Ca-125 in Ovarian Cancer: To Test or Not to Test?

I saw a patient yesterday with advanced ovarian cancer. She is young but unfortunately the disease had spread to her liver. Can tumor markers (Ca-125) help to detect her disease much earlier?

Ovarian cancer

One of the commonest cancer in women:

  • Epithelial ovarian cancer formed the majority of the ovarian cancer cases (90%).
  • The estimated lifetime risk for a woman developing ovarian cancer is about 1 in 54.

Unfortunately, ovarian cancer normally present at more advance stage because patient normally have no/ minimal signs and symptoms

  • The abdomen has large space for ovarian cancer to grow without causing any symptoms
  • When symptoms start to appear, the ovarian cancer already locally advanced or spread to other parts of the body

5-year average overall survival (OS) decreased markedly from 90-95% in stage 1 to just 20-25% in stage 3 and even much lower for stage 4 ovarian cancer.

Early detection

Early detection at stage 1 not only increases survival and cure rate but also allow fertility sparing surgery in younger patients.

So, how do you detect ovarian cancer early that comes with no symptoms? If one is to wait for symptoms to appear, it’s already in advance stage.

Serum tumor marker Ca-125 is used in ovarian cancer to help in initial detection and diagnosis of epithelial ovarian cancer.

Screen Shot 2018-06-11 at 10.05.53 PM.png
Tumor marker CA-125

The accepted normal level is <35U/ml. Serum tumor marker Ca-125 is raised in 50% and 85% of early and advanced ovarian cancer respectively.

However, a normal results might still not rule out other non-epithelial ovarian cancer such as germ cell tumor, ovarian stromal tumor, etc., especially if there are accompanying symptoms.

Finally

So, should everyone be screened using serum tumor marker Ca-125 to detect early ovarian cancer?

It’s not recommended to screen for early ovarian cancer in one large study involving more than 20000 post-menopausal women with average risk of ovarian cancer, comparing those screened annually using Ca-125 or normal gynaecological care (Rauh-Hain JA, 2011)

  • There is no different in the number of death due to ovarian cancer in either group
  • Furthermore, only 6 ovarian cancer cases were detected after more than 8000 women were screened using Ca-125; and only 3 out of 6 of the ovarian cancer detected were in early stage (6600 patients need to be tested to detect 1 early ovarian cancer)

CA-125 mainly used to monitor response to surgery, chemotherapy, relapse and disease progression

Anyway, with cost of tumor marker testing getting cheaper and being included in most health screening packages, I personally welcome these testing because detecting an early ovarian cancer make a huge difference to patient, which no statistic results or cost-analysis can justify, if one can afford.

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