This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gynaecological Disorders in Obs., Subject name: Gynaecology & Obstetrics
Which among the following malignancy is MOST SENSITIVE to radiotherapy? 
Select and explain. 
A. Serous cystadenoma, B. Dysgerminoma, C. Mucinous cystadenoma, D. Teratoma
B: Dysgerminoma
Answer: B: Dysgerminoma 
Explanation: Ans. B. DysgerminomaNormally, dysgerminomas are unilateral. They are considered to be the most common kind of germ cellular tumor found in patients suffering with gonadal dysgenesis. They are highly radiosensitive and chemo-sensitive.Serous cystadenoma: The most common epithelial cell neoplasm. About 70% of these tumors are benign. The treatment of choice in such cases is surgery.Mucinous cystadenoma: Considered to be the second most common epithelial cell tumor of the ovary. Again, surgery being the treatment of choice.Cystic teratoma: Comprises about 60% of all benign ovarian neoplasms and 10-25% of all ovarian neoplasms. Surgical excision is the treatment of choice in such cases.