Thank you for your answers.
I would like to say how sorry I am to posters here who have suffered sexual violence themselves 
Thank you for all your answers.
After reading peoples posts here, I was thinking that there is the extra difficulty that some core literature, which involves rape and sexual assault, is unlike Lolita in that it is not from (or close to) our own era. When it is from our time it is more likely the writer will be judging it to have been wrong which is some help, as the way in which it is shown to be wrong is part of the class discussion and part of the analysis. So a survivor of rape will feel supported to some extent.
The problem could be when the literature is from an era where rape was accepted as normal within the context of the time it was written.
The course in question might require the student to write about the subject analytically from the point of view of literary style and history alone, and therefore leave the student feeling there was no place for their instinctive reaction to the literature which might lack analytical attack as a result.
Another example I had not thought which venusinscorpio brought up was of a student studying rape law: the student needs to put all personal emotion aside to concentrate on points of law. Similarly, a student doctor who might be a rape survivor might need to study the physical effects of rape on a child/other needs to put emotion aside to note every physical detail.
In these cases the troubled student might even have to take an exam in the possibly personally distressing subject as part of their degree.
The standard of analysis expected is what is being examined and will not be change to accommodate an individual's experience. If the subject is absolutely core, it cannot be removed to solve the problem
I think it is a difficult question. I was prompted to think about it because of this article, which though I think it goes to far and is too unsympathetic, made me think about the difficulty.
newrepublic.com/article/121790/life-triggering-best-literature-should-be-too
It is unlikely lecturers receive any special training, and even if they did, they would be unlikely to be expert enough to know how to help a troubled student effectively.