Prognosis of incidental pulmonary embolism vs. symptomatic pulmonary embolism in cancer patients: a single-center retrospective cohort study in China

BACKGROUND: The incidence of incidental pulmonary embolism (IPE) has greatly increased, but its clinical characteristics and outcomes are still controversial. This study aimed to compare the clinical characteristics and outcomes between cancer patients with IPE and patients with symptomatic pulmonary embolism (SPE). PATIENTS/METHODS: Clinical data of 180 consecutive patients with cancer complicated with pulmonary embolism admitted to Beijing Cancer Hospital from July 2011 to December 2019 were retrospectively collected and analysed. General characteristics, diagnosis time of pulmonary embolism (PE), location of PE, concurrent deep venous thrombosis, anticoagulant treatment, impact of PE on anti-tumor treatment, recurrent venous thromboembolism, rate of bleeding after anticoagulation therapy, survival and risk factors of IPE were compared with SPE. RESULTS: Of 180 patients, 88 (49%) had IPEs and 92 (51%) had SPEs. Patients with IPE and SPE did not differ in age, sex, tumor type, or tumor stage. Median diagnosis times of IPE and SPE after cancer were 108 (45, 432) days and 90 (7, 383) days, respectively. Compared to SPE, IPE tended to be central (44% versus 26%; P < 0.001), isolated (31.8% versus 0.0%; P < 0.001), and unilateral (67.1% versus 12.8%; P < 0.00). The rate of bleeding after anticoagulation therapy did not differ between IPE and SPE. Patients with IPE had a better prognosis than patients with SPE in terms of 30-, and 90-day mortality, as well as overall survival after diagnosis of PE (median: 314.5 vs. 192.0 days, log-rank P = 0.004) and cancer (median: 630.0 vs. 450.5 days, log-rank P = 0.018). SPE (compared to IPE) was an independent risk factor for poor survival after diagnosis of PE in multivariate analysis (hazard ratio [HR] = 1.564, 95% confidence interval [CI]: 1.008–2.425, p = 0.046). CONCLUSIONS: IPE accounts for nearly one half of PE cases among Chinese cancer patients. With active anticoagulation treatment, IPE is expected to achieve better survival rates than SPE.