CA 125 – Tumor Marker
0-35 U / ml
The CA 125 is a high molecular weight glycoprotein (> 200KD), which is highly expressed on the cell surface of coelomic epithelium during embryonic development and in epithelial cells of many ovarian malignancies.
High concentrations in serum CA 125 can be found in the 80% of women with ovarian carcinoma, in 26% of women with benign ovarian tumors and in 66% of patients with non-neoplastic conditions including states like the first trimester of pregnancy, menstruation, endometriosis, adenomyosis, uterine fibrosis, acute salpingitis, liver diseases such as cirrhosis and inflammation of the peritoneum, pleura and pericardium.
Only 0.8% to 3% of women “healthy” have elevated levels of CA 125 between 35 and 65 U / ml. Elevated levels have also been described in patients with pelvic peritoneal tuberculosis.
Elevated levels of CA 125 in the serum (> 35 U / ml) was found in 90% of patients with disseminated ovarian carcinoma (stages II, III and IV), however only 50% of patients only have disease confined to the ovary (stage I) give high levels.
The combination of pelvic examination and concentration of CA 125 (> 30 U / ml) for detection of ovarian cancer give a specificity of 99.6%. In the detection of ovarian cancer, performing ultrasound helps in sensitivity and specificity, likewise, serial determinations of CA-125 values are persistently high positive predictive value.
The absence of a pelvic mass malignant disease is rare, from this point of view, an ultrasound in women with a family history of ovarian cancer when the concentration of CA 125 is above 20 U / ml is a good parameter for the detection of cancer.
CA-125 can also serve as a prognostic marker of survival of the patient. Patients with CA 125 concentrations> 450 U / ml have a poor survival with just seven months, while patients with concentrations 35 U / ml 87%,> 65 U / ml 30%).
The rate of decrease in CA 125 after the first cycle of chemotherapy is a prognostic indicator predictive of patient survival. Patients with> 50% decrease in the concentration of CA 125 have a 45% survival at 2 years compared to 22% in patients whose reduction was <50%. An increase of more than 60 U / ml after the first cycle of chemotherapy is an indication that there may be a relapse.
The most important use of CA 125 is in monitoring patients who underwent oophorectomy. Residual disease were detected in 95% of cases in those patients whose levels of CA 125 were higher than 35 U / ml.
However, a negative result does not exclude the presence of a relapse, half of the patients who had a negative result had microscopic residual carcinoma. The best monitoring of patients with recurrent ovarian carcinoma is the combination of the two procedures, biopsies and CA 125.