A prospective study of ovarian sex cord–stromal tumours in children and adolescents began enrolling participants in 2005.

Usually the lesion is surgically removed. Primarily, there is concern that the lesion identified in a patient could be cancerous, but there is also the risk of torsion, and possibly the development of symptoms. A stable lesion, however, could be clinically followed.

Variants with edema can be associated with Meigs' syndrome. They may be a part of nevoid basal cell carcinoma syndrome (Gorlin syndrome).

Treatment is variable, both due to its rarity and to its frequently slow-growing nature. Treatment ranges from watchful waiting to debulking and hyperthermic intraperitoneal chemotherapy (HIPEC, also called intraperitoneal hyperthermic chemotherapy, IPHC) with cytoreductive surgery.

A retrospective study of 83 women with sex cord–stromal tumours (73 with granulosa cell tumour and 10 with Sertoli-Leydig cell tumour), all diagnosed between 1975 and 2003, reported that survival was higher with age under 50, smaller tumour size, and absence of residual disease. The study found no effect of chemotherapy. A retrospective study of 67 children and adolescents reported some benefit of cisplatin-based chemotherapy.

Papillary serous cystadenocarcinomas are the most common form of malignant ovarian cancer making up 26 percent of ovarian tumours in women aged over 20 in the United States.

As with most ovarian tumours, due to the lack of early signs of disease these tumours can be large when discovered and have often metastasized, often by spreading along the peritoneum.

Transitional cell carcinoma of the ovary, abbreviated TCC of the ovary, is a rare type of ovarian cancer that has an appearance similar to urothelial carcinoma (also known as transitional cell carcinoma).

Prognosis and treatment is the same as for the most common type of ovarian cancer, which is epithelial ovarian cancer.

The median survival of primary peritoneal carcinomas is usually shorter by 2–6 months time when compared with serous ovarian cancer. Studies show median survival varies between 11.3–17.8 months. One study reported 19-40 month median survival (95% CI) with a 5-year survival of 26.5%.

Elevated albumin levels have been associated with a more favorable prognosis.

Ovarian cystadenoma is a cystic benign tumor of the ovary. Two types are recognized: serous and mucinous.

Women with benign germ cell tumors such as mature teratomas (dermoid cysts) are cured by ovarian cystectomy or oophorectomy. In general, all patients with malignant germ cell tumors will have the same staging surgery that is done for epithelial ovarian cancer. If the patient is in her reproductive years, an alternative is unilateral salpingoophorectomy, while the uterus, the ovary, and the fallopian tube on the opposite side can be left behind. This isn't an option when the cancer is in both ovaries. If the patient has finished having children, the surgery involves complete staging including salpingoophorectomy on both sides as well as hysterectomy.

Most patients with germ cell cancer will need to be treated with combination chemotherapy for at least 3 cycles. The chemotherapy regimen most commonly used in germ cell tumors is called PEB (or BEP), and consists of bleomycin, etoposide, a platinum-based antineoplastic (cisplatin).

Surface epithelial-stromal tumors are a class of ovarian neoplasms that may be benign or malignant. Neoplasms in this group are thought to be derived from the ovarian surface epithelium (modified peritoneum) or from endometrial or Fallopian tube (tubal) tissue. Tumors of this type are also called ovarian adenocarcinoma. This group of tumors accounts for 90% to 95% of all cases of ovarian cancer. Serum CA-125 is often elevated but is only 50% accurate so it is not a useful tumor marker to assess the progress of treatment.

10-year survival rates for mucinous tumors is excellent in the absence of invasion.

In the case of borderline tumors confined to the ovary and malignant tumors without invasion, the survival rates are 90% or greater. In invasive mucinous cystadenocarcinomas, the survival is approximately 30%

The standard of care for mucinous adenocarcinoma with clinical condition PMP involves cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), by surgical oncologists who specialize in treating PMP. Some surgeons also apply early post-operative intraperitonial chemotherapy (EPIC), adjunct to surgical cytoreduction and HIPEC. In situations where surgery is not required immediately, patients can be monitored via CT scans, tumor marker laboratory tests, and physical symptoms, to determine when, and if, surgery is warranted. Although some surgical procedures may be rather extensive, patients can and do recover from surgery, and the majority of these patients can and do live productive lives.

