If what you say were true - we "never cured cancer in small mammals" - then yes, the conclusion that cancer research is bullshit would have some merit.

But since we did cure a variety of cancers in small mammals, and since we are constantly (if slowly) improving both length of survival and cure rates in humans, the comparison does not stand.

(Also: the integration unit of human mind is not the synapse; it is an active zone, a molecular raft within a synapse. My personal view, as a molecular biophysicist turned neuroscientist, is that freezing damage is not fixable from basic principles (molecular drift over a few years is sufficient to prevent it completely). In my mind, the probability that some magical "damage repair" technique will be developed is within the same order of magnitude with probability that Rapture will occur. Cryonics is important primarily in the sense that it provides impetus for further research; but a radically different method of preservation is required before possibility of revivification reaches any reasonable level.)