffin embedded. Aneuploidy was more common in men and from samples from the left colon. Near diploid cell populations were more common in samples from the right colon.

Conclusion: Liquid-based cytology fixation and preservation media that are methanol-based could serve as an ancillary collection medium, providing cell cycle data for colorectal carcinoma samples.