CA-125 Not Concordant With Imaging For Progression in Platinum-Resistant Ovarian Cancer

CA-125 biomarker levels may not detect progressive disease in platinum-resistant ovarian cancer patients

medwireNews: CA-125 measurement is not a reliable method of assessing progressive disease (PD) in patients with platinum-resistant ovarian cancer (PROC), say researchers who found significant discordance with radiological findings.

The team explains that they compared CA-125-defined with what they believe to be the gold standard, RECIST-defined, diagnosis for 218 participants of the AURELIA trial. The CA-125 test was performed no more than 28 days before or 21 days after the RECIST diagnosis of PD.

The results were concordant in just 94 of the women and the rate of concordance did not significantly differ between patients who had been given single-agent chemotherapy alone or alongside bevacizumab, at 42% versus 45%.

Among the 124 patients with discordant results, just 26% had an elevated CA-125 level, albeit below the Gynecologic Cancer InterGroup (GCIG) criteria for a positive result, report Kristina Lindemann, from Oslo University Hospital in Norway, and co-workers.

The researchers could not detect any significant differences in baseline characteristics for the patients whose PD was detected by both CA-125 and RECIST versus RECIST alone. 

But patients whose RECIST-defined PD was detected within 8 weeks of entering the AURELIA trial were significantly less likely to test positive for CA-125 than those whose PD was identified at a later point, with 69% versus 53% not meeting GCIG criteria.

Median overall survival for the patients with concordant PD findings was a comparable 10.1 months versus 9.0 months for those with RECIST-defined PD only.

The team confirmed the inadequacy of CA-125 for detection of PD using a second population of PROC patients who had participated in the CARTAXHY trial of weekly paclitaxel alone or with carboplatin or topotecan.

Of the 86 patients with measurable disease at baseline, 46% had CA-125 levels above the GCIG threshold. However, 54% did not meet these criteria and just 22% of these patients with discordant findings had any CA-125 elevation.

Again, patients with early PD were less likely to have concordant results than those with PD detected later, with GCIG criteria not fulfilled in 85% versus 49%.

Writing in the Annals of Oncology, the researchers advocate for regular imaging for PROC patients but, acknowledging that this is not always feasible, suggest research should focus on determining the relationship between RECIST-defined PD and patient-reported benefits for treatments under investigation.

“We also strongly advocate the inclusion of patient-reported outcomes as an end point in future clinical trials in PROC”, they emphasize.

Reference

Lindemann K, Kristensen G, Mirza MR, et al. Poor concordance between CA-125 and RECIST at the time of disease progression in patients with platinum-resistant ovarian cancer: analysis of the AURELIA trial. Ann Oncol 2016; Advance online publication 11 July. doi: 10.1093/annonc/mdw238

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