Role of Extended Thromboprophylaxis after Abdominal and Pelvic Surgery in Cancer Patients: A Systematic Review and Meta-Analysis
Bibliographic record
Abstract
Abstract Introduction Abdominal or pelvic surgery for cancer increases the risk of postoperative venous thromboembolism (VTE) by 2- to 3-fold. The use of low-molecular weight heparin (LMWH) to prevent post-operative thrombotic events is recommended in high VTE-risk patients; however, the role of extended thromboprophylaxis in this setting is controversial. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) and prospective observational studies to determine the effect of extended LMWH thromboprophylaxis on all VTE, deep vein thrombosis (DVT), pulmonary embolism (PE), major bleeding, and all-cause mortality after abdominal or pelvic surgery for cancer. Methods We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials, conference abstracts, and trial registries with no language restriction. Studies were included if they compared extended duration (i.e., administration of prophylactic doses of LMWH for more than 2 weeks, up to 6 weeks) versus conventional duration of thromboprophylaxis (i.e., administration of LMWH for two weeks or less) after cancer surgery. Two reviewers independently performed study selection, data extraction, and quality assessment. Studies were evaluated according to a priori inclusion criteria and critically appraised using the Newcastle-Ottawa Quality Assessment Scale (NOQA). Pooled relative risk was estimated using a random effects model. Results Three RCTs and 4 observational studies were included, comprising 4807 adult patients who underwent open or laparoscopic abdominal or pelvic surgery for gastrointestinal, gynecological or urological cancers. The 3 RCTs employed screening for asymptomatic DVT using bilateral lower limb compression ultrasound or venography after 4 weeks of surgery. Most of studies were of good quality (NOQA higher or equal to 6). The extended thromboprophylaxis regimen was associated with a significantly reduced incidence of all VTE (2.6% [59/2292] vs 5.6% [124/2209]; RR=0.44 [95% CI 0.28-0.70]) and proximal DVT (1.4% [14/966] vs 2.8% [24/862]; RR=0.33 [95% CI 0.15-0.73]). No data were available for symptomatic DVT. There was no statistically significant difference in the incidence of symptomatic PE between the two groups (0.8% [8/966] vs 1.3% [11/862]; RR= 0.56 [95% CI 0.23-1.40]). We found no significant difference in major bleeding at 1.8% (14/787) in the extended thromboprophylaxis group vs 1.0% (7/713) in the short thromboprophylaxis group (RR=1.19 [95% CI 0.47-2.97]). There was no significant difference in all-cause mortality at 3 months (4.2% [30/720] vs 3.6% [23/643], respectively; RR= 0.79 [95% CI 0.47-1.33]). There was minor heterogeneity between the studies in all extracted outcomes. Conclusion Extended thromboprophylaxis with LMWH after abdominal or pelvic surgery for cancer significantly decreased the incidence of all VTE and proximal DVT, but had no impact on symptomatic PE, major bleeding or 3-month mortality. Table 1. Table 1. Disclosures Lee: Pfizer: Consultancy, Honoraria; LEO Pharma: Consultancy, Honoraria; BMS: Research Funding; Bayer: Consultancy. Wu:Leo Pharma: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.016 | 0.037 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.019 | 0.034 |
| Bibliometrics | 0.006 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".