OC 64.1 - Natural history of untreated acute pulmonary embolism in cancer patients: a retrospective cohort of patients with missed pulmonary embolism

Background: Whether it might be appropriate to withhold anticoagulation in cancer patients with small incidental pulmonary emboli (PE) has been a matter of debate.

Aims: Evaluate the natural history of untreated PE in cancer patients.

Methods: CT scans using intravenous contrast and including the chest were identified from 1/1/2019 through 12/31/2019 and were analyzed using artificial intelligence (AIDoc) for PE. Natural language processing identified reports with clinically detected PE. All cases determined positive for PE by AIDoc without reported findings of PE were reviewed (including a random sample of 1400 cases) by a thoracic radiologist to validate the presence of missed acute PE.

Results: Out of 14,453 CT scans, 41 patients with malignancy were found to have missed PE (24 segmental and 17 subsegmental) that was not clinically identified and went untreated. Seventeen types of cancers were represented: pancreatic (14%), breast (12%), esophageal (10%), ovarian (10%), and renal (10%) being the most common types. In those not treated, subsequent chest imaging was performed in all but nine patients. The median time of follow-up was 243 days with a range of 0-1153. In the 32 patients with follow-up chest imaging, the initial PE resolved entirely in 30 and resolved partially in 2. Seven (17%) patients had imaging confirmed recurrent PE (all in patients with resolution of the initial PE), Figure. Two (12%) were in patients with initial subsegmental PE, and 5 (21%) in patients with initial segmental PE (Fisher’s Exact Test p value=0.67). The median time to recurrent PE was 291 days (range 54-952).

Conclusion(s): In this cohort of missed and untreated PE in cancer patients, the risk of recurrent PE was high even in the setting of small (segmental/subsegmental) PE.