Crude cancer mortality rate and global kinetics of the SARS-COV2 pandemic
James Fleck: Anticancerweb 17(05), 2020
The crude mortality rate is the total number of deaths from a specific disease in a defined geographical area, divided by the total population in the same geographical area and multiplied by 100,000. Global Cancer Observatory is an interactive web platform that collects data from 185 countries or territories covering the 36 most frequent types of malignant disease. Data is provided by the International Agency for Research on Cancer (IARC), an intergovernmental agency, part of the World Health Organization (WHO). The data are mainly supported by population-based cancer registries and crude mortality rate is a very useful criterion for estimating global cancer burden. As the epidemiological data are retrospective, the most recent report corresponds to the year 2018. Based on this data, worldwide incidence and mortality from lung cancer are 2,093,876 and 1,761,007 respectively, leading to a crude incidence rate of 27.4 / 100,000 inhabitants and a crude mortality rate of 23.1 / 100,000 inhabitants. Lung cancer is the leading cause of death for malignant diseases in the world. Assuming that small-cell lung cancer (SCLC) accounts for 15% of total lung cancer incidence, it is possible to estimate 314,081 new cases of SCLC each year worldwide. As the overall SCLC mortality rate is 94%, there is an estimated 295,236 deaths attributed to SCLC worldwide each year. Coincidentally, the data provided by the Center for Science and Systems Engineering at John Hopkins University at May 15th, 2020 3:30 PM, showed 305,395 deaths attributed to COVID-19, in the world. Very close numbers, which means that SARS-COV2 in just three months has already caused an absolute number of deaths greater than the current number of annual deaths due to SCLC, considered one of the most aggressive and lethal neoplasms. The US has the highest number of confirmed cases of COVID-19 (May 16, 2020 at 15:30 PM = 1,429,990), which is related to 86,744 deaths. The current US population is 330,753,490 inhabitants. Using only US data, it is possible to estimate a crude COVID-19 mortality rate of 26.23 / 100,000 inhabitants in the last three months, already higher than the global crude mortality rate for all types of lung cancer, reported by IARC (23.1 / 100,000 inhabitants). In the USA, breast cancer is the main malignant disease in women, with a crude mortality rate of 25.4 / 100,000. That number has also been exceeded by COVID-19 crude mortality rate, observed in the past three months. The attached table shows epidemiological data for the ten countries with the highest incidence of COVID-19 in the world. It shows that the estimated crude mortality rate due to COVID-19 for each country is very close to that reported for a specific type of malignant tumor.
CMR = Crude Mortality Rate
This is just a mathematical equation, since both the data are presently underestimated in the world. Since population-based cancer registry does not have the same population coverage around the world, the reported incidence and mortality rate are just an estimate. Similarly, COVID-19 data provided by John Hopkins also shows great discrepancy in the estimated crude incidence and mortality rates in different countries. Data heterogeneity could be explained by unsynchronized disease onset or countries’ inequality in the adoption of preventive and protective measures. Discrepancies could be magnified by the rapid clinical course of COVID-19, associated to an uneven distribution of RT-PCR tests around the world. Additionally, a large number of patients are oligosymptomatic or no symptomatic at all. These limitations create difficulties for the precise identification of fraction numerator. However, despite methodological limitations, COVID-19 has already reached a death rate similar to that presented by different types of malignant tumors worldwide.
References:
1. International Agency of Research on Cancer (IARC): Cancer Today, 2018
Link: https://gco.iarc.fr/today/online-analysis-table
2. Center for Science and Systems Engineering at John Hopkins University, 2020
Link: https://www.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6
3. Photo by CDC on Unsplash (modified)
The number of cases of death caused by covid-19 can be comparable to the number of deaths caused by the main types of carcinoma. Several studies have shown that this new disease has had a major impact on society. It is known that the number of deaths caused by cancer in the world is very large and when we are faced with data that match those caused by sars-cov-19 it shows us the magnitude of the problem we are experiencing. However, we know exactly how to avoid contagion by sars-cov-19, unlike what happens with many types of cancer, in that way we must protect ourselves as a society, thinking about the common good. Thus, protective measures and social isolation must be strictly follow, because it is known that this disease is causing an amount of deaths comparable to those of carcinomas.
COVID-19 infection has shown high lethality in a very short time. Although most people are asymptomatic, those who need hospitalization and consequently the ICU often end up not resisting the damage caused by the infection. Therefore, unfortunately, it was expected that such a disease would equal in numbers to several other comorbid ones, such as the SCLC.
This article shows that cancer and COVID-19 by themselves cause a great number of deaths. But we have to remember that the SARS- CoV-2 pandemic affects not only the patients infected by the virus, but also changes the way patients with chronic diseases manage and face their comorbities. For example, patients with cancer have the need for increased surveillance and testing for SARS-CoV-2, because they appear to be at increased risk of mortality and severe illness due to COVID-19 infection, regardless of whether they have active cancer, are on anticancer treatment, or both. Therefore, the crude mortality rate doesn't necessarily show the real impact of the pandemic worldwide.
For sure the data presented in this article reinforce the devastating effects of SARS-CoV-2 infection since its death rates are comparable to those of leading causes of mortality worldwide (such as lung cancer). [1] Besides the fact that the deaths caused by COVID-19 are still increasing daily, I believe that the impact of this condition will go far beyond the mortality caused specifically by SARS-CoV-2 infection. We must consider the indirect consequences of the pandemic scenario, such as the high number of patients left untreated due to the interruption of their follow-up in outpatient care. 1. Collaborators, G.B.D.C.o.D., Global, regional, and national age-sex-specific mortality for 282 causes of death in 195 countries and territories, 1980-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet, 2018. 392(10159): p. 1736-1788.
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