In France, in 2018, the estimated number of new cases of mature T/NK-cell lymphoma was 1,777, including 997 in men and 780 in women. Key points: A cancer with an intermediate prognosis, with a 1-year standardized net survival rate of 78% and a 5-year rate of 62% for individuals diagnosed between 2010 and 2015; Better 1-year net survival in women compared to men before age 60 at diagnosis (at age 30, +6 percentage points), then the opposite trend beyond age 80 (-9 percentage points); Decrease in 5-year net survival based on age at diagnosis: 88% at age 30 and 49% at age 80; A trend toward improvement (not statistically significant) in net survival between 2005 and 2015 regardless of age at diagnosis.