noun
oncology
Medical term for the study and treatment of tumors, especially cancer.
彼は腫瘍学の専門医です。
He is a specialist in oncology.
腫瘍学の進歩により、多くのがんが治療可能になった。
Advances in oncology have made many cancers treatable.
癌 specifically means 'cancer'; 腫瘍学 covers both benign and malignant tumors.
Compound of 腫瘍 (tumor) + 学 (study, -ology).