I have found that oncology nursing is a very rewarding career. The pt., as you well know, are very appreciative of any little thing that you do for them. However, it is easily to get burned out on this end also.
You will enjoy your new career in nursing no matter if you go into solid tumor, malignant tumor, bone marrow transplant, hematology or whatever you wish - the field is wide open.
Congrats on your new career choice!