It should be discussed and agreed to. Unilaterally assuming each will do it anyway is taking a chance. Making the mutual commitment increases the likelihood of success. Cancer is a complex disease with numerous treatment options. Often there is only one opportunity for success.
Effective treatment requires effort by both the patient and physician.
A clear understanding of what each can expect of the other will help. Thoughts and feelings of the doctor are transmitted neurologically, affecting the health of the patient. I will keep all my appointments on time, listen attentively and follow the agreed-upon treatment to the letter. I will keep you informed of any problems or questions. I will keep you informed of any therapy or medications I take.