What is the role of serum CA 125 testing in detection of tumor recurrence?

Updated: Jan 10, 2020
  • Author: Gentry George T King, MD; Chief Editor: Eric B Staros, MD  more...
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Rising levels of CA 125 in the absence of clinical or radiographic findings indicate what is termed as a biochemical relapse, which precedes a clinically detected relapse by 2-6 months. [4] Although increasing CA 125 levels correlate with tumor recurrence after primary treatment, management of biochemical relapses remain controversial. A recent study concluded that positron emission tomography (PET/CT) scanning is useful in diagnosing relapses in patients with a CA 125 value of at least 17.6 U/mL. [9]

A recent European collaborative study suggests that early treatment of biochemical relapse does not provide survival benefit and is associated with a decreased quality of life. [10] However, limitations of the study include the lack of a standardized second or third line of chemotherapy, since agents evolved over the 10-year accrual period. Furthermore, there were no surgical considerations in terms of optimal versus suboptimal primary or secondary cytoreductive surgeries or whether the tumors were platinum sensitive or resistant. As such, the National Comprehensive Cancer Network (NCCN) recommends that physicians discuss the pros and cons of monitoring CA 125 levels with their patients. If rising CA 125 levels are detected, enrollment in a clinical trial or observation until onset of symptoms or clinically detected disease arises is recommended. [4]

Increased levels of CA 125 also correlate with the presence of tumor in a second-look operation after primary treatment with debulking surgery and chemotherapy. CA 125 levels above 35 units/mL predict the presence on second-look operation with 95% accuracy. [11, 12] However, the false-negative rate is high, with a range of 50%-60% in some studies; as such, the necessity of a second-look cannot be judged based solely on CA 125 levels. [13] Moreover, second-look laparotomy is currently considered controversial and is offered only in patients enrolled in clinical trials or when surgical findings alter subsequent management.

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