The platelet-lymphocyte ratio improves the predictive value of serum CA19-9 levels in determining patient selection for staging laparoscopy in suspected periampullary cancer

Background. The objective of this study was to identify whether the preoperative platelet-lymphocyte (P/L) ratio might improve the predictive value of CA19-9 levels in stratifying a patient group with suspected periampullary malignancy who do not require staging laparoscopy. Methods. Patients with suspected periampullary cancer were identified from a prospectively maintained 10-year database. Only patients with resectable disease who underwent staging laparoscopy and subsequent laparotomy were included. Low-risk groups were stratified using a CA19-9 cutoff value of <= 150 kU/l (or <= 300kU/l in patients with a concurrent bilirubin concentration > 35 mu mol/l) and a P/L ratio value of <= 150. Results. From 263 patients, preoperative CA19-9 levels and P/L ratios were available in 216 and 225 patients, respectively. The positive and negative predictive values for resectability, sensitivity, and specificity for CA19-9 levels <= 150kU/l were 83%, 36%, 51%, and 73%, respectively. For P/L ratios <= 150, these levels were 81%, 38%, 51%, and 72%, respectively. When combining the requirement for both CA19-9 levels and P/L ratios to be <= 150 (n=38 out of 183), both positive predictive value (95%) and specificity (96%) were improved (Fisher exact test, P=.065 and P <.001, respectively); 21% of laparoscopies were avoidable when using these criteria. Increasing T stage (P=.005), vascular invasion (P <.001), perineural invasion (P=.008), and resection margin involvement (P <.001) were all associated with greater preoperative P/L ratios in resected periampullary adenocarcinoma (n=204). Conclusions. The preaperative P/L ratio reflects an index of tumor invasiveness and merits prospective evaluation as an adjunct to CA19-9 in determining the requirement for laparoscopic staging in patients with potentially resectable periampullary malignancy.