Blood test CA 125: a rule-in test for the diagnosis of women presenting with symptoms of endometriosis

abstract/professional comments
 2016 May 12

BACKGROUND: The development of a non-invasive and accurate diagnostic biomarker for endometriosis is urgently needed.

OBJECTIVE: Evaluate the diagnostic accuracy of serum cancer antigen 125 (CA 125) for endometriosis.

SEARCH STRATEGY: We searched EMBASE, MEDLINE, and Web of Science from inception to January 2016.

SELECTION CRITERIA: Diagnostic accuracy studies of serum CA 125 (index test) for histologically confirmed endometriosis (reference standard) were included.

DATA COLLECTION AND ANALYSIS: Two authors independently selected trials, extracted study characteristics and data. Methodological quality was assessed using Quality Assessment of Comparative Diagnostic Accuracy Studies (QUADAS-2) checklist.

MAIN RESULTS: Twenty-two studies (16 cohort, six case-control), 3626 participants, were identified. Bivariate hierarchical models were used to pool accuracy data of 14 studies (2920 participants) using CA 125 ≥ 30 units/ml. Pooled specificity was 93% (95% CI 89-95%) and sensitivity 52% (95% CI 38-66%). CA 125 was significantly more sensitive for the diagnosis of moderate or severe endometriosis compared with minimal disease (63%, 95% CI 47-77% versus 24%, 95%CI 19-32%, P-value = 0.001).

CONCLUSIONS: CA 125 performs well as a rule-in test facilitating expedited diagnosis and ensuring investigation and treatment can be confidently tailored for the management of endometriosis. Unfortunately, a negative test, CA 125 < 30 units/ml, is unable to rule out endometriosis.

Comments from Clinical Raters
General Internal Medicine-Primary Care(US) As a primary care physician, I don´t see any advantage in the use of CA 125 for ruling-in endometriosis, given that almost 50% of women with endometriosis will have a negative test.
General Practice(GP)/Family Practice(FP) These are good data that would at the very least encourage a more thorough dx approach to rule out endometriosis as well as fallopioovarian pathology.
Gynecology Another tool that adds to the evidence for diagnosis. Unfortunately, it cannot be used to exclude a diagnosis of endometriosis and this will limit its utility.