Suggest Treatment For Ovary Enlargement

my daughter who got married 2 years back not pregnant by control, staying with her husband .She had a problem with every 15 day periods for the last six months and having medicines.Last 15th day period was not found and went again and was checked by her doctor for enlargement in her ovary 15 centimeters and advised for surgery.she is 27 year old .what do you advise please .