Breast core biopsy reporting categories--An internal validation in a series of 3054 consecutive lesions.

We reviewed 3226 consecutive core biopsies (CBs) of 3054 mammographically detected breast lesions performed at our Centre from November 1993 to June 2003. CB diagnoses, classified according to the Non-operative Diagnosis Subgroup of the British National Health Service Breast Cancer Screening Programme (NHSBSP), were B5 (37.1%), B4 (0.5%), B3 (7.6%), B2 (50.9%) and B1 (3.9%). It was necessary to repeat the procedure in 172 cases (5.3%). The values for absolute sensitivity and specificity are 90.8% and 83.8%, respectively. The positive predictive value for categories B4 and B5 is 100%, with no false-positives. The positive predictive value for category B3 is 16.3%. The negative predictive value for B2 category is 97.2%, with a false-negative rate of 3.5%. In conclusion, this system of analysis has enabled us to confirm that our CB results surpass the minimum recommended standards proposed by the NHSBSP.

Standardized approach for microsatellite instability detection in gastric carcinomas.

Microsatellite instability (MSI) defines a specific type of genetic instability. Although consensus diagnostic criteria for MSI definition in colorectal cancer have been established, their utility in other tumor types remain to be proven. Previously we developed a mathematical model for MSI definition in colorectal cancer. The aim of this study was to establish diagnostic criteria for MSI evaluation in human gastric cancer. We designed an algorithm for the efficient characterization of MSI and used it to analyze data on 7 microsatellite markers in 35 gastric carcinomas. Theoretical models considering 1, 2, or 3 populations were tested against the data collected. Also, hypermethylation of hMLH1 gene promoter and hMLH1 protein expression were studied. The observed frequencies of MSI in our series of samples best fit a 2-population model: stable and unstable, defined by instability in 2 or more of a minimum of 7 markers analyzed. MSI was observed in 29% of the tumors. Misclassification rate was <4% when any 7 loci were analyzed. MSI(+) tumors inversely associated with p53 protein overexpression. A good correlation between hMLH1 status (either protein or promoter hypermethylation) and MSI classification was observed. We have developed a simple, sensitive, and specific approach to assess the presence of MSI in gastric cancer that may have clinical applications.