Causes and Risk Factors of Ovarian Cancer
Although the exact cause of ovarian cancer is unknown, various risk factors have been identified which may be linked with its development. It is important to understand that while these risk factors increases the chance of ovarian cancer to various degrees, it is not a definitive cause that will result in a malignancy in every person. Some of these risk factors may include :
Repeated ovulation provides opportunities for cell mutation following repeated disruption of the epithelium (by rupture of the Graafian follicles as it releases an ovum) as well as activation of cellular repair mechanism during and after ovulation. This theory is substantiated by observations that the following conditions protect against ovarian cancer.
- Chronic anovulation (absence of ovulation).
- Long term use of oral contraceptives.
- Multiple childbirths.
However, ovulation is a normal part of the menstrual cycle and should not be interrupted as a means of protecting against ovarian cancer.
The role of genetic factors in ovarian cancer is undisputed. Many observations support this fact, such as :
- Mutations in BRCA1 and BRCA2 genes have been associated with risk of ovarian cancer.
- It has been observed that women diagnosed with breast, uterus, and colon cancer are at increased risk of developing ovarian cancer.
- Various genetic disorders, such as Turner’s syndrome and Klinefelter’s syndrome have been associated with certain types of ovarian cancer.
- A close family history (mother, daughter, or sister) affected with ovarian cancer may be found.
- Epithelial ovarian cancers are more common in postmenopausal women. Read more on types of ovarian cancers.
- Germ cell carcinomas seem to occur more commonly in younger women or teenage girls.
- Causcasian women seem to be more at risk than African American women.
- Ashkenazi Jewish women are more likely to have mutations in the BRCA1 and BRCA2 genes, which are considered as important risk factors for ovarian cancer.
- Norwegian, Dutch, and Icelandic people also have higher frequencies of BRCA1 and BRCA2 mutations.
It has been suggested that long term use of clomiphene citrate, a fertility drug, may increase the risk of ovarian cancer. This drug promotes ovulation and may therefore be a factor as discussed under repeated ovulation above.
A nulliparous woman is a woman who has never had children. This appears to be a risk factor for developing ovarian cancer. Conversely, multiple childbirths seems to offer protection against ovarian cancer.
Increased fat consumption has been associated with development of ovarian cancer. For this reason, obesity may be considered as a risk factor.
Exposure to Talc
The presence of talc granulomas in ovaries of patients who have not been operated upon previously has led to the hypothesis that women who place talcum powder on their external genitalia run the risk of developing ovarian cancer. This theory is yet to be substantiated, although the fact remains that talcum powder, as a foreign body, can be considered carcinogenic – a substance that is capable of causing cancer.
Hysterectomy (removal of uterus) or tubal ligation (surgery for permanent closure or tying of the fallopian tubes) may decrease the risk, possibly by preventing foreign bodies from entering through the vagina and reaching the ovaries.
Hormone Replacement Therapy (HRT)
Women on long term HRT using estrogen alone (without progesterone) may be at risk.
Radiation to the pelvic area may be a risk factor. This may be seen with treatment of malignancies in the lower abdomen and pelvis.
Endometriosis may be a very rare risk factor for ovarian cancer.