Wow, you guys are some loving rat owners, what with the not-cheap concoctions and all. I can only give you my experience, and that is from years of keeping detailed litter notes when I had Zen Rattery, but you may find this worthwhile to read. From the original litter:
1. Agouti f - adopted to Bellaratta (florida breeder). Line discontinued, but lived past 3
2&3. Agouti males Adopted to Blue Velvet (died of Sendai or something in 6 months)
4&5 - died in care of another breeder
6. Black m- adopted to former best friend, a local breeder, and confiscated at 8 mo. Diagnosed renal failure @ 1.5. Died 2 y 11 mo.
7. Black m - adopted to my vet. He was the only rat in the litter to show myco signs. Died at 2 y 2 mo
8. Black f - adopted to breeder of the litter's mother. Confiscated at 8 mo. Died 2 y 8 mo CANCER
9. Agouti f - Spayed, no tumor. Died 3 y 1 mo.
10. Black m - died of a weird illness, neither cancer nor myco, @2y2mo In hindsight, could have been acute renal
SUMMARY: littermates in my care from birth (cooked food diet) lived from 2-3, no cancer
Of the 2 confiscated rats (took them back from bad homes), one fed lab blocks got cancer , the other fed horse food developed renal
Conclusion: feed home-made, water-rich diet, NO SUGAR (sugar feeds cancer). If they still get cancer, they were going to get it anyway. I tried the same stuff as Jorats (mycoplex, mushrooms), but it did nothing. Trying to remove the cancer killed the rat, as within 3 says of surgery, there were 10 new tumors at the site of the old one. I remember it was weird but my mom developed a tumor at the same spot, at the same time as the rat. Even *with chemotherapy, my moms tumor multiplied when exposed to oxygen. Why they don't learn to remove cancer in an O2-free room idk!!!