Cancer is a rare pathology before the age of 40: a total of 14,000 new cases have been diagnosed in patients under age 40 in 2005, 1,700 under age 15 and 12,500 in the age-group of 15 to 39, this represents 4% of the cancers diagnosed in 2005. The number of deaths is small: in 2008, 2,235 patients died before age 40 in France, 246 under age 15 and 1,989 between age 15 and 39; this corresponds to 1% of the cancer deaths in 2008. The incidence increased between 1980 and 2005, both in the population aged 0 to 14 and in the population aged 15 to 39. Overall, cancer mortality has been decreasing for more than 25 years. The only increase in mortality is observed for brain tumours in children. The overall incidence increase is mostly due to the extension of screening coverage and to improvements in diagnostic procedures. The decrease observed for cervix cancer and lung cancer in men demonstrates the efficacy of screening and of tobacco smoking prevention. The mortality decrease is explained both by improved treatments and by the decreased incidence of some types of cancer. The increasing brain tumours mortality in children is worrying.