<prompt> Which among the following malignancy is MOST SENSITIVE to radiotherapy?Serous cystadenomaDysgerminomaMucinous cystadenomaTeratoma  <response>: 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. 