The assessment of pancreatic exocrine function in patients with inoperable pancreatic cancer: in need of a new gold-standard.

Background
Pancreatic exocrine insufficiency is commonplace in patients with pancreatic cancer, adversely impacting on quality of life and survival. Whilst the management of exocrine insufficiency is well established, diagnosis remains challenging in clinical practice. A plethora of diagnostic tests exist. Nevertheless, a lack of consensus remains about the optimal diagnostic method, specifically in patients with pancreatic cancer. Research, to date, has primarily been undertaken in patients with chronic pancreatitis and cystic fibrosis.
This manuscript will review the current literature and will examine the evidence around the diagnostic tests available for pancreatic exocrine insufficiency and whether any exists specifically for pancreatic cancer cohorts.

Findings
Evidence to recommend an individual test for the diagnosis of pancreatic exocrine insufficiency in clinical practice is lacking. Direct testing (by direct sampling of pancreatic secretions) has the highest specificity and sensitivity but is no longer routinely deployed or feasible in practice. Indirect testing, such as faecal elastase, is less accurate with high false-positive rates, but is routinely available in clinical practice. The 13C-mixed triglyceride breath test and the gold-standard 72-hour faecal fat test have high specificity for indirect tests, but are not routinely available and cumbersome to undertake. A combination approach including nutritional markers and faecal elastase has more recently been proposed.

Conclusion
Further research is required to identify the most optimal and accurate diagnostic tool to diagnose pancreatic exocrine insufficiency in patients with pancreatic cancer in clinical practice.