New insights regarding pharmacologic approaches for ovarian cancer prevention

New insights on the pathogenesis of ovarian carcinoma: molecular basis and clinical implications

Ovarian carcinoma can be subdivided into two categories termed type I and type II. Type I tumours, usually having an indolent clinical behaviour, are often detected in early stage, and rarely harbour p53 gene mutations. Each histological type has a distinct molecular profile with mutations of genes involved in different signalling transduction pathways, such as KRAS, BRAF, CTNNB1, PTEN, PIK3CA and ARID1A. Type II tumours, accounting for 75% of the cases, have a very aggressive biological behaviour, are usually in advanced stage at presentation, harbour p53 gene mutations in 80% of the cases, and sometimes have alterations of homologous recombination (HR). Both type I and type II tumours arise from extra-ovarian precursors. Serous carcinomas derive from tubal epithelium, endometrioid and clear cell carcinomas from endometrial tissue, and mucinous and Brenner tumours from transitional epithelial cells located near the tubo-peritoneal junction. These new concepts on the pathogenesis of ovarian carcinoma could deeply modify both the preventive approach in women with germ-line BRCA₁ or BRCA₂ mutations and the treatment of patients with advanced or recurrent disease. For instance, BRAF inhibitors could be used in low-grade serous carcinomas, PIK3CA inhibitors could be employed in clear cell carcinoma, and poly (ADP-ribose) polymerase inhibitors could be used not only in hereditary ovarian carcinoma but also in non-hereditary, high-grade serous ovarian carcinoma which sometimes shows defective HR.

GnRH agonist therapy in a patient with recurrent ovarian granulosa cell tumors

A 65-yr-old woman presented 17 yr status post-hysterectomy with bilateral ovarian salpingo-oophorectomy, attributable to ovarian cancer. She was admitted to our hospital, with multiple cystic liver masses and multiple large seeded masses in her abdomen and pelvic cavity. Histological examination of the pelvic masses demonstrated granulosa cell tumors. After two courses of systemic combination chemotherapy, with paclitaxel and carboplatin, the masses in the abdomen and pelvic cavity increased, and debulking surgery also failed because of peritoneal dissemination with severe adhesion. Finally, she underwent palliative radiotherapy for only the pelvic masses obstructing the urinary and GI tracts, and monthly hormonal therapy with a gonadotrophin-releasing hormone agonist; leuprorelin 3.75 mg IM. Subsequently, multiple masses beyond the range of the radiation as well as those within the radiotherapy field partially decreased. This partial response had been maintained for more than 8 months as of the last follow-up visit. Owing to its long and indolent course and the low metabolic rate of the tumors, advanced or recurrent granulosa cell tumor (GCT) requires treatment options beyond chemotherapy, surgery, and radiotherapy. Hormonal agents may provide another treatment option for advanced or recurrent GCT in those who are not candidates for surgery, chemotherapy, or radiotherapy.

Does hormone replacement therapy prevent epithelial ovarian cancer?

Two much-debated hypotheses regarding the aetiology of epithelial ovarian cancer (EOC) are incessant ovulation and gonadotrophin stimulation. A significant inverse correlation is found between the risk of EOC and number of pregnancies, duration of oral contraceptive use (about 10% risk reduction per year) and duration of breastfeeding. Whereas ovulation in the 20-29 year age group was associated with a 20% increase in risk for each year of ovulation, maximum protective effect was noticed in late childbirth (>35 years). Although both in-vitro and in-vivo studies showed that gonadotrophins may initiate and stimulate the growth of EOC, it is not known whether gonadotrophins promote EOC. FSH and LH receptors have been detected by ligand-binding assay and by reverse transcriptase polymerase chain reaction in ovarian surface epithelium (OSE) and in malignant epithelial ovarian tissue. Key aetiological events for this cancer may occur in the premenopausal period. Although hormone replacement therapy (HRT) can lower FSH and LH concentrations substantially, it cannot reduce EOC. The ideal time of ovulation and/or gonadotrophin suppression for prevention of EOC, and why oral contraceptives (OC) can but HRT cannot reduce EOC effectively, are unknown. Various growth-related genes, factors, adhesion molecules and angiogenic factors are present in OSE. Pituitary ovarian axis hormones seem to maintain a delicate balance towards growth control whilst the resultant chain of abnormal growth-promoting events occur at cellular level. Reports regarding the relation of exogenous and endogenous hormones, especially oestrogen, and post-menopausal EOC are reviewed.

Carcinogenic potential of ovulatory genotoxicity

Ovulation is a rate-limiting event for the perpetuation of a species; unfortunately, it imparts a cancer risk. Reactive oxidants generated during the mechanics of ovulatory follicular rupture damage the DNA of ovarian surface epithelial cells that are located within a limited diffusion radius. Those cells that survive the trauma of ovulation, along the margins of a ruptured follicle, proliferate and migrate to reconcile the discontinuity within the ovarian epithelium created at the site of oocyte release. It is conceivable that clonal expansion of an ovarian surface epithelial cell with unrepaired DNA, but not committed to death, could be an initiating factor in the etiology of common ovarian cancer. In fact, the majority of cancers of the ovary are derived from the surface epithelium; and circumstances that avert ovulation (oral contraceptive use, pregnancy/lactation) protect against ovarian adenocarcinoma. Not surprisingly, the genotoxic potential of ovulation is exacerbated by malfunctions in tumor suppressor/cell-cycle arrest and base-excision repair mechanisms. Recent experimental evidence indicates that vitamin E and progesterone protect against ovarian metaplasia by negating the oxidative stress of ovulation and by enhancing the repair capacity (genomic integrity) of the surface epithelium, respectively. Ovarian cancer of surface epithelial origin is a deadly insidious disease because it characteristically remains asymptomatic until it has metastasized throughout the abdominal cavity; therefore, prevention is a high priority.

Hormonal treatment of a recurrent granulosa cell tumor of the ovary: case report and review of the literature

BACKGROUND

Granulosa cell tumors of the ovary are rare, primarily treated surgically. In advanced or recurrent disease, data are inconclusive regarding the benefit of either primary or adjuvant chemotherapy. Hormonal therapy has been suggested as an alternative treatment.

CASE

Our patient had three recurrences of estrogen receptor negative and progesterone receptor positive GCT, the first two treated by surgery with or without adjuvant chemotherapy. For the third recurrence, the patient received alternating biweekly cycles of megestrol and tamoxifen. Computed tomography showed stable disease at 6 months, partial response at 18 months, and complete response at 22 months. The patient continues on hormonal therapy and has been disease-free for 5 years.

CONCLUSION

This study and others suggest that hormonal therapy may provide another option for treating these relatively rare tumors.