Liver function tests not useful for detecting uveal cancer metastasis
MedWire News: Liver function testing (LFT) does not help the early detection of liver metastasis in uveal melanoma patients, show study results.
However, the test does have a high negative predictive value (NPV), which means physicians can reassure their patients when LFT results are negative, say the researchers.
"Uveal melanoma is remarkable for hematogenous dissemination and its high tendency to metastasize to the liver," say Frédéric Mouriaux (CHU de Caen Cote de Nacre, France) and colleagues in Ophthalmology.
And while there are currently no therapies known to prolong survival in uveal melanoma patients who do develop metastasis, early detection is desirable for "multicenter adjuvant therapy or for multicenter randomized clinical trials, and it may help the patient and family in planning medical and personal care," writes the research team.
While the expected level of metastasis detection using LFT is around 90%, Mouriaux and co-investigators report that just 45% of 88 uveal melanoma patients in their study with metastasis had at least one abnormal LFT result after a mean 53-month follow up.
However, this could be a result of metastasis occurring first in sites other than the liver, they note.
Sensitivity analysis of the metastatic patients and 174 control uveal melanoma patients without metastasis, revealed an overall sensitivity of LFT of between 12.5% and 58.0%, while specificity was between 79.7% and 99.2%.
Positive predictive values (PPV) were just 39.0%, suggesting LFTs would not be helpful for clinicians to use to diagnose metastases in patients with positive LFT results, remark Mouriaux et al.
By contrast, they found that NPVs were high across LFT, including 97.5% for alanine aminotransferase, 97.8% for aspartate aminotransferase, and 98.1% for lactate dehydrogenase.
The problem with abnormal LFT results, results that are not trusted to indicate the presence or absence of metastasis, and even normal results that require confirmation, is that they lead to an increase in requests for imaging, which has financial considerations, they write.
Specifically, the team calculated that LFT testing would cost a mean CAN$ 35.5 per year, but that it could vary from €31.9 per year in France to US$ 273 per year in the USA, according to those countries' imaging protocols.
By Sarah Guy