This is the 12094th most frequent Korean word.
뇌종양의
"뇌종양의" means "of brain tumor" or "related to a brain tumor."
Here, '뇌종양의' is used as a possessive modifier for '발생 원인', specifying that the causes pertain to brain tumors.
뇌종양의 발생 원인은 아직 명확하지 않습니다.
The causes of brain tumors are still unclear.
In this sentence, '뇌종양의' modifies '치료', signifying that the treatment is specifically for a brain tumor.
뇌종양의 치료는 진행 중입니다.
The treatment for the brain tumor is underway.
Here, '뇌종양의' modifies '크기', indicating that the size being measured is that of a brain tumor.