Introduction CA19.9 is frequently used in the assessment of patients with suspected pancreatic cancer or cholangiocarcinoma. Although specific guidelines are not available, data suggests that it should not be used for screening and only used in conjunction with appropriate imaging. The aim of this study was to investigate the clinical utility and cost effectiveness of using CA19.9 as a marker for pancreatic cancer and cholangiocarcinoma in a district general hospital.
Methods A retrospective analysis was undertaken of all patients with a CA19.9 measurement over a period of 12 months. Data on liver biochemistry and abdominal imaging were collected. The results were compared to identify those patients in whom; (i) a positive CA19.9 result was associated with the presence of biliary or pancreatic malignancy (ii) those patients in whom CA19.9 was inappropriately requested. A cost analysis was undertaken.
Results 492 CA19.9 assays were performed in 12 months. 245 were in patients who had not had abdominal imaging or LFTs measured. 247/492 had both imaging and LFTs and were included in the initial analysis. 102/247 had a positive CA19.9. A total of 45/247 were found to have a pancreatic or bilary malignancy 38/45 had a positive CA19.9. This was negative in 7/45. The overall clinical utility of CA19.9 was poor. From the 492 assays performed during the year a positive CA19.9 was associated with a new malignancy in just 7% (38/492). Overall 63% of patients with a positive CA19.9 did not have pancreatic cancer (PPV 37%) Conversely 5% of those with a negative result did (95% NPV). 22% of patients with pancreatic malignancy had normal LFTs at the time of diagnosis. In total 103/492 (20%) of assays were duplicates. Only 36/103 (35%) were in patients with confirmed malignancy. 67 assays were requested in patients with normal abdominal imaging or in the absence of imaging and LFTs. The total cost for all assays was £7380. £6165 was spent on inappropriate requests or where the diagnosis was not pancreatic malignancy.
Conclusion The clinical utility of CA19.9 is poor with only 7% of samples resulting in a new diagnosis of pancreatic malignancy. The assay is frequently requested inappropriately, often without abdominal imaging being available. LFTS should not be used to guide testing. CA19.9 measurement should only be undertaken in patients where imaging results are available and suggestive of pancreatic malignancy. There are significant cost savings from this approach.
Competing interests None declared.