For the first time, it has been mapped out where the risk of dying from cancer is greatest in the Iberian Peninsula. This has yielded special insights into similarities between Spain and Portugal but also revealed remarkable differences.
For example, it seems breast, esophagus, and throat cancers are most common in the border area between Spain and Portugal. But this geographical similarity is not there in the case of lung, prostate, and stomach cancer. This is the result of a joint study by the National Centre for Epidemiology in Madrid and the National Institute of Public Health in Lisbon.
The study looked at the probability of dying from one of the ten types of cancer per municipality. For this purpose, 840,000 causes of death were analysed. These were registered between 2002 and 2012. When determining the risk percentages, the demographic characteristics of the municipalities were taken into account. Therefore, the percentages are not based on absolute numbers but have been adjusted to the standard demographics. Below is a geographical overview of the 5 cancers that cause the most deaths.
In both Spain and Portugal, lung tumor is number one when it comes to the absolute number of cancer deaths. A clearly increased risk can be seen especially in Spain. This is in the western part of Andalucia and Castile-La Mancha and throughout Extremadura, especially among men. In Spain, more than 23% of men smoke daily versus 16% of women. Most smokers can be found in the Extremadura region. According to a 2020 study, one in four residents smokes here daily. In the province of Badajoz, the risk of dying from lung cancer is therefore almost twice as high as in the province of Segovia. The risk of dying from lung cancer is remarkably low in Portugal. This is related to the fact that 20% of adult Spaniards smoke versus 11% of Portuguese.
The risk map shows a clear risk area for death from breast cancer (only looking at breast cancer in women) in southwestern Spain and southern Portugal. Factors that increase this risk include smoking, hormone therapies during menopause, and some types of birth control pills. Obesity and alcohol consumption also increases the risk of breast cancer. However, the increased risk in the southwestern part of the peninsula may also be related to poorer health care facilities. The survival rate for breast cancer is above 85%. So it could be that cancer care is less accessible in the risk area mentioned. The chance of dying from breast cancer is more than twice as high in the provinces of Huelva and Cádiz as in Guadalajara.
Remarkably, the risk of dying from prostate cancer is significantly higher for men in Portugal than for men in Spain. In Spain, there is only an increased risk in a number of municipalities in Asturias, Aragón, Valencia, and Galicia, while almost the entire map of Portugal is colored red. The researchers suspect that a genetic factor plays a role in this. Nor can it be ruled out that an unknown factor in the processing of statistical data prevents a correct interpretation of the results.
When it comes to the risk of dying from esophageal cancer, the border between Spain and Portugal has blurred again. An increased risk is especially seen in northwestern Spain and northern Portugal, especially in men. The researchers also explain this by the fact that men smoke more often than women and drink more alcohol. Overweight, obesity and a poor diet can also increase the risk of esophageal cancer. For Mediterranean area residents, the chance of dying from esophageal cancer is significantly lower, possibly due to a healthier diet.
For residents of Portugal, the chance of dying from stomach cancer is significantly higher than for the Spaniards. In Spain, stomach cancer is in seventh place when it comes to most fatalities, in Portugal this form of cancer is number three. Particularly in the north of Portugal, relatively many people die of stomach cancer.
On the map of Spain, the red area is limited to the innermost part of the Castile and León region. According to the researchers, infection with the Helicobacter pylori bacterium plays a role in the development of stomach cancer. This bacterium enters the body through drinking water or foods.
More than half of Spaniards carry this bacterium, but an infection with the Helicobacter pylori bacterium leads to a stomach tumor in only a very small percentage. There is no clear explanation for the difference in risk between Spain and Portugal, but the faster development of Spain may play a role. Research shows that stomach bacteria are more common in countries that have developed later. It has been shown that a diet with a lot of processed food and few vegetables is related to the development of stomach cancer.
Mapping the risk of dying from cancer in the Iberian Peninsula started as early as 2015, but was delayed by the onset of the pandemic. Now that this phase has been completed in Spain and Portugal, the research is being expanded to neighbouring France in order to map an increasingly larger area.