Mucinous cystadenocarcinoma is a type of cancer that primarily affects the ovaries. It is characterized by the presence of mucin, a gel-like substance, within cysts that form in the tumor. This cancer can be aggressive and may spread to other parts of the body if not detected early. The exact cause of mucinous cystadenocarcinoma is not well understood, but it is more common in women in their reproductive years. Diagnosis typically involves imaging tests and a biopsy. Treatment often includes surgery, chemotherapy, and sometimes radiation therapy, depending on the stage of the disease.