Which brand of medicine focuses on the study of tumors and cancers

You probably meant branch, instead of brand. But, the branch of medicine that studies cancer, tumors and their cures/causes, is called oncology.

Which means that, all the treatments we now have against cancer for example, chemotherapy, were, if not developed, used, studied and improved by oncologists.

Another example can be stem cell transplant, which is related to both cancer and tumors (which no, are not the same thing).

Hope it helped,

BioTeacher101

digestion

it excretes wastes

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.