Lung cancer is the second most common cancer and the most common cause of cancer death in Belgium and Europe among men. The dominant role of cigarette smoking in lung cancer occurrence has been well established. Yet, the strength of the association between cigarette smoking and lung cancer varies by specific subtype (histology): the association is strongest for small-cell lung carcinoma (SCLC) and squamous cell carcinoma (SCC), cancers that occur in the central bronchi that are more heavily exposed to tobacco smoke, and less strong for adenocarcinoma (ADC) that arise from peripheral sites.
Previous studies have already proven the association between socioeconomic position (SEP) and lung cancer, yielding higher incidence and mortality among the most deprived groups. What has not been mapped out however is whether lung cancer incidence also varies by migrant origin. Previous European and Belgian reports have already demonstrated a migrant mortality advantage for lung cancer in Belgium and Europe but the question remains whether there is variation in lung cancer incidence by migrant origin; for which histological subtypes; and whether this association might be explained by socioeconomic variables.
Katrien Vanthomme and Hadewijch Vandenheede from Interface Demography (VUB) and the Belgian Cancer Registry joined forces to probe into this topic. To do so, they selected to study Belgium as the migrant community is rather large and lung cancer is a very common disease. They made use of individually-linked data containing socioeconomic information in 2001 linked to all lung cancer diagnoses between 2004-2013 as well as mortality during this follow-up. Using these data, the authors were able to calculate absolute and relative lung cancer incidence inequalities by histological subtype for migrant men of Italian, Turkish and Moroccan descent aged 50-74 years as compared to native Belgian men within the same age group.
The findings of this study showed that there is indeed variation in lung cancer incidence by histological subtype and migrant origin. Moroccan men consistently had lower overall and histology-specific lung cancer incidence rates compared to native Belgian men. This advantage was in particular outspoken for the subtypes that are strongly related to cigarette smoking. This suggests that their lower levels of tobacco consumption entail a protective effect against lung cancer incidence. Turkish men on the other hand did not show this advantage and had similar lung cancer incidence patterns to native Belgians, in particular for the smoking-related subtypes. This was not surprising as the level of tobacco consumption in both groups is rather similar. Italian men, in contrast, showed higher lung cancer incidence, in particular for ADC, which is the subtype that is least associated with smoking and for which the full aetiology is still unknown. The authors suggest that this might also be related to the labour history of Italian migrant men, who used to often work in mines, involving exposure to carcinogenic radon.
Furthermore, the authors observed that adding SEP to the models, especially educational attainment, proved to be an important explanatory factor for incidence inequalities by migrant origin. Especially for the smoking-related subtypes, education was important, which reflects differences in health literacy, being receptive and active to prevention messages and making proper use of the health system.
This study is an interesting step in unravelling the puzzle of cancer inequalities by migrant origin, taking into account SEP and using population-wide data. Such studies can contribute to identifying policy priorities as well as elaborate on the knowledge on disease aetiology. Future research is definitely needed to continue on this path of trying to identify the missing pieces. Considering the increasing ages of the labour migrant population in Belgium, the continuous monitoring of their health status and health needs is essential. In addition, it is important to investigate the risk factor patterns (i.e. smoking patterns) among migrant groups to see which groups need to be tackled in terms of primary prevention.