This article kind of made a mess of the numbers. At one point it suggests the mortality rate increased, but that’s not what the actual research shows.
From OG article: “Our study showed that the global morbidity of early-onset cancer increased from 1990 to 2019, while mortality and DALYs slightly decreased”
The vast majority of the raw numbers increasing is because of the word population going from 5.3 billion to 7.75 billion in that same time. The next cause does seem to be diagnostic ability, especially when looking at what cancers saw the biggest increase.