What is the significance of an elevated Cancer Antigen (CA) level?

From the Guidelines

Elevation of CA levels should not prompt immediate treatment, but rather should be interpreted in the context of clinical symptoms and further diagnostic testing, as early intervention based on elevated CA 125 levels has not shown a survival advantage and may decrease quality of life. The management of elevated CA levels, particularly CA-125, is complex and depends on various factors, including the presence of symptoms, disease history, and patient preferences 1. Some key points to consider include:

• Elevated CA 125 levels can indicate ovarian cancer recurrence, but early treatment based on these levels alone does not improve overall survival (OS) 1.
• A phase III randomized study (OV05-EORTC 55955) found that delaying treatment until clinical evidence of relapse did not detract from OS, and instead, resulted in a better quality of life for patients 1.
• The use of PET-CT scans can help identify sites of disease not visible on CT scans, which can inform decisions about secondary debulking surgery 1.
• Patient preferences and local follow-up practices play a significant role in determining the management approach for elevated CA levels 1.
• It is essential to interpret CA levels in conjunction with clinical symptoms, imaging studies, and possibly biopsies to confirm or rule out cancer, and to develop an appropriate treatment plan 1.

From the Research

Elevation of CA Level

• The elevation of CA 125 levels is often associated with ovarian cancer, particularly type II tumors which are usually diagnosed in advanced stages and have significantly higher CA 125 levels than type I tumors 2.
• A study found that CA 125 had the highest pooled specificity, 0.93 (95% CI: 0.89-0.95), in diagnosing recurrent ovarian carcinoma, while PET-CT had the highest pooled sensitivity, 0.91 (95% CI: 0.88-0.94) 3.
• The use of CA 125 tests for routine surveillance in ovarian cancer has been shown to increase the use of chemotherapy and decrease patients' quality of life without improving survival, compared with clinical observation 4.
• CA 125 levels have been found to correlate significantly with laparotomic findings in patients with ovarian cancer, with median CA 125 values in patients with residual tumors and in tumor-free patients following intraperitoneal chemotherapy being 14.6 (1-775) and 7.2 (1-37) U/ml, respectively 5.
• While CA 125 levels can be useful in monitoring ovarian cancer, they are not sufficient to replace a laparotomy due to a high false-negative rate, and a normal CA 125 value is not sufficient to rule out the presence of disease 5.

Diagnostic Accuracy

• The diagnostic accuracy of CA 125 levels and imaging modalities such as CT scans and PET-CT has been evaluated in several studies, with results showing that while these tests can be useful in diagnosing and monitoring ovarian cancer, they are not perfect and can have limitations 3, 5.
• A study found that the area under the curve (AUC) of CA 125, PET alone, PET-CT, CT, and MRI were 0.9219,0.9297,0.9555,0.8845, and 0.7955, respectively, in diagnosing recurrent ovarian carcinoma 3.
• The use of CA 125 tests and CT scans for surveillance in ovarian cancer has been shown to be common in clinical practice, despite the lack of evidence supporting their benefit in improving survival 4.

Clinical Implications

• The elevation of CA 125 levels can have significant implications for patients with ovarian cancer, including the potential for increased use of chemotherapy and decreased quality of life 4.
• The use of CA 125 tests and imaging modalities such as CT scans and PET-CT can be useful in diagnosing and monitoring ovarian cancer, but should be interpreted in the context of other clinical and radiological findings 3, 5.
• Further research is needed to evaluate the optimal use of CA 125 tests and imaging modalities in the diagnosis and management of ovarian cancer 2, 4.