An Immunoreactive Score (IRS) was compared to the Composition Adjusted Receptor Level (CARL) evaluating prognostic significance of estrogen receptor (ER) expression in 61 ovarian cancers after > or = 8 years. CARL of ER allowed for calculating individual risk curves in stage III and IV, Grade 2 and 3, serous ovarian carcinoma after surgical debulking to < or = 2 cm residual and platinum based chemotherapy. In overall analysis and in subsets defined by tumor stage, grade or a combination thereof significant prognostic distinction became possible using a cutoff IRS of 4 vs. 0 or vs. scores < or = 3. This study substantiates ER as a prognostic variable in human ovarian cancer and for the first time establishes the value of an IRS.