Answer: Burkitt lymphoma.
Step-by-step explanation:
Burkitt Lymphoma is a form of non-Hodkin's lymphoma in which cancer starts growing in the B-cells of the immune system.
This tumor is known as the fastest growing tumor inside the human body. It is also associated with the impaired immunity and is very fatal if left untreated.
Chemotherapy is helpful in this case as it can increase the life time of the people suffering from Burkitt lymphoma.