Pulmonary Embolism Diagnostic Challenges in Oncology

The diagnostic management of pulmonary embolism in patients with active malignancy remains a complex challenge for clinical practice. Oncology patients often present with non-specific symptoms such as dyspnea and tachycardia, which frequently overlap with cancer complications or treatment side effects. Traditionally, clinicians have relied heavily on computed tomographic pulmonary angiography (CTPA) because conventional decision rules and standard D-dimer thresholds are perceived as less reliable in this high-risk population. However, excessive use of CTPA introduces risks, including radiation exposure and contrast-induced nephropathy. Consequently, the publication of the Hydra study in JAMA provides a timely evaluation of the YEARS algorithm pulmonary embolism diagnostic strategy for cancer patients. This randomized trial sought to determine if a simplified approach could safely reduce the necessity for invasive imaging. By integrating specific clinical criteria with adjusted D-dimer levels, the YEARS algorithm aims to provide an efficient triage system. Therefore, understanding this study is essential for oncologists striving to balance diagnostic safety with patient-centered care.

Design and Methodology of the Hydra Clinical Trial

The Hydra study was an open-label, randomized, non-inferiority trial conducted across 21 hospitals in Europe. Researchers recruited 698 patients with active cancer and suspected acute pulmonary embolism between 2019 and 2025. Participants were randomly assigned in a 1:1 ratio to diagnostic management through the YEARS algorithm or the standard CTPA-only protocol. Specifically, the YEARS group underwent assessment based on three clinical items and variable D-dimer thresholds. In contrast, the control group proceeded directly to CTPA, reflecting current standards. The median age was 65 years, and 60% were female, providing a representative sample of oncology patients. Notably, the study utilized blinded central adjudication to ensure primary outcomes remained objective and robust. Furthermore, the 90-day follow-up allowed for a comprehensive assessment of symptomatic venous thromboembolism or PE-related deaths. As a result, the findings carry significant weight for oncology guideline revisions and daily decision-making. Therefore, these results suggest a shift in how we approach suspected embolic events in clinical oncology.

Understanding the YEARS Algorithm and D-dimer Thresholds

Central to this strategy is the YEARS algorithm pulmonary embolism assessment, which simplifies decisions into three clinical components. These include clinical signs of deep vein thrombosis, hemoptysis, and the judgment on whether pulmonary embolism is the most likely diagnosis. Unlike models that use a fixed D-dimer cutoff, YEARS employs a dynamic threshold based on these markers. For instance, if a patient has zero YEARS items, the D-dimer threshold is elevated to 1000 ng/mL. Conversely, if items are present, the threshold is 500 ng/mL. This approach acknowledges that baseline D-dimer levels are often chronically elevated in cancer due to inflammation. Consequently, using a higher threshold for low-risk patients allows for a specific rule-out process without sacrificing sensitivity. Moreover, this streamlined two-step pathway is easier to implement in busy clinical environments. Therefore, by adjusting laboratory cutoffs to clinical probability, physicians can better identify patients who truly require imaging while avoiding unnecessary tests for those at lower risk.

Safety and Noninferiority of the YEARS Algorithm Pulmonary Embolism Strategy

The primary outcome of the Hydra study focused on the safety and noninferiority of the YEARS algorithm pulmonary embolism strategy over 90 days. Specifically, the trial measured the incidence of symptomatic venous thromboembolism or PE-related death in patients where the initial diagnosis was ruled out. Results demonstrated that the YEARS group was non-inferior to the CTPA-only group. In the per-protocol analysis, the primary outcome occurred in only 1.8% of the YEARS group compared to 5.5% in the CTPA-only group. This yielded an absolute risk difference of -3.7%, falling comfortably within the predefined non-inferiority margin. Furthermore, intention-to-diagnosis analysis mirrored these results, showing a risk difference of -2.6% with high statistical significance. These findings suggest the algorithm does not miss clinically significant embolic events compared to standard imaging. Additionally, the safety profile remained consistent across various malignancies and age groups. Thus, clinicians can feel confident that utilizing YEARS criteria does not compromise patient safety or diagnostic accuracy in oncology.

