To the Editor:
In a recent article published in CHEST (March 2021), Jiménez et al1 conducted a systematic review about the current evidence on the incidence of venous thromboembolic events (VTE) among hospitalized patients with COVID-19. In this article, 48 observational studies were reviewed, detecting an overall incidence of VTE of 17.0%. This incidence was higher in prospective studies including thrombosis screening (33.1% vs 9.8% in clinical diagnosis) and patients admitted to the ICU compared with those admitted to the ward (27.9% vs 7.1%, respectively). In this review, 24% of the total population included in all studies were cancer patients. However, throughout the article there is no reference to this patient subgroup being the most affected by COVID-19.2 Further sub-analysis was made that allows us to understand what consequences could have a more prothrombotic state in patients with an already greater risk of developing VTE.
Cancer patients have inherently 4 to 7 times the risk of developing VTE.3 As described by Bakouny et al,4 there is no clear evidence of increased thrombosis in cancer and COVID-19. However, even though there are no studies to support it, they conclude that VTE diagnoses in these patients are probably being underestimated because of strong evidence of a cancer procoagulant state.4 Nevertheless, in the only study published with cancer patients diagnosed with COVID-19, the incidence of thrombosis was not increased in oncological patients. Patell et al5 detected a cumulative incidence of VTE of 18.2% in the non-cancer cohort and 14.2% in the cancer cohort.5 Survival was significantly shorter in the group with active cancer (P = .038), but, surprisingly, the cumulative incidence of major and fatal bleeding was similar, 20.8% in the non-cancer group and 19.5% in the cancer cohort.5
Therefore, a great question must be answered: Is there really a procoagulant summation effect between cancer and COVID-19? We hypothesized that when cancer patients develop the COVID-19 cytokine storm that could generate VTE, these patients are already in a critical situation with a high mortality (in our series approximately 40%), probably dying without time enough to develop thrombosis,2 or they may be underdiagnosed in those critically ill patients with a very bad prognosis, especially in the first weeks of the pandemic. These points might be the reasons for a lower cumulative incidence of VTE in cancer patients.
Acknowledgments
Author contributions: J. R. contributed to the conception and design of the study, data acquisition, statistical analysis, interpretation of the data, and writing of the manuscript. B. O., N. M. R., and M. A. L. contributed to the conception and design of the study and interpretation of the data. All authors reviewed and approved the final version of the manuscript.
∗ Infanta Leonor Thrombosis Research Group Collaborators: B. Mestre-Gómez, MD; R. M. Lorente-Ramos, MD; J. Rogado, MD; A. Franco-Moreno, MD, PhD; B. Obispo, MD; D. Salazar-Chiriboga, MD; T. Saez-Vaquero, MD, PhD; J. Torres-Macho, MD, PhD; A. Abad-Motos, MD, PhD; C. Cortina-Camarero, MD; A. Such-Diaz, PhD; E. Ruiz-Velasco. MD; N. Muñoz-Rivas, MD, PhD; F. Sierra-Hidalgo, MD, PhD; E. Moya-Mateo, MD; M. de Carranza-López, MD; M. A. Herrera-Morueco, MD; M. Akasbi-Montalvo, MD; V. Pardo-Guimerá, MD; P. Medrano-Izquierdo, MD; E. Mariscal-Gómez, MD; K. Marín-Mori, MD; C. Figueras-González, MD; S. López-Lallave, MD; D. Díaz-Díaz, MD; C. Mauleón-Fernández, MD; J. Martín-Navarro, MD; P. Torres-Rubio, MD; C. Matesanz, MD; M. J. Moro-Alvarez, MD; A. Bustamante-Fermosel, MD; J. A. Hernández-Rivas, MD, PhD.
Footnotes
Drs Rogado and Obispo contributed equally to this manuscript.
FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.
Contributor Information
Infanta Leonor Thrombosis Research Group:
B. Mestre-Gómez, R.M. Lorente-Ramos, J. Rogado, A. Franco-Moreno, B. Obispo, D. Salazar-Chiriboga, T. Saez-Vaquero, J. Torres-Macho, A. Abad-Motos, C. Cortina-Camarero, A. Such-Diaz, E. Ruiz-Velasco, N. Muñoz-Rivas, F. Sierra-Hidalgo, E. Moya-Mateo, M. de Carranza-López, M.A. Herrera-Morueco, M. Akasbi-Montalvo, V. Pardo-Guimerá, P. Medrano-Izquierdo, E. Mariscal-Gómez, K. Marín-Mori, C. Figueras-González, S. López-Lallave, D. Díaz-Díaz, C. Mauleón-Fernández, J. Martín-Navarro, P. Torres-Rubio, C. Matesanz, M.J. Moro-Alvarez, A. Bustamante-Fermosel, and J.A. Hernández-Rivas
References
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