Purpose: To evaluate the risk of epithelial ovarian cancer (EOC) recurrence in patients with rising serum cancer antigen 125 (CA-125) levels that remain below the upper limit of normal (< 35 U/mL).
Patients and methods: All patients treated for EOC between September 1997 and March 2003 were identified and screened retrospectively for the following: (1) elevated serum CA-125 at time of diagnosis, (2) complete clinical and radiographic response (CR) to initial treatment with normalization of serum CA-125, (3) at least three serial serum CA-125 determinations that remained within the normal range, and (4) clinical and/or radiographic determination of disease status at the time of last follow-up or recurrence. For statistical analyses, univariate regression models were used to compare absolute and relative changes in CA-125 levels among patients with recurrent disease and those without EOC recurrence.
Results: A total of 39 patients satisfied study inclusion criteria; 22 patients manifested EOC recurrence at a median interval from complete response of 11 months. The median follow-up time from complete response to last contact was 32 months for the 17 patients in the no recurrence group. A relative increase in CA-125 of 100% (odds ratio [OR] = 23.7; 95% CI, 2.9 to 192.5; P = .003) was significantly predictive of recurrence. From baseline CA-125 nadir levels, an absolute increase in CA-125 of 5 U/mL (OR = 8.4; 95% CI, 2.2 to 32.6; P = .002) and 10 U/mL (OR = 71.2; 95% CI, 4.8 to > 999.9; P = .002) were also significantly associated with the likelihood of concurrent disease recurrence.
Conclusion: Among patients with EOC in complete clinical remission, a progressive low-level increase in serum CA-125 levels is strongly predictive of disease recurrence.