In debulking, the surgeon attempts to remove as much tumor as possible. CRS or cytoreductive surgery involves surgical removal of the peritoneum and any adjacent organs which appear to have tumor seeding. Since the mucus tends to pool at the bottom of the abdominal cavity, it is common to remove the ovaries, fallopian tubes, uterus, and parts of the large intestine. Depending upon the spread of the tumor, other organs might be removed, including but not limited to the gallbladder, spleen, and portions of the small intestine and/or stomach. For organs that cannot be removed safely (like the liver), the surgeon strips off the tumor from the surface.

Thecomas or theca cell tumors are benign ovarian neoplasms composed only of theca cells. Histogenetically they are classified as sex cord-stromal tumours.

They are typically estrogen-producing and they occur in older women (mean age 59; 84% after menopause). (They can, however, appear before menopause.)

60% of patients present with abnormal uterine bleeding, and 20% have endometrial carcinoma.

The 1997 International Germ Cell Consensus Classification is a tool for estimating the risk of relapse after treatment of malignant germ cell tumor.

A small study of ovarian tumors in girls reports a correlation between cystic and benign tumors and, conversely, solid and malignant tumors. Because the cystic extent of a tumor can be estimated by ultrasound, MRI, or CT scan before surgery, this permits selection of the most appropriate surgical plan to minimize risk of spillage of a malignant tumor.

Access to appropriate treatment has a large effect on outcome. A 1993 study of outcomes in Scotland found that for 454 men with non-seminomatous (non-germinomatous) germ cell tumors diagnosed between 1975 and 1989, 5-year survival increased over time and with earlier diagnosis. Adjusting for these and other factors, survival was 60% higher for men treated in a cancer unit that treated the majority of these men, even though the unit treated more men with the worst prognosis.

Choriocarcinoma of the testicles has the worst prognosis of all germ cell cancers

Fertility subsequent to treatment of surface epithelial-stromal tumors depends mainly on histology and initial

staging to separate it into early borderline (or more benign) versus advanced stages of borderline (or more malignant). Conservative management (without bilateral oophorectomy) of early stage borderline tumors have been estimated to result in chance of over 50% of spontaneous pregnancy with a low risk of lethal recurrence of the tumor (0.5%). On the other hand, in cases of conservative treatment in advanced stage borderline tumors, spontaneous pregnancy rates have been estimated to be 35% and the risk of lethal recurrence 2%.

Since Krukenberg tumors are secondary (metastatic), management might logically be driven by identifying and treating the primary cancer. The optimal treatment of Krukenberg tumors is unclear. The role of surgical resection has not been adequately addressed but if metastasis is limited to the ovaries, surgery may improve survival. The role of chemotherapy and/or radiotherapy is uncertain but may sometimes be beneficial.

There are several experimental therapies for endometrial cancer under research, including immunologic, hormonal, and chemotherapeutic treatments. Trastuzumab (Herceptin), an antibody against the Her2 protein, has been used in cancers known to be positive for the Her2/neu oncogene, but research is still underway. Immunologic therapies are also under investigation, particularly in uterine papillary serous carcinoma.

Cancers can be analyzed using genetic techniques (including DNA sequencing and immunohistochemistry) to determine if certain therapies specific to mutated genes can be used to treat it. PARP inhibitors are used to treat endometrial cancer with PTEN mutations, specifically, mutations that lower the expression of PTEN. The PARP inhibitor shown to be active against endometrial cancer is olaparib. Research is ongoing in this area as of the 2010s.

Research is ongoing on the use of metformin, a diabetes medication, in obese women with endometrial cancer before surgery. Early research has shown it to be effective in slowing the rate of cancer cell proliferation. Preliminary research has shown that preoperative metformin administration can reduce expression of tumor markers. Long-term use of metformin has not been shown to have a preventative effect against developing cancer, but may improve overall survival.

