What Is Complex Mass In Ovary Causing Stomach Pain?

my daughter is facing some kind of overy problem , there is complex mass meauring 16x10 cm , the doctors guessing that this is cencerous tumour , we are very worried about it , my daughter is just of 21 year old unmarried , we are very worried with the operation because of future after marriage problem , ca-125 marker has shown 140.4 , please guide what is can be? he has frequent severe pain in the stomach, it this possible that without operation we can come to know where or not this is due to cencer. further please tell that without operation is that problem be solved.