In terms of hepatotoxicity: In the studies I have read, it's true that the hepatoxic effects of tamoxifen have shown to increase incidents of fatty liver, but only after 12 weeks of continuous administration at the very earliest in otherwise unhealthy patients (breast cancer patients). All hepatocellular carcinomas correlated with tamoxifen use have been seen in patients using such drugs, always in combination with other drugs/therapies, for years.
I have never seen a study on healthy individuals (other than rats), a study that used short periods of time that found true hepatic distress, or a study that was other than correlational in this regard.
It is also worth noting that comiphene DOES NOT have the same level of hepatotoxicity, nor has been shown to be carcinogenic to the liver (nor other tissue, with a POSSIBLE exception of the uterus).
In regards to other cancer (uterine example): AAS users are largely male. While at least one MD has speculated that the prostate may be similarly effected by SERMS as the uterus has been suggested to be, no evidence yet presented supports this speculation.
With the problems present in these studies (not accounting for possible drug interactions, possible immune affectation due to the patients condition, extended duration, correlational nature, lack of controls), we can ONLY say that these studies do not have enough apparent external validity to draw conclusions in regard to AAS users use of SERMS for PCT.
In other words, we can only say that if you are a woman who is ill with breast cancer, and who is using multiple drugs and therapies for long periods of time, SERMS MAY elevate the risk of certain cancers.
In light of other possible issues of SERM use, such as ocular toxicity, up-regulation of progesterone receptors, and these issues already discussed, it's best to play it safe, but not using these drugs for PCT has its own adverse health effects that one might have to deal with immediately.