Treatment response in advanced ovarian cancer (AOC): Evaluation of tumor metabolism, CA-125, and RECIST criteria

Objectives Because most women treated for AOC suffer recurrence, there is a need for better and more effective methods of assessing early treatment response. We evaluated baseline and treatment induced changes in tumor metabolism and CA-125 with RECIST-based response.

Methods Nine patients with proven AOC underwent sequential dynamic FDG scans (0-45 min) before neoadjuvant chemotherapy (3 cycles); 7 were rescanned after the 3rd cycle. Using a 2-tissue compartmental model, kinetic analysis was performed on the lesion with the highest SUVmax. FDG phosphorylation rate constant (k3), FDG influx (Ki), and standardized uptake value (SUV) were generated. Early treatment response was also evaluated using serum CA-125 levels and standard RECIST criteria.

Results By RECIST criteria, 6 patients had partial response (PR) and 3 had non-response (NR). In logistic regression analysis, neither pre-tx CA-125, SUV, Ki nor k3 were significantly associated with PR or NR, although we observed a trend toward young age (OR=0.82, 95% CI 0.62-1.08 per year) associated with NR. Similarly, post-tx values and change in CA-125, SUV, Ki and k3 were not significantly associated with PR or NR, although we observed trends of maxSUV (OR=1.8, p=0.29), k3 (OR=1.23, p=0.27 per percent), small percent drop in pre to post-tx SUV (OR=0.94, p=0.26) and high post-tx CA-125 (OR=5.3, p=0.23 per log10) associated with NR.

Conclusions In this small study of AOC, neither pre-tx nor post-tx CA-125 values, nor change in CA-125, SUV, peak Ki or peak k3 were significantly associated with NR to neoadjuvant chemotherapy as determined by RECIST. However, trends associating NR with young age, high post-tx CA-125, maxSUV, peak k3 and small pre- to post-tx reduction in maxSUV were observed. Further research in a larger cohort of patients is warranted.

Research Support NIH grant 1R21CA13583