This is the first French study of this scope. Public health France, in collaboration with several institutes, including the National Cancer Institute and the Cancer League, published the results of a major study Led on the incidence of cancers in 15-39 year olds between 2000 and 2020. The observation of this age class of “adolescents and young adults”, never studied in France as a whole and over such a long period, reveals certain successes and failures of the prevention strategy against these diseases.
For this study, Public Health France and its partners collected data from 19 French departments, representing almost 25 % of the French population, for a total number of 54,735 adolescents and young adults who have had a cancer diagnosis over these twenty years. And the results are far from harmless: thus, “if cancers in adolescents and young adults remain rare with a much lower incidence than among those over 60”, their increase remains marked. Between 2000 and 2014, the incidence of all cancers increased by 1.62 % per year, before dropping by 0.79 % per year between 2015 and 2020.
Six cancer increasing
Above all, the incidence of six cancers increased during the period 2000-2020: glioblastomas – an aggressive and frequent form of brain cancer – (+6.11 % on average per year), kidney cancers (+4.51 % per year), liposarcoma – tumors in adipose tissues – (+3.68 % per year), Hodgkin lymphomas (+1.86 % per year), breast cancers (+1.6 % per year), as well as colorectal cancers (+1.43 % per year). “These results call for new studies to better identify the underlying risk factors responsible for these trends in order to promote or strengthen prevention in adolescents and young adults,” explain the authors of the study.
First causes are however put forward by the authors to try to explain the increase in some of these cancers. “Obesity could be an explanatory factor in the increase in cancers of the digestive system (including colorectal) as well as kidney cancers,” said the study, even if it specifies that “this remains to be demonstrated”. In addition, “the results concerning tumors of the central nervous system must be interpreted with caution: changes in the classification of these tumors occurred during this period”, explains the study, which also affirms that technical improvement in cancer detection can also have an impact on this increase.
The importance of prevention
For some other cancers, on the other hand, the incidence is down in 15-39 year olds. Starting with melanomas – a particularly dangerous form of skin cancer -, decreased by 3.05 % per year, “probably in connection with the prevention measures” implemented by the public authorities. Head and neck cancers are also down (-1.24 % on average per year), even if the incidence of the latter represents a “heterogeneous set limiting the interpretation of the results”.
The number of certain cancers, finally, remained relatively stable, especially during the decade 2010. This is the case of testicular cancers, after an increase until 2012, but also cancers of the cervix, which had dropped until 2013. About the latter, the study authors claim that their incidence could decrease “if the vaccinal coverage against the papillomavirus (HPV) Recommending to “continue the efforts made with the aim of reaching a vaccination coverage of 80 % in adolescents by 2030”.
In general, the study claims that “efforts are necessary to identify the risk factors responsible for these trends in order to promote or strengthen prevention strategies in adolescents and young adults”. But the authors also assure that it is “encouraging on the one hand to note a stabilization of the incidence of certain cancers in recent years, and on the other hand an incidence of other cancers such as melanomas”.