Risk factors for early versus late venous thromboembolism after cytoreductive surgery and HIPEC

<h2>Abstract</h2><h3>Background</h3> Patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) often have extensive cancer burden, long operative times, and reduced mobility postoperatively – known risk factors for venous thromboembolism (VTE). It is unknown whether risk factors differ for early versus late VTEs post-CRS-HIPEC. <h3>Methods</h3> We retrospectively studied patients undergoing CRS-HIPEC from 2007 to 2021 and analyzed VTEs occurring within 60 days of surgery. VTEs ≤ postoperative day (POD) 7 were "early"; those after POD 7 were "late". Associated risk factors were analyzed using student's t-test, Chi-squared test, and logistic regression. <h3>Results</h3> By POD 60, 35 of 682 CRS-HIPEC patients (5.1 %) had VTEs – eight (22.9 %) early and 27 (77.1 %) late. All early VTEs were pulmonary emboli vs. 63 % of late VTEs (p = 0.041); five (62.5 %) early VTEs were serious (Clavien-Dindo grade ≥3) vs. two (7.4 %) late VTEs (p = 0.005). Early VTEs were associated with primary ovarian cancer (37.5 % vs. 4.2 %, p < 0.001), extensive pelvic dissection (87.5 % vs. 50.1 %, p = 0.035), PCI 31–39 (p = 0.002), OR time (558 vs. 420 min, p = 0.015), EBL (650 vs. 150 mL, p = 0.005), and intraoperative transfusion (62.5 % vs. 13.1 %, p = 0.002). Late VTEs were associated with higher Caprini score (9 vs. 8, p = 0.038), lower serum albumin (4.1 vs. 4.3, p = 0.002), PCI 31–39 (p = 0.012) and serious inpatient postoperative complications (22.2 % vs. 7.3 %, p = 0.008). <h3>Conclusions</h3> Severity and risk factors are markedly different for early vs. late VTEs following CRS-HIPEC. Early VTEs are more serious and associated with primary ovarian cancer and extensive cytoreduction including pelvic dissection highlighting the need for alternative prophylaxis strategies and clinical scrutiny in these populations.