Risk of Recurrence of Venous Thromboembolism After Major Surgery for Cancer,
Authors: Delluc Aurelien , Crenn Patrice , Le Moigne Emmanuelle , Couturaud Francis , Le Gal Gregoire , Mottier Dominique , Lacut Karine 
Published: October 2019

Abstract
Abstract 3342

Background:
In patients with venous thromboembolism (VTE) provoked by major surgery, the risk of recurrence is low during and after the anticoagulation period. Conversely, cancer patients with VTE have a very high risk of VTE recurrence even under anticoagulant therapy. Some cancer patients develop VTE within three months following surgical treatment of their malignancy. It is unknown whether these patients have a low risk of recurrence of VTE, or if they have the high risk of recurrence associated with cancer.

Methods:
We analyzed data of a single center cohort study conducted at the Brest University Hospital, France. All consecutive cancer patients with pulmonary embolism and/or deep vein thrombosis of the lower limbs diagnosed between January 2000 and July 2009 in our center were followed-up for VTE recurrence. Patients were classified as “surgical” patients if they had major surgery for cancer in the three months before VTE. Probabilities of recurrence of VTE in surgical patients and in non-surgical patients were estimated according to Kaplan-Meier method and were compared by log-rank test. Hazard Ratios (HR) for VTE recurrence and 95% confidence intervals (CI) were obtained using Cox proportional hazard regression models with adjustments on age, sex, past history of VTE, cancer site, and metastases.

Results:
We followed 220 cancer patients with symptomatic VTE (mean age 69.9 ± 11.0 years, male sex n=127 (57.7%)). Of these patients, 42 (19.1%) had major surgery for cancer three months before the index VTE and 178 (80.9%) were non-surgical cancer patients. Surgical patients were more often men (30/42 (71.4%) vs. 97/178 (54.5%), p=0.05) and had less metastases at baseline (7/42 (16.7%) vs. 61/178 (34.3%), p=0.03) than non-surgical patients. Mean age was not different between surgical and non-surgical patients (70.1±10.5 vs. 69.8±11.2, p=0.90). Most surgical patients discontinued anticoagulation after six months of treatment, whereas non-surgical patients were receiving long term anticoagulation. At two years, 29 patients had a recurrence of VTE (2/44 surgical patients and 27/180 non-surgical patients). The cumulative probability of recurrence of VTE was lower in surgical patients than in non-surgical patients (2.8% (95% CI −2.5 to 8.1) vs. 11.3% (95% CI 5.8 to 16.8) at 6 months (p=0.14), 3.0% (95% CI −2.3 to 8.3) vs. 16.2% (95% CI 9.3 to 23.1) at 1 year (p=0.06), and 9.3% (95% CI −4.0 to 22.6) vs. 27.5% (95% CI 18. To 36.9) at 2 years (p=0.04)). At two years, the adjusted hazard ratio for recurrence of VTE was 0.20 (95% CI 0.05 to 0.91) in surgical patients compared with non-surgical cancer patients. There was a trend for a lower cumulative probability of death in surgical patients than in non-surgical patients after two years of follow-up (40.2% (95% CI 23.0 to 57.4) vs. 57.7% (95% CI 49.5 to 65.9), p=0.06).

Conclusion:
In this study, patients with cancer who develop VTE after major cancer surgery had a lower risk of recurrence of VTE than non-surgical cancer patients.

Disclosures:
No relevant conflicts of interest to declare.