I've recently been working on doing OMDAD (one drinking session per day, giving time to absorb, then eating). Can't say I've gone past 18 hours yet but going dry is super powerful. Changes everything. You may have some good success in shrinking your tumor by shaking it up with dry fasting.

Make sure you alkalize first (lots of baking soda, possibly humic acid?) before you start, along with high doses of electrolytes (potassium, salt, maybe snake juice) and test your urine pH as you go for safety. Just like extended fasting, learning to drink only once per day seems to be great preparation for multiple days of going dry.

That is really about all you need to know. Doing super low intensity steady state cardio in a dry fasted state will melt away fat because your body will consume the fat cells to access water instead of nutrition. Re-hydrating is probably best with coconut water, cucumber, and/or watermelon.