Ratio of concentrations of estrogen receptors to progesterone receptors (ER/PR) in the cytosol of breast cancers (stratification by forming of groups differing in PR).

The ratio of cytosol concentrations of estrogen receptors to progesterone receptors (ER/PR) can help at the diagnosis of the excessive production of estrogens or (on the contrary) of the lowered function of ER or of the too small expression of the PR gene. We divided the statistical set into the groups with the approximately same concentrations of PR for stronger judgement of this ratio because PR is nearly not changing due to the age (in contrast to the age unstable ER). We used this stratification into the PR-limited groups at the radio-receptor analysis of 147 patients. 1) The ER/PR quotient was higher in the older patients but predominantly it was approximately 10-times lower in case of the high PR than in case of the low PR. This is why the more than 10-fould error can arise at uncorrected judgement whether ER of some patient is inadequately high or low in the comparison with her PR. It implies that e.g. in case of any one patient it is possible to infer the excessive production of ER from the comparison of her ER/PR--best only in the range of her PR-limited group (and in the addition taking account of the age). It can be important for therapy and prognosis. 2) The interpersonal differences of ER and ER/PR were approximately 10-times smaller in PR-limited groups than in the whole statistical set. This is why e.g. the correlation coefficients of the age increase of ER and ER/PR in the PR-limited groups were more favourable than in the whole non-stratified statistical set. In case if PR decreases in the higher age in case of some authors, it is necessary to create the PR-limited groups by another manner. For instance, 20 % of the tumors with the highest PR from each age group will be in the same PR-limited group (despite the fact that they differ in PR). The impact of the age will be then more marked in case of ER/PR than in case of ER only because the numerator elevates and denominator decreases. The impact of the ovarian cycle might be detected more sensitively on the same principle. It is possible to analyse by this manner the possibility to transform the receptor results to the average age or to the optimal phase of the ovulation cycle to prevent e.g. the false negativity of ER. The principles of this mathematical approach might be exploited even for a judgement of the prognosis and therapy on the basis of the mutual ratio of different isotypes of receptors for one hormone only (ERalpha / ERbeta or PRA / PRB). It concerns not only the breast cancers but also the cancers of the uterus.