A modified CA-125 progression criterion in ovarian cancer (OC) patients (pts) receiving maintenance treatment following complete clinical response (cCR) to primary therapy

Abstract

5080 Background: CA-125 progression criterion for OC by Vergote et al (JNCI 2000; 92:1534) has been widely adopted, with 35 U/ml as the most commonly used normal limit. Based on recent findings (ASCO Proceedings 2005, #5013), primary therapy cCR OC pts with nadir CA-125 ≤10 versus >10–20 versus >20–35 have different prognosis. We propose to modify the CA-125 progression criterion in this setting as follows: for pts with nadir ≤10, value ≥20 that is confirmed equals progression; for pts with nadir >10, value ≥ 2×nadir that is confirmed equals progression. This new criterion essentially treats 10 U/ml as the normal limit. Methods: The proposed criterion combined with RECIST was tested on SWOG 9701/GOG 178 pts (n = 287) and compared to the existing criterion. All pts achieved cCR from primary therapy and entered the above maintenance trial with CA125 ≤35. Results: Of 91 pts last known to be progression-free by existing criterion, 10 (11%) new progressions were called. Available CA-125 values continued to rise in all except 1 case (1%). For 196 pts with known progressive disease, the progression date was unchanged by the new criterion in 42%, and was earlier by ≤60 days in 31%, 61–180 days in 16% and >180 days in 11% (overall median days early = 56). Conclusions: In a series of 39 primary therapy cCR pts with CA-125 ≤35, Santillan et al found a progressive low-level increase in CA-125 to be strongly predictive of disease recurrence (JCO 2005; 23:9338). Similarly, initial testing of the proposed CA-125 criterion demonstrated a low false positive rate and early detection of disease progression >2 months in approximately 30% of the same first line complete responders with progressive disease during or after maintenance treatment. Such pts can potentially benefit from starting alternative treatments early. The proposed criterion should be further investigated. No significant financial relationships to disclose.