Here is some more info to go with this post about leukemia in cats.
It's hard to find info about leukemia in cats because most results on Google are for Feline Leukemia Virus (FeLV) - which is a misnomer, it's a retro-virus, like HIV, not cancer itself, though it is suspected that it can cause cells to become cancerous.
Baby didn't have the virus. Baby had leukemia the cancer on its own. I got a little sad yesterday because I was telling someone and they scolded "Oh, well you should have vaccinated your cat!", implying I was neglectful and deserved it. I had to explain that it wasn't the same thing - but I'm not sure they believed me. It hurt because my husband and I treated Baby like she was our own baby. She couldn't have been more protected and pampered with care. Still I resisted my urge to slug this person. After all, if I thought someone failed to vaccinate a cat, wouldn't I "tsk tsk" too? I've been wondering if I should just tell people she died of "cancer" and leave it at that.
Info on standalone Leukemia in cats
There's two types of Leukemia, acute and chronic. Lots of subsets of each.
1) Chronic hits older animals, but is much slower, more treatable and the symptoms can be more subtle.
2) Acute usually strikes the young to middle aged and healthy. It kills very quickly. Based on Baby's health beforehand, symptoms such as very large, immature blasts, the extreme severity, and very sudden onset, I think she very clearly had Acute. The prognosis for this is "bad" as I highlighted below. Autopsy revealed it had already spread to her spleen.
A good plain-English article on Leukemia in cats and dogs
Therapy and prognosis for the different types of leukemia are quite different. ALL tends to have a very poor prognosis, and affected animals often succumb to secondary infection.... Unfortunately, pets with ALL often die within days to months of diagnosis.
A more medical article on Leukemia in cats with photos of blood cells
Although there are many similarities between the human and animal forms of the disease, the clinical course and outcome are very different. The prognosis with chemotherapy treatment is poor in canine and feline patients, and the average survival time is only a few months. Untreated, the estimated survival time from diagnosis is less than two weeks