Efficiency Gains and Reduction in Computed Tomographic Angiography

Beyond safety, the efficiency of the YEARS algorithm pulmonary embolism diagnostic pathway was a key secondary measure. The study found that 22% of patients in the YEARS group ruled out pulmonary embolism without CTPA. Specifically, 77 out of 352 patients avoided imaging because they met the algorithm's rule-out criteria. While negative CTPA proportions did not differ significantly between groups, the total scan volume was substantially lower in the YEARS cohort. This reduction is clinically significant, as one in five cancer patients can be spared from radiation and contrast. Moreover, avoiding unnecessary scans can lead to shorter hospital stays and reduced healthcare costs. It also mitigates the risk of incidental findings, such as sub-segmental emboli of uncertain significance, which often lead to over-treatment. Consequently, these efficiency gains represent a major step toward sustainable diagnostic protocols. Therefore, the Hydra study successfully demonstrates that a selective imaging strategy is feasible and beneficial for oncology patients.

Integrating YEARS into Routine Clinical Oncological Management

Implementation of the YEARS algorithm into routine care for cancer patients requires a shift in mindset. Previously, active malignancy was considered an automatic indication for imaging when PE was suspected. However, the Hydra trial supports a more nuanced approach. Clinicians should start by assessing the three YEARS items and obtaining a D-dimer level. If a patient is stable and meets rule-out criteria, imaging can be safely omitted. This change could benefit patients with renal impairment or those with high cumulative radiation exposure. Furthermore, institutions should update internal protocols to prompt for YEARS criteria when a PE workup is initiated for oncology patients. Nevertheless, it is important to remember that the algorithm is intended for hemodynamically stable patients. If there is high clinical concern or hemodynamic instability, immediate imaging remains paramount. Overall, the integration of YEARS criteria offers a balanced, evidence-based approach to a common diagnostic dilemma, significantly improving patient outcomes and resource utilization in oncology.

Frequently Asked Questions

What are the three specific items used in the YEARS algorithm?

The YEARS algorithm is a clinical decision tool designed to simplify the diagnostic workup for suspected pulmonary embolism. It consists of three items: clinical signs of deep vein thrombosis, hemoptysis, and the assessment of whether PE is the most likely diagnosis. By combining these criteria with two different D-dimer thresholds—1000 ng/mL for patients with zero items and 500 ng/mL for those with one or more—clinicians can safely rule out PE without imaging.

Why was a specific study necessary for cancer patients using this algorithm?

Cancer patients were previously excluded from many clinical rule-out studies because they often have chronically elevated D-dimer levels and a high baseline risk of thrombosis. Most guidelines suggested proceeding directly to CTPA for this population. However, the Hydra study was specifically conducted to provide evidence that the YEARS algorithm works safely in oncology. It proves that clinicians do not need to rely solely on CTPA and can instead use D-dimer thresholds adjusted for clinical probability.

What were the main safety findings of the Hydra study regarding YEARS?

The Hydra study demonstrated that the YEARS algorithm is as safe as the CTPA-only approach, with a non-inferior rate of missed thromboembolic events within 90 days. In fact, the rate of symptomatic VTE was lower in the YEARS group than in the group that underwent mandatory imaging. Furthermore, the algorithm safely reduced the number of unnecessary CTPA scans by 22%, thereby protecting patients from the risks associated with radiation and intravenous contrast material.

Disclaimer: This content is for informational and educational purposes only and does not constitute medical advice. It is not a substitute for professional clinical judgment, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

Akerboom B et al. YEARS Algorithm for Diagnosis of Suspected Pulmonary Embolism in Patients With Cancer: A Randomized Clinical Trial. JAMA. 2026 Jul 12. doi: 10.1001/jama.2026.10676. PMID: 42437322.

van der Hulle T, et al. Simplified diagnostic management of suspected pulmonary embolism (the YEARS study): a prospective, multicentre, cohort study. Lancet. 2017;390(10091):289-297.

Konstantinides SV, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020;41(4):543-603.