what is risk of medicin break

My breastcancer started spreading. After finishing two of the available hormone blockers, I want to take a break from the oncological medicines - as long as I feel well - in order to spread the effectivess of the remaining medicines over a longer period. Meanwhile I do all possible efforts with diet and supplements (in short: vegan + broccoli sprouts and blueberries, and tofu) and daily long intense walks.

My question: what is the risk of not using the oncological medicines until/unless I start noticing that I need them - and stopping them after they took away the immediate problem?

FYI: Operated 11 years ago; diagnosed with metatstases 5 years ago - since then treated with Arimidex until it didn't work anymore (3 yr) and Tamoxifen which also doesn't work anymore (after 2 yrs). The last CT (May 2011) showed that the cancer is only active in the chest near the place where it all started, near the scar, "nibbling" from the chestbone. I feel excellent; no pains, no breathing problems.