Predictive value of serial CA 125 antigen levels in ovarian cancer evaluated by second-look laparotomy

Serial serum CA 125 levels were measured before definitive surgery and during chemotherapy for 12 months or more in 64 patients with ovarian cancer. In the 42 patients who had a complete clinical remission and thus were subjected to a second-look laparotomy, an absence of disease was not predicted by patterns of CA 125 levels. Whilst rising or persistently high levels indicated the presence of tumour in 92% of patients, declining levels to negative predicted the absence of tumour in only 50%. Although the majority of these patients showed microscopic foci or a tumour mass less than 1 cm, 3 patients had a larger amount of disease. In the follow-up of 49 patients, the accuracy of prediction of a good outcome was better than that of a poor outcome on the basis of CA 125 patterns, with rates of 92% and 79%, respectively. Our findings indicate that CA 125 lacks sensitivity in detecting small tumour masses (less than 1 cm dia.) but rising or persistently high levels suggest a strong likelihood of a residual tumour to be found at a second-look laparotomy.