PAS Is Superior to H&E for Screening Prophylactic Gastrectomies from CDH1 Mutation Carriers
AF Lee, H Rees, DA Owen, DG Huntsman. University of British Columbia, Vancouver, BC, Canada; Saskatoon City Hospital, Saskatoon, SK, Canada; Vancouver General Hospital, Vancouver, BC, Canada; British Columbia Cancer Agency, Vancouver, BC, Canada
Background: Hereditary diffuse gastric cancer is an autosomal dominant cancer susceptibility syndrome caused by germline mutations in the E-cadherin (CDH1) gene, with a penetrance of 70%. Because endoscopy can not be relied upon to detect early diffuse gastric cancers, prophylactic gastrectomy is the cancer risk reduction strategy of choice for many unaffected mutation carriers. Examination of the entire mucosa of prophylactic gastrectomy specimens is essential and has revealed occult gastric cancers in >90% of cases. We hypothesized that diagnostic accuracy and speed of microscopic analysis of prophylactic gastrectomy specimens could be improved by staining entire cases with PAS rather than H&E for primary screening.
Design: Formalin-fixed paraffin embedded tissue sections from six total gastrectomy cases, all from molecularly confirmed CDH1 mutation carriers (108-164 blocks per case), were subjected to PAS staining; an alternate level from each block was stained with H&E. PAS and H&E-stained slides for each case were combined and randomized. For each slide, the microscopic presence or absence of invasive signet-ring cells, and the time taken to examine the slide, were recorded by an observer blinded to the original pathologic diagnoses. Lesions present in both PAS and H&E-stained slides on review, but identified only in one slide at primary screening, were scored as missed lesions.
Results: In three gastrectomy specimens examined to date, significantly fewer lesions were missed on PAS-stained slides (5 missed lesions) than on H&E-stained slides (13 missed lesions); p<0.05 by Fisher's exact test. In addition, the average time taken to examine each case was significantly less for the PAS-stained condition (2 hr 50 min +/- 31 min) than for the H&E-stained condition (4hr 18 min +/- 34 min); p<0.05 by Student's t-test.
Conclusions: Our data to date suggest that diagnostic accuracy and speed for detecting invasive signet ring carcinomas in prophylactic total gastrectomies from CDH1 mutation carriers may be improved by performing PAS staining on the entire case instead of H&E.
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 60, Tuesday Afternoon