Yes, unspayed female rabbits do have a much higher chance of developing cancer than a spayed rabbit if they are not bred. I don't really know the percentages off the top of my head lol but I know it is much higher regardless.
However, that doesn't mean it's wrong or cruel to not spay your doe if you aren't breeding her. Everyone has their own opinion and reasons to spay or not to spay and in some cases might not be able to afford it, so it's kinda up to you. It is highly suggested and recommended, and I agree with this, that if you have a pet female rabbit and are able to, get her spayed. It can prevent health problems and also all those hormonal problems you researched and shared here.
I'm more in the camp, though, to spay to lengthen their life and prevent potentially tragic health problems like cancer that could bring about costly vet bills and potential early death.
Not spaying doesn't mean your rabbit will get cancer and die at age 5 (look at cute Sophie on this thread!

) but it's just a preventative since the facts are there. As with any animal, you never know what will happen--going both directions, for spayed and not spayed. My Harlequin doe I had died of sudden stasis at 6yo, while my Lionhead has survived 2 ear infections and is going strong at 11yo. So you can't say what will claim your rabbit's life or what will happen to them.
Also, your rabbit is so adorable Juniper!
