Introduction/Background Gynecologic cancer surgery has 6-fold higher risk for DVT and 14-fold for PE, compared to benign disease. Two meta-analyses (Rasmussen2009, Faragesanu2016) show residual VTE rates 5.3% and 14.3% in patients following standard thromboprophylaxis approach. Despite increased awareness, improved surgical techniques and more extensive use of primary thromboprophylaxis, postoperative DVT remains high.

Methodology MeTHOS is a prospective observational, phase IV study, aiming to evaluate the role of intense thromboprophylaxis (tinzaparin 0.4 ml, 8.000 Anti-Xa IU, OD) for High Thrombotic Burden (HTB) gynecological cancer patients undergoing surgery. Enrolled women had signed informed consent.

Results 221 patients enrolled. Their characteristics in accordance to cancer, patient and treatment high thrombotic burden risk factors are depicted in table 1. Median tinzaparin administration was 29 days (Q1-Q3: 26–34). Eight thrombotic events (TEs) recorded (efficacy:96.4%, 95%CI:93.0–98.2%): 2 in endometrial cancer surgeries, 5 in ovarian, 1 in sarcoma. FIGO-III or IV was linked to higher TE risk, compared to FIGO-I or II (OR: 8.8, p=0.02). Extremely severe (>5 hours) surgeries were prone to TEs, 12% of them followed by TEs, while for major and severe surgeries (2–5 hours) it was 1% and 3% (p=0.04) respectively. 89% of TEs occurred in patients with BMI>29 (OR:76.6, p=0.04). Ovarian cancer surgeries had increased risk for TEs compared to other malignancies (OR:4.2, p=0.04). Three bleeding events reported (1.4%, 95%CI: 0.4–4%). Compared to prophylactic dose, in the two meta-analyses (reported TEs: 5.3% and 14.3%) there were less TEs (3.6%) when intensive dose was applied (p<0.001), without increasing bleeding events (2.8% and 1.8% vs. 1.4% in the current study).

Conclusion Postoperative intense tinzaparin administration 8.000 Anti-Xa IU for 1 month, was both effective and safe. Reducing the occurrence of thrombotic events without increasing bleeding risk. Important risk factors for thromboembolism were BMI≥29, advanced stage disease and ovarian carcinoma. Further research is needed.