Background & objective: It was indicated that there was relationship between estrogen and colorectal cancer. Estrogen receptor (ER) and progesterone receptor (PR) were expressed in colorectal cancer tissue. They were measured using immunohistochemistry with various results,but there was little quantitative study. This study was designed to quantitatively measure the expression of ER and PR in tumor tissues and normal mucosas and analyze its relationship with clinicopathological parameters in colorectal cancer.
Methods: ER and PR expression in cytoplasm and nucleus of tumor tissues and normal mucosas from 45 colorectal cancer patients were quantitatively measured using radioligand binding assay (RBA).
Results: ER and PR were expressed in all tumor tissues and normal mucosas. In cytoplasm, the ER expression level of tumor tissues was higher than that of normal mucosas; they were 7.96+/-3.69 fmol/mg protein and 4.34+/-2.84 fmol/mg protein (P< 0.01) respectively. And that was the same for PR expression; they were 3.89+/-2.64 fmol/mg protein and 2.50+/-1.73 fmol/mg protein(P< 0.01)respectively. In nucleus, the ER expression level of tumor tissues was higher than that of normal mucosas; they were 18.42+/-8.30 fmol/mg protein and 11.24+/-5.44 fmol/mg protein (P< 0.01)respectively. And that was the same for PR expression, they were 9.36+/-5.90 fmol/mg protein and 7.84+/-7.41 fmol/mg protein (P< 0.05) respectively. There was positive correlation between ER and PR expression in cytoplasm and nucleus of tumor tissues (P< 0.01) respectively,so was in cytoplasm in normal mucosas (P< 0.01) respectively, but not in nucleus (P >0.05). There was correlation between ER expression in tumor tissues and patients' age,and the expression in these people over 45 years old was higher than those less 45 years old (P< 0.05), but no correlation between tumor tissues PR expression and age (P >0.05). There was no correlation between tumor tissues ER, PR expression and sex, staging, tumor location, size, gross and histological type, invasive depth, lymph nodes metastasis, or tumor tissue CEA expression (P >0.05).
Conclusions: ER and PR expression in colorectal tumor tissues were higher than those in normal mucosas, and there was positive correlation between ER and PR expression in tumor tissues. All these indicate that ER in colorectal cancer tissues has some activity. The level of the ER, PR expression in tumor tissue could not predict the malignant biological behaviors of colorectal cancer.