their cancer diagnosis from them. In Spin by Robert Charles Wilson, Earth humans have roughly the same level of medical science as us (a treatment for Multiple sclerosis is mentioned but is not 100% effective). However, the Mars humans (who have had millions of years over their Earth cousins) have developed a way to transform into what they call the Fourth Life Stage (after childhood, adolescence, and adulthood), allowing them to live for many more decades. In order to avoid a population boom, those who choose to undergo the procedure are forbidden from reproducing. The novel itself starts with the protagonist (an Earth human) undergoing the same procedure while having flashbacks to when it all started as a side-effect of the process. Mikhail Akhmanov and Christopher Gilmore's Captain French, or the Quest for Paradise has humans on most settled planets have cures for all ills, including aging . Cell Regeneration (or CR for short) is a one-time treatment that stops the aging process in its tracks. It's completely reversible, although the reverse is only done as punishment for heinous crimes (in lieu of the death penalty). The protagonist was actually born on Earth before CR was developed but spent much of his life performing relativistic jumps. He got the treatment much later than most (early 50s), and his graying hair causes looks of puzzlement to most. Even a planet full of religious fanatics not only doesn't ban CR but provides it for free as God's blessing. It's also the only