Rapid and prognostically valid quantification of immunohistochemical reactions by immunohistometry of the most positive tumour focus. A prospective follow-up study on breast cancer using antibodies against MIB-1, PCNA, ER, and PR.

The prognostic significance of immunohistochemical markers for cell proliferation [MIB-1, proliferating cell nuclear antigen (PCNA)] and hormone receptor analysis [oestrogen receptor (ER), progesterone receptor (PR)] was tested by means of immunohistometry in a series of 103 breast cancer patients in comparison with the lymph node status N, the tumour size T, histomorphological grading, and the biochemical ER and PR status. Immunohistochemical reactions were performed on 2 microns sections from paraffin-embedded tissue, using an indirect peroxidase method. The proportion of immunostained tumour cell nuclei was determined using a TV-image analysis system. Measurements were performed using a 20 x objective on 40 viewing fields (1.94 mm2, MIB-1 and PCNA) or 20 viewing fields (0.97 mm2, ER and PR). The mean immunopositivity of all viewing fields and the value of the most immunopositive viewing field (MIB-1max, PCNAmax, PRmax, ERmax) were calculated. The mean values and the maximal values were highly correlated (r = 0.903, P < 0.001). After 1:2:1 quantilization, 84.2 per cent of the 412 single measurements revealed mean and maximal values in the same category (P < 0.0001). For each of the four immunohistochemical markers, the prognostic significance of the maximal values was higher than that of the mean values. The highest prognostic significance was found for MIC-1max (P = 0.0002), followed by PRmax (P = 0.0046), ERmax (P = 0.0154), and PCNAmax (P = 0.0161). From the results of a Cox model, a 'prognostic index (PI)' was developed, ranging from -1 to 8: PI = 2 x N + T + MIB-1max-PRmax. The four groups of patients with PI values of < 2, 2-3, 4-5, and > 5 revealed significantly different 7.5-year survival probabilities (P < 0.0001). The simplicity of the PI makes it a clinically useful, routinely applicable, and understandable parameter in the surgical pathology of breast carcinoma.

Simultaneous immunohistochemical and biochemical hormone receptor assessment in breast cancer provides complementary prognostic information.

The prognostic value of the biochemical and the immunohistochemical assessment of estrogen- and progesterone receptor (ER, PR) status was tested in 111 breast cancer patients, mostly focusing on whether the results reveal complementary prognostic information. The biochemical receptor analysis was performed on snap-frozen tumor tissue using a standard protocol (ER-DCC, PR-DCC). The immunohistochemical staining was done on 4 microns thick paraffin sections and was evaluated semiquantitatively (ER-IHC, PR-IHC) and immunohistometrically by means of image analysis (ERMEAN, PRMEAN). 74% of the ER-DCC and 50% of the PR-DCC assays were interpreted as positive. The positivity rates of the immunohistochemical reactions ranged between 78% and 81% for ER and between 66% and 82% for PR, depending on the interpretation mode. The concordance rate for the DCC method was 68%, and ranged between 77% and 85% for the immunohistochemical results on paraffin sections. ER-DCC and PR-DCC showed a better survival for receptor-positive patients; however, this tendency was only statistically significant for the PR-DCC (p = 0.0294). Patients with immunohistochemically determined ER- or PR-positivity revealed a significantly better survival than receptor-negative patients, the effect being stronger for the progesterone receptor (ER: p = 0.0253, PR: p = 0.0005). Combining the different methods and receptors in a multivariate analysis, we observed that a) ER and PR reveal complementary prognostic information to each other after immunohistochemical determination (p < or = 0.0018) and that, b) complementary prognostic information was also obtainable by comparing the biochemical and the immunohistochemical PR-analysis (p < or = 0.0084); slightly more significant results were obtained for ERMEAN and PRMEAN compared to ER-IHC and PR-IHC. Considering the lymph node status and a combined receptor analysis (PR-DCC, ERMEAN, PRMEAN) as the two strongest prognosticators in multivariate Cox models, the combined receptor analysis was able to discover for each of the three groups of NO- and N1-patients different survival probabilities (p < 0.0001). In conclusion, the ER-DCC appears to be dispensable in all patients. In lymph node-negative patients, the PR-DCC has no outstanding merit, indicating that the neccessity of this method is also controversial. In priamry tumors of lymph node-positive patients, however, all three remaining types of receptor analysis should be evaluated for their therapeutic implications.