Abstract
<title>Abstract</title> <p> <bold>Background.</bold> Venous thromboembolism (VTE) is a leading cause of preventable death in patients with cancer. Existing risk scores were derived in Western, mixed-cancer populations and rely on variables (body-mass index, P-selectin, performance status) that are frequently unavailable in low and middle-income countries (LMICs). No simple, gastrointestinal (GI) - specific score exists for these settings. We aimed to develop and internally validate a three-component VTE risk score for GI cancers using only routinely available data. <bold>Methods.</bold> In a cross-sectional study of 207 patients with histologically confirmed GI cancer, we developed GIVE-VTE-3, which assigns one point each for: a high-risk cancer site (pancreas, liver, biliary tract, or gallbladder), D-Dimer ≥ 3,000 ng/mL, and an absolute monocyte count ≥ 0.8 G/L (range 0–3). VTE was confirmed by imaging. Discrimination was quantified by the area under the receiver-operating-characteristic curve (AUC) with bootstrap optimism correction (1,000 iterations) and five-fold cross-validation; calibration by the Hosmer-Lemeshow test; and clinical utility by decision-curve analysis. GIVE-VTE-3 was compared with the Khorana score, an ONKOTEV-like model, and D-Dimer alone. Generalisability was explored in an independent multi-cancer cohort (n = 516). <bold>Results.</bold> The VTE rate was 22.7% (47/207). GIVE-VTE-3 stratified VTE risk across an approximately tenfold gradient: low (score 0) 6.9%, medium (1–2) 25.9%, and high (3) 70.0%. The optimism-corrected AUC was 0.694 (95% CI 0.609–0.777) with good calibration (Hosmer-Lemeshow p = 0.403). At a score of 3, the positive predictive value was 70.0% and the positive likelihood ratio 7.94; at a score of 0, the negative predictive value was 93.1%. GIVE-VTE-3 outperformed the Khorana score (AUC 0.469; ΔAUC + 0.226, p < 0.001), an ONKOTEV-like model (0.608), and D-Dimer alone (0.574). In the exploratory multi-cancer cohort, the integer-score AUC was 0.773 (95% CI 0.718–0.829), with a continuous - model AUC of 0.802, suggesting applicability beyond GI cancers. <bold>Conclusions.</bold> GIVE-VTE-3 is a simple, low-cost score that stratifies VTE risk in GI cancer patients and is immediately deployable in LMIC settings. The inclusion of monocyte count - an inexpensive, routinely measured but seldom-used marker - distinguishes it from existing scores. </p>