Prolonged prophylaxis against venous thromboembolism with enoxaparin in patients undergoing cancer surgery: long-term survival analysis

Abstract

Objective: ENOXACAN II was a randomized, double-blind trial that showed prolonged (four-week) thromboprophylaxis with enoxaparin to be more effective than and as safe as standard (one-week) thromboprophylaxis in patients undergoing surgery with a curative intent for abdominopelvic cancer. This follow-up study compared long-term, all-cause mortality in both groups.

Methods: Survival rates were calculated on the randomized, treated population (n = 501). The primary efficacy endpoint was survival at one year. An exploratory analysis including survival data up to 44 months was performed. Because some patients were deemed to have undergone palliative as opposed to curative surgery, and there was a significant difference between the treatment groups in the percentage of patients undergoing palliative surgery, the survival analyses were adjusted for the type of surgery performed.

Results: When adjusted for type of surgery, there was a trend towards reduced mortality among patients undergoing palliative surgery in the prolonged prophylaxis group (hazard ratio [HR] = 0.598, P = 0.3565) that became more pronounced beyond the pre-specified one year follow-up period (HR = 0.469, P = 0.078). This trend may reflect a beneficial effect of prolonged prophylaxis on survival in the palliative surgery group (one-year survival 65.4 versus 50% for standard prophylaxis). In patients undergoing curative surgery, one-year survival rates were equal in the standard and prolonged prophylaxis groups (93.8 and 93.2%, respectively).

Conclusion: Prolonged thromboprophylaxis with enoxaparin may affect long-term survival in palliative surgery for cancer, but further investigation is warranted.