Tumours are nowadays the second world‑leading cause of death after cardiovascular diseases. During the last decades of cancer research, lifestyle and random/genetic factors have been blamed for cancer mortality, with obesity, sedentary habits, alcoholism, and smoking contributing as supposed major causes. However, there is an emerging consensus that environmental pollution should be considered one of the main triggers. Unfortunately, all this preliminary scientific evidence has not always been followed by governments and institutions, which still fail to pursue research on cancer's environmental connections. In this unprecedented national-scale detailed study, we analyzed the links between cancer mortality, socio-economic factors, and sources of environmental pollution in Italy, both at wider regional and finer provincial scales, with an artificial intelligence approach. Overall, we found that cancer mortality does not have a random or spatial distribution and exceeds the national average mainly when environmental pollution is also higher, despite healthier lifestyle habits. Our machine learning analysis of 35 environmental sources of pollution showed that air quality ranks first for importance concerning the average cancer mortality rate, followed by sites to be reclaimed, urban areas, and motor vehicle density. Moreover, other environmental sources of pollution proved to be relevant for the mortality of some specific cancer types. Given these alarming results, we call for a rearrangement of the priority of cancer research and care that sees the reduction and prevention of environmental contamination as a priority action to put in place in the tough struggle against cancer.
Almost 180.000 people die every year from cancers in Italy. Although a slightly decreasing trend in northern regions has been observed during the last 20 years and stable mortality in central-southern regions, cancers are nowadays the second world and national leading cause of death after cardiovascular diseases. Breast and lung cancer are the most prevalent forms of neoplasia in women and men, respectively, followed by colon, rectum, prostate, cervix, uterus, stomach, bladder, and other forms. In Italy, lung cancers are causing the highest number of deaths across both sexes (ISTAT 2019).
During the last decades of cancer research, lifestyle and random/genetic factors have been blamed for cancer mortality, with obesity, sedentary habits, alcoholism, and smoking contributing as supposed major causes (Osório-Costa et al., 2009; Khan et al., 2010). Instead, there is an emerging consensus that environmental pollution should be considered one of the main triggers (Bhat et al., 2017; Cazzolla Gatti, 2021). For instance, lung cancer heavily affects also non-smokers: approximately 18,000–27,000 deaths in the world are caused every year by lung cancer in people who are not active cigarette smokers, whose about 20.000 are non-smokers during all life (Thun et al., 2006; Ihsan et al., 2011). Similarly, obesity seems to increase the risk of cancer but does not directly cause it (Deng et al., 2016). Moreover, alcoholism has been identified as a relevant factor in liver cancer induction but it does not represent the only, and it is not the principal, inductor (Cao and Giovannucci, 2016).
In a nutshell, we explored the potential spatial association between socioeconomic and lifestyle factors, many sources of environmental pollutants, and cancer mortality in Italy. Some environmental factors have repeatedly shown their relevance to deaths for multiple forms of cancers. With the findings that emerged from this study, we call for a reconsideration of the priority of cancer research and care that sees the reduction and prevention of environmental contamination as one of the main priority actions to put in place in the tough struggle against tumours. We acknowledge that diet, obesity, and infections are key factors too, and in many cases, these are not related to individual actions but the social class and poverty. However, the genes we inherit and the lifestyle we decide or are forced to adopt may be the sliding doors of a station towards either sickness or wellness, but the quality of the environment we live in is the train where we will spend the journey. If the coach is polluted, our efforts for a comfortable trip could be fruitless (even literally!).