It's not diet, it's genetic/hormonal. I feed commercial layer feed just like most everyone does, plus they get extra supplements once or twice a week. And usually, they get to freerange a couple times a week. I've lost 3 SLWs, 1 GLW, 2 RIRs and almost lost Ivy three times and Ginger once. Currently, I have Olivia a non-hatchery crossbreed hen, suffering from the same thing, but every one other than Olivia has been a hatchery girl. My breeder types and ones hatched here, with the exception of Olivia, have never gotten this ailment.
I know I've said it before, but chicken hens are the only animal that gets spontaneous ovarian cancers like humans; in fact, to learn about ovarian cancer in women, they study hens. So, it seems almost inevitable for many of them, that they will die from some sort of ovarian/reproductive problem.