CA 125 - Tumour Marker
Investigation : CA 125 - Tumour Marker
Specimen type : Serum
Spec container : Serum Gel 
Volume required : 5 ml
Reference range : <35 KU/l
Turnaround : <48 hours

Prior to 29/08/2014, the reference range was <25 KU/L.

Cancer antigen (CA) 125
CA 125 is a high molecular weight glycoprotein.

Malignancies with elevated CA 125:
CA 125 is elevated in 50% of women with stage I epithelial ovarian cancer, in 90% of stage II and in >90% stages III and IV. Concentrations correlate with tumour burden and stage.
CA 125 may be elevated in any adenocarcinoma with advanced disease.

NICE Ovarian cancer recognition guidelines (2011) here..

NICE Quality Standard for Ovarian Cancer here..

Ovarian Cancer Map of Medicine Pathway here..

Benign conditions which may have elevated CA 125:
Elevated values may be found in 1 - 2 % normal healthy individuals. Blood for CA 125 should not be taken during menstruation which may increase serum concentrations 2 - 3 fold. CA 125 may be mildly elevated in endometriosis and during the first two trimesters of pregnancy. CA 125 may be high in acute pancreatitis, cirrhosis, peritonitis and inflammatory pelvic disease and may be markedly raised in any patient with benign ascites.

Main clinical applications:

Discrimination of suspicious pelvic masses
CA 125 may be used as an adjunct in distinguishing benign from malignant disease in women, particularly postmenopausal women presenting with ovarian masses. Benign conditions resulting in elevated CA 125 levels may be a confounding factor in premenopausal women.
Detection of recurrence of ovarian carcinoma post-operatively
Elevated or rising CA 125 concentrations predict relapse. However, negative values do not exclude disease presence.
Monitoring treaatment
Serial measurement of CA 125 may play a role in monitoring response to chemotherapy. . An inadequate fall in concentration during chemotherapy suggests that treatment is being unsuccessful.
Determining prognosis
Both pre-operative and post-operative CA 125 concentrations may be of prognostic significance. The rate of decline during initial therapy is a strong and independent prognostic indicator in ovarian carcinoma.

Measure CA125 if a woman (especially if 50 or over) reports having any of the following symptoms on a persistent or frequent basis - particularly more than 12 times per month:
- persistent abdominal distension (women often refer to this as ‘bloating’)
- feeling full (early satiety) and/or loss of appetite
- pelvic or abdominal pain
- increased urinary urgency and/or frequency.

CA125 should also be measured in any woman of 50 or over who has experienced symptoms within the last 12 months that suggest irritable bowel syndrome (IBS), because IBS rarely presents for the first time in women of this age.

NICE guidelines link

Additional information on CA125 and its clinical use can be found here: CA125.

AUH service users: new CA125 units kU/L are equivalent to previous (U/mL).

ICE requesting info:ICE panel nameICE page nameColumnComment\Advice
Chem / Haem
Endo & Oncology


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