Cancer patients who develop a blood clot while on extended apixaban therapy face a very poor short-term prognosis, with half dying within weeks, a new analysis shows.
The post hoc analysis of the API-CAT trial, published in Circulation [link here] and presented at the International Society on Thrombosis and Haemostasis (ISTH) 2026 congress in Paris, examined outcomes in 1766 patients with active cancer who had already completed at least six months of anticoagulation for venous thromboembolism (VTE).
During a further 12 months of apixaban treatment, 42 patients (2.5%) suffered a recurrent VTE. Significantly, 21 of those patients (50%) died during follow-up, at a median of just 24 days after the recurrent clot.
Twelve-month mortality reached 54.8% in patients with recurrent VTE, compared with 18.8% in those without recurrence. Death rates were highest after recurrent symptomatic PE (64.7%) or incidental PE (64.3%), against 36.6% after recurrent DVT.
“The high mortality observed shortly after recurrent VTE… suggests that VTE recurrence during extended therapy is not merely a treatment failure but a critical clinical turning point,” the authors wrote, led by Dr Isabelle Mahé of Hôpital Louis Mourier in Colombes, France.
Most deaths were attributed to cancer progression (n=14), while five were unexplained sudden deaths in which PE could not be excluded, and two followed acute respiratory failure.
Pulmonary embolism dominated both as the index event and the recurrence, with 81% of recurrences occurring in patients whose original clot was a PE, and 76.5% of those recurring again as PE.
Incidental PE also carried a higher recurrence risk than symptomatic PE (4.0% versus 1.4%), reinforcing, the authors said, the case for managing incidental and symptomatic clots the same way during extended treatment.
While the authors cautioned that causality could not be established from the small number of events, they suggested recurrence “may reflect an aggressive cancer disease biology” rather than simple anticoagulant failure.