Using a CA19-9 Tumor Marker Gene Test to Assess Outcome After Pancreatic Cancer Surgery

BACKGROUND

Cancer antigen 19-9 (CA19-9) is widely used as a marker of pancreatic cancer tumor burden and response to therapy. Synthesis of CA19-9 and its circulating levels are determined by variants encoding the fucosyltransferases, FUT2 and FUT3. Individuals can be grouped into one of four functional FUT groups (FUT3-null, FUT-low, FUT-intermediate, FUT-high), each with its own CA19-9 reference range based on its predicted capacity to produce CA19-9. The authors hypothesized that a FUT variant-based CA19-9 tumor marker gene test could improve the prognostic performance of CA19-9.

METHODS

Preoperative and pre-treatment CA19-9 levels were measured, and FUT variants were determined in 449 patients who underwent surgery for pancreatic ductal adenocarcinoma (PDAC) at Johns Hopkins Hospital between 2010 and 2020, including 270 patients who underwent neoadjuvant therapy. Factors associated with recurrence-free and overall survival were determined in Cox proportional hazards models.

RESULTS

Higher preoperative CA19-9 levels were associated with recurrence and mortality for patients in the higher-FUT groups (FUT-intermediate, FUT-high for mortality, with adjustment for other prognostic factors; hazard ratio [HR], 1.34 and 1.58, respectively; P < 0.001), but not for those in the lower-FUT groups (FUT3-null, FUT-low). As a tumor marker, CA19-9 levels of 100 U/ml or lower after neoadjuvant therapy and normalization of CA19-9 based on FUT group were more sensitive but less specific predictors of evidence for a major pathologic response to therapy (little/no residual tumor) and of early recurrence (within 6 months).

CONCLUSION

Among patients undergoing pancreatic cancer resection, a CA19-9 tumor marker gene test modestly improved the prognostic performance of CA19-9.

The role of biomarkers in the early detection of pancreatic cancer

Pancreatic surveillance can detect early-stage pancreatic cancer and achieve long-term survival, but currently involves annual endoscopic ultrasound and MRI/MRCP, and is recommended only for individuals who meet familial/genetic risk criteria. To improve upon current approaches to pancreatic cancer early detection and to expand access, more accurate, inexpensive, and safe biomarkers are needed, but finding them has remained elusive. Newer approaches to early detection, such as using gene tests to personalize biomarker interpretation, and the increasing application of artificial intelligence approaches to integrate complex biomarker data, offer promise that clinically useful biomarkers for early pancreatic cancer detection are on the horizon.