The YEARS algorithm can rule out pulmonary embolism (PE) when applied to patients with cancer, reducing the need for CT pulmonary angiography in 22% of patients.
The findings, from a study published in JAMA and presented at the International Society on Thrombosis and Haemostasis (ISTH) 2026 Congress, provides a path forward to reducing the costs, length of ED stay, and exposure to ionizing radiation and contrast associated with CT pulmonary angiography (CTPA).
“To our knowledge, this study is the first randomised trial to compare a validated diagnostic algorithm to rule out acute PE with management using CTPA only specifically in patients with active cancer,” the study said.
The Hydra study comprised 698 adults with active cancer other than keratinocyte cancer and a clinical suspicion of acute PE recruited from 21 hospitals in six European countries. They were randomised to either diagnostic management by the YEARS algorithm or diagnostic management by CTPA only.
The YEARS algorithm combines three clinical items determined by the treating physician then a D-dimer. If a patient had none of the YEARS items, PE was excluded if the D-dimer was <1000 ng/mL. If the patient had ≥1 YEARS items, PE was excluded if the D-dimer was <500 ng/mL. In all other circumstances, a CTPA was performed according to standard local clinical practice.
The study found the primary outcome of objectively proven, symptomatic PE, symptomatic upper or lower extremity deep vein thrombosis (DVT) or (possible) PE-related death during the 90-day follow-up period occurred in 1.8% of the per-protocol YEARS group and 5.5% in the CTPA only group (absolute risk difference, −3.7%; 99.9% CI, −8.8% to 1.4%; P = 3.4 × 10−5 for noninferiority).
The study found 22% of patients were managed without CTPA.
“The number of negative CTPA results as a proportion of the total number of CTPA performed at the initial testing of patients randomised to the YEARS algorithm was not different from that in patients randomized to the CTPA-only approach (83% vs 83%, P = .93 for superiority).”
The 3-month all-cause mortality was 21% in both the YEARS group and the CTPA-only group.
“The results of this noninferiority trial demonstrated that the YEARS diagnostic algorithm is as safe as CTPA only in excluding PE in patients with cancer with a low risk of VTE during a 3-month follow-up.”
The investigators said their study fills a gap between initial evaluation of the YEARS algorithm in the general population [link here] in which 48% of the cohort did not require CTPA to exclude PE.
They said even though the majority of patients with cancer and suspected PE will still have to undergo CTPA, the use of the YEARS algorithm will substantially reduce the total number of CTPAs performed.
An accompanying editorial in the journal [link here] said the 2026 American Heart Association/American College of Cardiology (AHA/ACC) guideline for acute PE endorses clinical decision tools, including the YEARS algorithm as safe ways to reduce imaging of patients with low to intermediate pretest probability.
However its use in patients with cancer was previously undefined.
“The Hydra study addresses this gap. The trial enrolled patients with localised, regional, and metastatic cancer across many tumour types.The result establishes that CT pulmonary angiography for all, while safe, is not the only reasonable approach.”
They said there are now two priorities.
“First, the YEARS algorithm should be validated within cancer-specific subgroups, given that 12-month VTE incidence ranged from approximately 1% in patients with prostate cancer to more than 12% in patients with pancreatic cancer,” they said.
“Second, cancer-specific D-dimer thresholds warrant further investigation. Baseline D-dimer levels may vary by tumor type and stage, which lowers the specificity of a fixed threshold in metastatic disease.