Estrogen receptor status, determined by immunohistochemistry, as a predictor of the recurrence of stage I endometrial carcinoma

BACKGROUND. The aim of this study was to compare the concordance between im munohistochemical (IHC) and biochemical (RIA) methods for determining hormo ne receptor status in patients with endometrial carcinoma and to determine whether IHC expression of estrogen and progesterone receptors (ER and PR) h as prognostic significance. METHODS. Paraffin blocks were obtained from patients diagnosed with endomet rial carcinoma between 1987 and 1991. IHC analysis for ER and PR expression was performed and scored based on staining intensity and the percentage of tumor cells with nuclear staining. Biochemical assays were performed on fr ozen tissues. Concordance between the two methods was evaluated and hormone receptor status was correlated with tumor grade, stage, recurrence and sur vival. RESULTS, ER and PR expression, determined by IHC, correlated well with RIA levels (Spearmans correlation coefficient, P = 0.006 and 0.0005, respective ly). Determination of ER and PR expression by bath methods was correlated w ith tumor grade. Hazards ratios revealed that the absence of ER and PR expr ession, determined by both IHC and RIA, independently correlated with recur rence in early stage disease (P < 0.05). CONCLUSIONS. Historically, receptors have been determined by RIA. In this s tudy, IHC and RIA were equally suitable for determination of ER and PR. Thi s is significant clinically as IHC has several advantages over RIA, includi ng easier processing, lower cost, greater speed, and applicability to fixed tissue samples. In addition, ER negative status was predictive of the recu rrence of Stage I tumors independent of tumor grade. ER status may aid the clinician in planning treatment when adjuvant treatment is controversial. C ancer 1999;86:2083-9. (C) 1999 American Cancer Society.