Declining CA-125 in an ovarian cancer patient with progression of measurable disease: a rational hypothesis for discordant results

Concordance between CA-125 and RECIST progression in patients with germline BRCA-mutated platinum-sensitive relapsed ovarian cancer treated in the SOLO2 trial with olaparib as maintenance therapy after response to chemotherapy

BACKGROUND

Limited evidence exists to support CA-125 as a valid surrogate biomarker for progression in patients with ovarian cancer on maintenance PARP inhibitor (PARPi) therapy. We aimed to assess the concordance between CA-125 and Response Evaluation Criteria in Solid Tumours (RECIST) criteria for progression in patients with BRCA mutations on maintenance PARPi or placebo.

METHODS

We extracted data on progression as defined by Gynecologic Cancer InterGroup CA-125, investigator- and independent central-assessed RECIST from the SOLO2/ENGOT-ov21(NCT01874353) trial. We excluded those with progression other than by RECIST, progression on date of randomisation, and no repeat CA-125 beyond baseline. We evaluated the concordance between CA-125 progression and RECIST progression, and assessed the negative (NPV) and positive predictive value (PPV).

RESULTS

Of 295 randomised patients, 275 (184 olaparib, 91 placebo) were included. 171 patients had investigator-assessed RECIST progression. Of 80 patients with CA-125 progression, 77 had concordant RECIST progression (PPV 96%, 95% confidence interval 90-99%). Of 195 patients without CA-125 progression, 94 had RECIST progression (NPV 52%, 45-59%). Within treatment arms, PPV was similar (olaparib: 95% [84-99%], placebo: 97% [87-100%]) but NPV was lower in patients on placebo (olaparib: 60% [52-68%], placebo: 30% [20-44%]). Of 94 patients with RECIST but without CA-125 progression, 64 (68%) had CA-125 that remained within normal range. We observed similar findings using independent-assessed RECIST.

CONCLUSIONS

Almost half the patients without CA-125 progression had RECIST progression, and most of these had CA-125 within the normal range. Regular computed tomography imaging should be considered as part of surveillance in patients treated with or without maintenance olaparib rather than relying on CA-125 alone.

Serum tumor markers in the management of ovarian, endometrial and cervical cancer

CA 125 is the most reliable serum marker for ovarian carcinoma. Whereas its role in the screening of the malignancy is controversial, serum CA 125 assay is very useful for both the differential diagnosis of ovarian masses, particularly in postmenopause, and the monitoring of the response to chemotherapy and follow-up of patients with histologically proven ovarian carcinoma. Tumor-associated antigens other than CA 125, such as CA 19.9, CA 15.3 and TAG.72, firstly identified in gastro-intestinal or breast malignancies, have been detected also in tissue and serum samples from patients with ovarian carcinoma. In particular CA19.9 offers the advantage of high sensitivity for mucinous histotype, which often fails to express CA 125. Serum CA 125 correlates with the clinical course of disease better than the other antigens, and in patients with positive CA 125 assay at diagnosis the concomitant evaluation of CA 19.9 or CA 72.4 or CA 15.3 does not offer any additional benefit for monitoring ovarian carcinoma. Conversely, the serial measurements of these other antigens may represent an interesting biochemical tool for the management of patients with negative CA 125 assay. Serum alphaFP and betaHCG are very useful in the preoperative evaluation and management of nondysgerminomatous ovarian germ cell tumors, whereas elevated serum inhibin levels can be detected in patients with granulosa cell tumors of the ovary. As for endometrial carcinoma, preoperative serum CA 125 levels correlate with stage, depth of myometrial invasion, histologic grade, cervical invasion, peritoneal cytology, lymph node status and clinical outcome. Moreover, serial CA 125 assay is a good indicator of disease activity and a useful biochemical tool for post-treatment surveillance of patients with endometrial carcinoma. SCC is the most reliable serum marker for squamous cell cervical carcinoma, and in patients with this malignancy pretreatment SCC levels are related to tumor stage, tumor size, depth of cervical invasion, lymph-vascular space involvement, lymph node status and clinical outcome. Serial SCC measurements parallel the response to radiotherapy and chemotherapy as well as the clinical course of disease after the completion of treatment. Serum CYFRA 21.1 seems to be less sensitive than serum SCC for squamous cell cervical carcinoma. Elevated CA 125 levels can be often detected in patients with cervical adenocarcinoma. The future for tumor marker research is represented by the emerging technologies of transcriptional profiling and proteomics.

Potential clinical utility of CA-125 in responsive but persistent large-volume ovarian cancer following platinum-based chemotherapy

BACKGROUND

Despite the demonstrated clinical utility of the serum CA-125 antigen level in ovarian cancer, controversy exists regarding interpretation of "discordant" results between changes in this tumor marker and measurable disease masses.

CASE

A patient with ovarian cancer cared for in the Gynecologic Cancer Program of the Cleveland Clinic Foundation receiving second-line single-agent carboplatin for recurrent disease demonstrated a major response in serum CA-125, but minimal shrinkage of a large painful abdominal mass. A laparotomy was performed both to define the nature of this mass and to attempt to relieve symptoms. The mass was found to be a large "inflamed pseudotumor with central necrosis." No viable tumors cells were found.

CONCLUSION

This case represents an excellent example of the remarkably complex biology of malignant disease and suggests how evaluation of changes in CA-125 in women with ovarian cancer may be utilized in individual patients to develop optimal management plans.