Leukemia doesn't affect many enough people in reproductive age to cause a population explosion. Basically, no medical advance can cause population explosion in the rich world: there are very few people dying from disease in reproductive ages there. Making people who would otherwise die at 55 live through 95 does not make a population explosion because they won't have any kids anyways.
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Also what about the sudden population explosion? What if the survivors need after care for the rest of their lives, or expensive drugs?
Leukemia doesn't affect many enough people in reproductive age to cause a population explosion. Basically, no medical advance can cause population explosion in the rich world: there are very few people dying from disease in reproductive ages there. Making people who would otherwise die at 55 live through 95 does not make a population explosion because they won't have any kids anyways.
What sudden population explosion? I'm fairly sure that leukemia isn't playing a huge role in demographics.