<qa>  What is the number one predictor of incomplete treatment and difficulty with rehabilitation?Depression has many negative consequences for outcomes in those with cancer. It causes delayed treatments, increases in hospital lengths of stay, decreases in treatment adherence, poorer self-care, and decreased quality of life, even at 3 years post treatment. The presence of depression is the number one predictor of incomplete treatment and difficulty with rehabilitation. Therefore, investigators would also like to see if it is feasible to give patients ketamine during their routine cancer treatment treat depression and its negative effects on cancer treatment outcomes, and also help with anxiety, pain, and quality of life. The study will also use a placebo to compare to the good andor bad effects of ketamine. A placebo is not an active drug and it will be look the same as ketamine, as a liquid to be taken by mouth. 