Doc Jones warns against using black salve in several lessons.  It’s very caustic and harms healthy skin along with the cancer.  If you make any wound poultice for your client’s healing issues omit the comfrey so it doesn’t encourage the cancer cell growth.  Simple plantain has amazing properties.
Check out Doc’s unit specifically on cancer (i.e.immunity support, blood klnz, nutritional support tinctures).  Is surgical removal possible?  Then your client can move ahead with diet and lifestyle changes like minimizing sugar, boosting omega 3s, green tea, broccoli sprouts, turkey tail mushrooms, etc.