EPIDEMIOLOGIC USE OF RECTAL PROLIFERATION MEASURES

Measures of rectal mucosal proliferation have been developed and used in research clinical settings, but their utility for larger-scale epid emiological studies remains uncertain. We assessed the suitability of bromodeoxyuridine (BrdUrd) and proliferating cell nuclear antigen (PCN A)-labeling indices (LIs) in the setting of a multicenter clinical tri al of adenoma recurrence. Subjects at participating practices were ask ed to permit biopsy of normal rectal mucosa during a colonoscopy sched uled for other reasons. PCNA and BrdUrd labeling was performed, and co rresponding LIs were computed. In general, subjects were willing to un dergo biopsy during their scheduled procedures; less than 10% refused. Specimen preparationfor PCNA was acceptable; the mean number of scora ble crypts (+/- SE) was 12.99 +/- 0.37. Preparation for BrdUrd labelin g was less successful, with a higher proportion of unscorable specimen s and a lower mean number of scorable crypts. Among the 54 specimens w ith both LIs computed, the LI for PCNA was modestly higher than that f or BrdUrd LI (4.1 +/- 0.2 and 3.7 +/- 0.2 respectively; P = 0.03). The rank order correlation between the two indices was 0.38. There was va riation across centers in the PCNA LIs but few differences according t o number of crypts scored. Measurement of rectal mucosal proliferation is feasible among endoscopy patients in large studies if PCNA is used ; BrdUrd seems more difficult. The relationship between these two labe ls requires further study.