Eduard Teixidor
Assistant doctor of medical oncology at the Catalan Institute of Oncology and at the Girona University Hospital Doctor Josep Trueta
Rafael Marcos Gragera
Epidemiologist at the Catalan Institute of Oncology and professor of medicine at the University of Girona
The presented study seems to be a good review and analysis of available mortality data from the World Health Organisation (WHO). Such studies are useful and necessary to assess the long-term control of chronic diseases.
Despite the subjective feeling we have on the street, the trend in cancer mortality is decreasing. Although in absolute values one would say that mortality is increasing, when adjusted for the characteristics of the current population (mainly age), the graphs show a decrease in mortality as described in this study.
In Spain, lung cancer is the second cancer with the highest incidence in men and the third in women, and it is the first in number of cancer deaths in both sexes combined.
With regard to the gender differences in lung cancer mortality, although not surprising, it is interesting to note once again that in southern European countries lung cancer mortality in women is increasing while the trend in men continues to decrease. This translates into a higher number of deaths than initially expected in women and a reduction in men.
Smoking is most likely the main factor behind this. Tobacco use is the leading cause of lung cancer worldwide, and the risk is related to both the intensity and duration of smoking. Tobacco use has also been associated with the development of 14 other tumour types so far. Other risk factors for this disease include exposure to indoor radon and occupation.
In Spain in particular, the differences in the evolution of smoking prevalence between the sexes are reflected in the mortality attributed to smoking, which has a downward trend in men and is currently still increasing in women. In addition, the increase in the burden of lung cancer mortality attributed to tobacco use in women is noteworthy, from 12.3% of total smoking-attributed mortality in the period 1990-2003 to 21% between 2004-2018. In men, smoking has been declining since the 1980s, when prevalence figures in 1987 were 55.1 %; in women, prevalence figures started to decline much more recently, in 2001, when 27.3 % of Spanish women smoked.
On the other hand, the feasibility of screening programmes (early detection) for lung cancer has been discussed in recent years. The recommendations contained in the European Strategy Against Cancer (2022) and the update of the 2003 European recommendations approved in 2022 maintain the convenience of population screening for breast cancer, colorectal cancer and cervical cancer, while mentioning the convenience of studying and carrying out pilot studies that contribute to clarifying questions that are still unresolved with regard to the implementation of new cancer screening programmes for the early diagnosis of lung cancer, prostate cancer and stomach cancer.
The early detection of lung cancer requires a CT scan, but there is still uncertainty about the frequency with which this test should be performed, and about the protocols that should be followed when certain lesions are diagnosed. For this reason, different pilot projects are being carried out in Spain to evaluate certain technical aspects of the protocols that should be established. In addition, the feasibility of including this screening in the National Health System's service portfolio must be studied in detail, establishing the technical and human resources that would be necessary for its development.
Compared with the cancer screenings currently included in the service portfolio of the Autonomous Communities (breast, cervical and colorectal), lung cancer is the only one that targets a disease 85 % of which is preventable if action is taken against tobacco consumption (its main risk factor), This highlights the need for action and implementation of the WHO's MPOWER strategy or even beyond, as proposed by the ENDGAME strategy, which aims to achieve a tobacco-free society.
Working on interventions based on primary prevention of tobacco use makes the most sense, as it not only reduces the risk of lung cancer but also of other tumours, cardiovascular diseases and respiratory diseases in both smokers and those exposed to environmental tobacco smoke. Therefore, strategies against this disease, which causes more than 25,000 deaths a year in Spain, should be prioritised by PUBLIC HEALTH actions aimed at preventing the initiation of tobacco consumption and encouraging smokers to quit. For ex-smokers, studies carried out in the United Kingdom have shown that it is possible to reduce the late stages of diagnosis with information campaigns for the population (Be aware on cancer).
Taking into account the data published in this article, specifically for Spain, we must also highlight the decrease in mortality in men for all the tumours studied. Specifically, the decreases in mortality from pancreatic, lung and bladder cancer could be attributed to the decrease in the prevalence of smoking in men and, in general, to improvements in treatments (surgery, chemotherapy, target therapies and radiotherapy).
In women, however, the news is not so good: an increase in mortality continues to be observed in tobacco-related tumours such as lung and pancreas. In contrast, we also observe a decrease in mortality in tumours with a high prevalence in women, such as breast and colon cancer, due in part to early detection programmes and improvements in treatment.
Reviewing such a large amount of epidemiological data gives us the opportunity to generate hypotheses and then try to analyse possible influencing factors. Smoking cessation and health protection programmes, especially those related to smoking and occupational exposure, are helping to reduce mortality. Improvements in treatment are also expected to have a significant impact in the near future.
Regarding the limitations of the study, the different tools for data collection should always be taken into account as a limitation when making cross-country comparisons. Another limitation, in terms of mortality projections, as described in the discussion, is that they could be affected by the influence of the COVID pandemic.
It would be desirable in the future to be able to conduct this type of study at the EU level with incidence data. Analysing mortality data is useful, but it does not reflect the true impact of cancer on the population; it would be necessary to have incidence data that also includes information on those patients who survive cancer. In order to carry out incidence studies, it would be necessary to have an information system on cancer incidence that covers the entire Spanish population. At present, only 26% of the population in Spain is covered by population-based cancer registries.