Alejandro Pérez Fidalgo
Medical doctor in the Oncology and Haematology Department at the Valencia Clinical Health Research Institute (INCLIVA), Valencia Clinical Hospital
Is the study based on solid data and methods?
"The study is relevant and its conclusions are important, as it has analysed a huge amount of data by cross-referencing different databases. On the one hand, they analyse the incidence of new diagnoses of different types of cancer by country, age and gender using the GLOBOCAN database; and, on the other hand, they use several databases on the prevalence of known cancer risk factors, including those from the WHO, IARC and UNICEF, from which they extract the risk of exposure to the different known risk factors in that age group, country and gender. By cross-referencing the databases, they can establish which cancers could be prevented by country and gender.
Therefore, the study has a weakness in that it does not establish a cause-and-effect relationship, but rather uses known factors to establish a correlation between cancer prevalence and the proportion of risk factors 10 years earlier in that population.
Given the large number of tumours included—18.7 million, of which 7 million are attributable to preventable cancers—and the power of the databases used, the conclusions can be considered sufficiently robust."
How does it fit in with previous work? What new information does it provide?
"The study highlights the importance of preventable risk factors such as tobacco, infections and others in the development of cancer in the population. What I would highlight about this work is that it quantifies it in figures and that these are really compelling. For example, it clearly highlights tobacco as the leading cause of cancer in men, attributing no less than 23.1% of all cancers in men in 2022 to this cause. This gives us an idea that anti-smoking campaigns or smoking prevention efforts could have a huge impact on cancer control.
The data is equally relevant in the case of women, for whom infections are the main cause of cancer, specifically the papilloma virus (for cervical cancer) and Helicobacter pylorii for gastric cancer. 11.5% of cases could be due to exposure to these agents.
This is very important for designing, justifying and even intensifying efforts in vaccination campaigns against the papilloma virus. This also has greater or lesser consequences depending on geographical location."
Are there any important limitations to consider?
As I mentioned before, the biggest limitation is that it is not a cause-and-effect or case-control study, but rather an epidemiological study in which prevalence data is cross-referenced with exposure to known risk factors by sex, age and country. Despite this limitation, I believe the study is thought-provoking and should be taken into consideration."
How relevant is this study to clinical practice in Spain? What recommendations can we make based on it?
"Given that these are epidemiological data, the greatest applicability is that it clearly quantifies, in a more or less approximate way, the true impact of not taking measures to prevent cancer. Maintaining high levels of exposure to risk factors has consequences. 7.1 million consequences (preventable cancer) in 2022 worldwide.
But it also allows health authorities to be guided as to which countries, genders and locations this lack of prevention has the highest cost.
On the other hand, this quantification is important because it allows us to justify that prevention strategies have an impact on the population and can also be cost-effective, since preventing 7 million cancers by modifying exposure to risk factors not only improves the health of your population, but also significantly reduces healthcare costs."