Primary Thromboprophylaxis in People With Cancer—Where Next?
Mené sur 328 patients atteints d'un cancer gastrointestinal ou d'un cancer du poumon (âge médian : 65 ans), cet essai randomisé de phase III évalue l'efficacité, du point de vue de la présence d'une thromboembolie au jour 180, d'un traitement prophylactique de la thromboembolie par énoxaparine, dispensé en fonction d'un score basé sur les niveaux de fibrinogène et de D-dimères
Four facts should be abundantly clear to oncologists after the flurry of research investigating cancer-associated venous thromboembolism (VTE) in the past decade or so. One, VTE remains a highly prevalent illness complicating cancer and its treatments, even with newer drugs like immune checkpoint inhibitors. Second, the occurrence of VTE (and its corollary, arterial thromboembolism [ATE]) is unequivocally bad for people with cancer. Associated outcomes include high rates of emergency department visits and hospitalizations, delay or interruption of cancer treatment, and—most worryingly—increased mortality. Third, the known high prevalence of VTE should not blind oncologists to the dramatic variation in rates between subgroups of the cancer population (eg, between patients with breast and pancreatic cancer). Validated risk assessment tools can, however, help identify patients at low and high risk for VTE. Fourth, multiple randomized clinical trials (RCTs) have shown that low-molecular-weight heparins (LMWHs) and direct oral anticoagulants such as rivaroxaban and apixaban are highly effective and relatively safe in the primary prevention of VTE in people with cancer. In a meta-analysis of 6 RCTs involving more than 4500 ambulatory patients with cancer, these agents meaningfully reduced VTE risk in intermediate- to high-risk patients (risk ratio, 0.51; 95% CI, 0.34-0.67). Risk was defined using the Khorana score, the first validated risk assessment tool in this setting and the only one used thus far as an entry criterion in RCTs. In terms of clinical benefit, the number needed to treat (NNT) to prevent 1 VTE varied by cutoff of risk: ranging from 25 (intermediate to high risk, Khorana score ≥2) to 17 (high risk, Khorana score ≥3). The NNT was further reduced if the definition of thromboembolism expanded to include ATE and other events (eg, in an analysis of the CASSINI trial, an RCT of rivaroxaban prophylaxis, NNT was 17 for patients with a Khorana score ≥2 with an expanded definition of thromboembolism). Based on these findings, since 2019 most guidelines have been recommending consideration of primary thromboprophylaxis in ambulatory patients with cancer who have a Khorana score of 2 or higher.
JAMA Oncology 2023