Appropriate requesting of serum tumour markers

The patient

A 54 year old woman presented to her general practitioner with swelling of her abdomen, general malaise, and weight loss of about 5 kg during the preceding three months. On examination, she had a slightly distended abdomen and evidence of ascites. No masses could be felt.

The general practitioner ordered routine biochemistry tests as well as requesting CA125, CEA (carcinoembryonic antigen), and CA19.9 tumour markers, as he believed these would help him judge the likelihood of ovarian, colonic, and pancreatic cancers. The results of these and routine biochemistry are shown in the table⇓.

An urgent gynaecological oncology referral was arranged to exclude ovarian cancer. Both abdominal ultrasound and computerised tomography confirmed ascites, but showed no ovarian mass or intra-abdominal malignancy. However, the liver was atrophic and showed a diffuse surface irregularity. Subsequent testing found hepatitis C infection with hepatitis C virus RNA detectable in the serum, and a liver biopsy confirmed cirrhosis. The history included no obvious risk factors for the hepatitis C infection.

What should the next investigation have been?

This case highlights the limitations of using most serum tumour markers to …