I feel you @davixesk8. My father also has cancer. He has lung cancer with brain metastases, his cancer is stage 4. It is very difficult but never lose hope. Everything will be fine and your father will get better. Stay away from bad thoughts and stress.
Ask your doctor about the compatibility of cyberknife and gammaknife treatments. These radiation treatments are 100 times more effective than normal radiotherapy.
Also, don't forget to ask your doctor about immunotherapy and smart drug compatibility, these treatments are much stronger and less harmful than chemotherapy. God be with your father, your family and you.