Temsirolimus, an mTOR inhibitor, is under investigation as a potential treatment. Research shows that mTOR inhibitors may be particularly effective for cancers with mutations in PTEN. Ridaforolimus (deforolimus) is also being researched as a treatment for people who have previously had chemotherapy. Preliminary research has been promising, and a stage II trial for ridaforolimus was completed by 2013. There has also been research on combined ridaforolimus/progestin treatments for recurrent endometrial cancer. Bevacizumab and tyrosine kinase inhibitors, which inhibit angiogenesis, are being researched as potential treatments for endometrial cancers with high levels of vascular endothelial growth factor. Ixabepilone is being researched as a possible chemotherapy for advanced or recurrent endometrial cancer. Treatments for rare high-grade undifferentiated endometrial sarcoma are being researched, as there is no established standard of care yet for this disease. Chemotherapies being researched include doxorubicin and ifosfamide.

There is also research in progress on more genes and biomarkers that may be linked to endometrial cancer. The protective effect of combined oral contraceptives and the IUD is being investigated. Preliminary research has shown that the levonorgestrel IUD placed for a year, combined with 6 monthly injections of gonadotropin-releasing hormone, can stop or reverse the progress of endometrial cancer in young women. An experimental drug that combines a hormone with doxorubicin is also under investigation for greater efficacy in cancers with hormone receptors. Hormone therapy that is effective in treating breast cancer, including use of aromatase inhibitors, is also being investigated for use in endometrial cancer. One such drug is anastrozole, which is currently being researched in hormone-positive recurrences after chemotherapy. Research into hormonal treatments for endometrial stromal sarcomas is ongoing as well. It includes trials of drugs like mifepristone, a progestin antagonist, and aminoglutethimide and letrozole, two aromatase inhibitors.

Research continues into the best imaging method for detecting and staging endometrial cancer. In surgery, research has shown that complete pelvic lymphadenectomy along with hysterectomy in stage 1 endometrial cancer does not improve survival and increases the risk of negative side effects, including lymphedema. Other research is exploring the potential of identifying the sentinel lymph nodes for biopsy by injecting the tumor with dye that shines under infrared light. Intensity modulated radiation therapy is currently under investigation, and already used in some centers, for application in endometrial cancer, to reduce side effects from traditional radiotherapy. Its risk of recurrence has not yet been quantified. Research on hyperbaric oxygen therapy to reduce side effects is also ongoing. The results of the PORTEC 3 trial assessing combining adjuvant radiotherapy with chemotherapy were awaited in late 2014.

Ovarian tumors, or ovarian neoplasms, are tumors arising from the ovary. They can be benign or malignant (ovarian cancer).

These tumours do better than other types of epithelial tumours of the ovary.

Smoking and the use of progestin are both protective against endometrial cancer. Smoking provides protection by altering the metabolism of estrogen and promoting weight loss and early menopause. This protective effect lasts long after smoking is stopped. Progestin is present in the combined oral contraceptive pill and the hormonal intrauterine device (IUD). Combined oral contraceptives reduce risk more the longer they are taken: by 56% after four years, 67% after eight years, and 72% after twelve years. This risk reduction continues for at least fifteen years after contraceptive use has been stopped. Obese women may need higher doses of progestin to be protected. Having had more than five infants (grand multiparity) is also a protective factor, and having at least one child reduces the risk by 35%. Breastfeeding for more than 18 months reduces risk by 23%. Increased physical activity reduces an individual's risk by 38–46%. There is preliminary evidence that consumption of soy is protective.

Benign fibromas may, but need not be, removed. Removal is usually a brief outpatient procedure.

Mucinous cystadenocarcinoma is a type of tumor in the cystadenocarcinoma grouping.

It can occur in the breast as well as in the ovary. Tumors are normally multilocular with various smooth, thin walled cysts. Within the cysts is found a haemorrhagic or cellular debris.

Papillary serous cystadenocarcinomas may exhibit psammoma bodies upon histopathology.

A cystic nephroma, also known as multilocular cystic nephroma, mixed epithelial stromal tumour (MEST) and renal epithelial stromal tumour (REST), is a type of rare benign kidney tumour.