# Trajectories of Cancer Antigen 125 (CA125) Within 3 and 6 Months After the Initiation of Chemotherapy Treatment for Advanced Ovarian Cancer and Clinical Outcomes: A Secondary Analysis of Data from a Phase III Clinical Trial

## TL;DR

Tracking CA125 levels during chemotherapy for ovarian cancer can predict patient outcomes better than single measurements.

## Contribution

Longitudinal CA125 trajectories reveal distinct patient groups with varying survival risks during chemotherapy.

## Key findings

- Low baseline and sustained low CA125 levels correlate with the best survival outcomes.
- High baseline CA125 with only modest decreases is linked to the worst survival outcomes.
- CA125 trajectory patterns provide more accurate prognostic information than static measurements.

## Abstract

CA-125 (cancer antigen 125) is a cell surface protein that can be measured in the blood. Levels of CA-125 are often increased in ovarian cancers that express this protein. Previous studies suggested that a single measurement or a summary of a limited number of measurements of the levels of CA125 may be used to forecast the results of treatments for patients with ovarian cancer. In this study, we found that the patterns of change in the levels of CA125 within three or six months after the start of chemotherapy provide more direct information on the results of chemotherapy treatment. Specifically, our study demonstrated a decreased risk of progression and death for patients whose CA125 levels were low at the start of the treatment and remained low during the treatment and an increased risk when patients’ CA125 levels remained elevated. This information may be useful for patient monitoring.

Background: A single measurement or a summary of a limited number of measurements of CA125 was considered in the prediction of clinical outcomes for patients with ovarian cancer. We aimed to identify the classes of patients with advanced ovarian cancer based on their CA125 trajectory and to investigate the heterogeneity of clinical outcomes among the patients in the different classes. Methods: CA125 trajectory classes were identified by latent-class mixed models based on values collected within 3 and 6 months post-treatment for 819 women with advanced ovarian cancer enrolled in a randomized trial. Results: Based on their CA125 values during the first 6 months of treatment, the patients with low CA125 levels at baseline that remained low during treatment had the best clinical outcome (a median survival of 83 months and a progression-free survival of 34 months). In contrast, the patients with high CA125 values at baseline with a modest decrease during treatment had the highest risk of death and progression (hazard ratio [95% confidence interval]: 4.83 [3.56, 6.54] for overall survival and 5.15 [3.87, 6.87] for progression-free survival). Conclusions: Longitudinal trajectories of CA125 may provide more direct information for the prognoses of patients with advanced ovarian cancer undergoing chemotherapy treatment.