# Adjuvant therapeutic efficacy of low-dose aspirin on short-term outcomes of patients with cancer-associated venous thromboembolism

## TL;DR

Adding low-dose aspirin to standard anticoagulant treatment for cancer patients with blood clots reduces recurrence and improves survival, but increases bleeding risk.

## Contribution

This study provides new evidence on the adjuvant therapeutic role of low-dose aspirin in cancer-associated venous thromboembolism.

## Key findings

- Low-dose aspirin reduced VTE recurrence and PE-related mortality in cancer patients.
- Aspirin use was associated with a higher risk of major bleeding.
- Aspirin did not improve all-cause mortality or net clinical benefit.

## Abstract

Although aspirin was reported to have primary thromboprophylactic efficacy on cancer patients, its adjuvant role in the treatment of patients with cancer-associated venous thromboembolism (VTE) has been unclear yet.

Patients with cancer-associated VTE were retrospectively analyzed and divided into aspirin group and non-aspirin group based on whether they underwent low-dose aspirin (100 mg daily) in addition to conventional anticoagulants. Propensity score matching was used to balance baseline characteristics between the aspirin group and non-aspirin group in a 1:2 ratio. The primary, secondary, and tertiary outcomes were VTE recurrence, mortality and major bleeding, and net clinical benefit (NCB), at 6 months after VTE diagnosis, respectively.

The VTE recurrence occurred in 13 (3.1%) in the aspirin group (N = 423) and 55 (6.5%) in the non-aspirin group (N = 846) (hazard ratio [HR] 0.546, 95% confidence interval [CI] [0.298–0.988], P = 0.011). The PE-related mortality occurred in 12 (2.8%) in the aspirin group and 46 (5.4%) in the non-aspirin group (HR 0.535, 95% CI [0.283–0.909], P = 0.037). The all-cause mortality occurred in 108 (25.5%) in the aspirin group and 228 (27.0%) in the non-aspirin group (HR 0.983, 95% CI [0.782–1.237], P = 0.887). The major bleeding occurred in 52 (12.3%) in the aspirin group and 46 (5.4%) in the non-aspirin group (HR 2.448, 95% CI [1.646–3.641], P < 0.001). The NCB occurred in 274 (64.8%) in the aspirin group and 554 (65.5%) in the non-aspirin group (HR 0.976, 95% CI [0.801–1.189], P = 0.812).

For patients with cancer-associated VTE, the adjuvant use of low-dose aspirin based on conventional anticoagulants improves VTE recurrence and PE-related mortality, compared with isolated use of anticoagulants, whereas it does not improve all-cause mortality or net clinical benefit. Adjuvant low-dose aspirin use is associated with an increased risk of bleeding.

The online version contains supplementary material available at 10.1186/s12916-025-04284-8.