Biomarkers of progestin therapy resistance and endometrial hyperplasia progression.

OBJECTIVE: We sought to identify biomarkers associated with progestin therapy resistance and persistence/progression of endometrial hyperplasia. STUDY DESIGN: We performed a nested case-control study among women with complex (n = 73) and atypical (n = 41) hyperplasia treated with oral progestin, followed up 2-6 months for persistence/progression. We evaluated index endometrial protein expression for progesterone receptor isoform A, progesterone receptor isoform B (PRB), PTEN, Pax-2, and Bcl-2. Odds ratios and 95% confidence intervals (CIs) were estimated. RESULTS: Among women with atypical hyperplasia, high PRB expression was associated with 90% decreased risk of persistence/progression (95% CI, 0.01-0.8). High expression of progesterone receptor A and PRB suggested decreased risk of persistence/progression (odds ratio, 0.1; 95% CI, 0.02-1.0). These findings were not observed among women with complex hyperplasia. No associations were found with PTEN, Pax-2, and Bcl-2 protein expression. CONCLUSION: PRB expression shows promise as a biomarker of progestin response. Further research is warranted to understand how PRB expression may guide treatment decisions.

PAX2 loss by immunohistochemistry occurs early and often in endometrial hyperplasia.

Immunohistochemical markers to assist in the diagnosis and classification of hyperplastic endometrial epithelial proliferations would be of diagnostic use. To examine the possible use of PAX2 as a marker of hyperplastic endometrium, cases of normal endometrium, simple and complex hyperplasia without atypia, atypical hyperplasia, and International Federation of Gynecology and Obstetrics (FIGO) grade 1 endometrioid carcinomas were stained for PAX2. Two hundred and six endometrial samples were available for interpretation of PAX2 staining. The percentage of cases with complete PAX2 loss (0% of cells staining) increased with increasing severity of hyperplasia: 0% of normal proliferative and secretory endometrium (n=28), 17.4% of simple hyperplasia (n=23), 59.0% of complex hyperplasia (n=83), 74.1% of atypical hyperplasia (n=54), and 73.3% of FIGO grade 1 endometrioid cancers (n=15). Partial loss of PAX2 expression did occur in normal endometrium (17.9%) but in smaller proportions of tissue and was less frequent than in simple hyperplasia (47.8% with partial loss), complex hyperplasia (32.5%), atypical hyperplasia (22.2%), and FIGO grade 1 carcinomas (20.0%). Uniform PAX2 expression was rare in complex (8.4%) and atypical hyperplasia (3.7%) and carcinoma (6.7%). When evaluating loss of PAX2 in histologically normal endometrium adjacent to lesional endometrium in a given case, statistically significant differences in staining were observed for simple hyperplasia (P=0.011), complex hyperplasia (P<0.001), atypical hyperplasia (P<0.001), and FIGO grade 1 endometrioid cancer (P=0.003). In summary, PAX2 loss seems to occur early in the development of endometrial precancers and may prove useful in some settings as a diagnostic marker in determining normal endometrium from complex and atypical hyperplasia and low-grade carcinomas. However, it is not useful in distinguishing between these diagnostic categories.

Diagnosing endometrial hyperplasia: why is it so difficult to agree?

Current World Health Organization classification of endometrial hyperplasia is problematic because of poor diagnostic reproducibility. We sought to determine factors that cause diagnostic disagreement in a review of 2601 endometrial specimens. Blinded random specimens of normal endometrium, hyperplasias, and carcinoma were reviewed by 2 pathologists, with review by a third pathologist in cases with disagreement. All cases of endometrial hyperplasia or carcinoma were scored for degree of glandular crowding, architectural complexity, and cytologic atypia. Sample adequacy, hyperplasia volume, presence of metaplasia, or endometrial polyp were also scored. The overall kappa for agreement was 0.71, with a lower kappa of 0.36 when cases called "no hyperplasia" were excluded. The percent specific agreement was 90.3% for no hyperplasia, 31.1% for simple hyperplasia, 51.1% for complex hyperplasia, 49.8% for atypical hyperplasia, and 57.5% for adenocarcinoma. Cases categorized as "low volume hyperplasia" had more diagnostic disagreement than "high volume," (62% vs. 39%, P=0.003). Similarly, cases called "scant" had more diagnostic disagreement than "not scant" (65% vs. 57%, P=0.013). The histologic feature associated with the most diagnostic disagreement was cytologic atypia (P<0.0001). Architectural crowding, architectural complexity, or the presence of a polyp were all associated with diagnostic disagreement (P<0.0001). High diagnostic disagreement in endometrial hyperplasia is related to both sample adequacy and interpretation of histologic features present. Although obtaining additional tissue may increase diagnostic reproducibility, differences in interpretation of key histologic features like cytologic atypia remain major factors contributing to diagnostic disagreement.