Tumor marker CA-125 as an evaluator and response indicator in ovarian cancer: its quantitative correlation with tumor volume.

BACKGROUND: The tumor marker Cancer Antigen 125 (CA 125), though not ovarian cancer specific, is widely used for the evaluation of suspected and under-treated ovarian cancer. Many studies show that serum CA 125 level demonstrates ovarian tumor burden and its response, but they lack quantitative correlation between the two. Instead, they rely on clinical or radiological assessment of gross tumor burden. This study examines ovarian tumor volumes and corresponding serum CA 125 values before and during chemotherapy. MATERIALS/METHODS: [corrected] Ovarian tumor volume was measured by CT scans at pre-chemotherapy and after each cycle of chemotherapy in 15 patients. Blood serum CA 125 was determined on the days of CT scans using a one-step immunoenzymatic assay. RESULTS: There was no statistically significant correlation (r = 0.18, p > 0.05) between ovarian tumor volumes and CA 125 among patients at pre-chemotherapy or any subsequent time. In individual patients, the reduction or increase in tumor volume correlated with the corresponding CA 125 values during chemotherapy in 85% (12 out of 14) of patients. Mean CA 125 halving time was 44.1 days, which correlated with tumor halving time (r = 0.63, p < 0.05). CONCLUSIONS: Values of CA 125 cannot be used for comparison of ovarian tumor mass among patients. However, serial estimation of CA 125 in individuals is fairly reliable in terms of the course of the tumor. CT scan is a more informative response indicator, but it is costly and hence may be supplemented by the easy and economical CA 125 estimation.

Potential of CT-scan based tumor volume as a response indicator in chemotherapy of advanced epithelial ovarian cancer.

BACKGROUND: Response prediction in patients undergoing chemotherapy for ovarian cancer is an important issue, since the cure rate is only about 15-20%. We attempted to develop a semi-empirical model to predict response in individual cases after the first cycle of chemotherapy. MATERIAL/METHODS: This prospective study included 51 cases of advanced ovarian cancer. A method was standardized to estimate ovarian tumor volume accurately from CT scan films. This permits the inclusion of patients who have undergone CT scan elsewhere. Patients underwent 4-6 cycles of chemotherapy and tumor volume was estimated after each cycle. This yielded a tumor regression curve for each patient. RESULTS: Percent reduction in tumor volume after the first chemo-cycle was a significant prognostic factor in multivariate analysis. Depending upon the rate of regression patients could be classified into Fast Regressing FR (n=29) and Moderately Regressing MR (n=16), whereas 6 patients showed Progressive Disease (PD) despite ongoing chemotherapy. The median survivals for the FR, MR and PD groups were 29.3, 18.9 and 8.5 months respectively. We found that 'percent reduction in volume after first chemo-cycle' could categorize a patient as FR/MR/PD correctly in 94.1% of cases. This parameter could also detect 5 out of 6 inherently resistant PD cases, who would otherwise undergo further chemotherapy, since early detection of resistance by clinical monitoring is quite difficult. CONCLUSIONS: An individual patient at risk for shorter survival and with inherent drug resistance can be identified after the first cycle of chemotherapy.