Breast and Ovarian Cancer Syndrome
Hereditary breast-ovarian cancer (HBOC) refers to cancer running in families with breast cancer and ovarian cancer. Typically an individual suffers from both cancers or several individuals within the pedigree suffer from breast and/or ovarian cancers. In such families we suspect a hereditary factor (gene mutation) to cause breast and ovarian cancer occurrences in that family.
The two most common genes that are known to cause HBOC are BRCA1 (located on chromosome 17) and BRCA2 (on chromosome 13).
- BRCA1 is a tumour suppressor gene that was first described in 1990. In its mutated form it causes breast cancer (up to 60% lifetime risk) and ovarian (up to 80% lifetime risk) cancer. Regularly BRCA1 becomes active from age 35 years onwards.
- BRCA2 mutations also cause breast (up to 60% lifetime risk) and ovarian (up to 50% lifetime risk) cancer. Regularly BRCA2 becomes active from age 40 years onwards.
Risk assessment includes a family tree (pedigree) but family history is false negative in approx half of the cases. It is especially misleading in small families, in families with a low number of females, in families with adoption or if non-paternity could be an issue.
Genetic testing is recommended if the female concerned carries a higher than 10% risk of carrying BRCA1 or BRCA2. Genetic testing involves a consultation with a clinical geneticist and a simple blood test. It is available in QLD through Genetic Health Queensland (publicly at no cost; however strict eligibility criteria apply) or privately (cost ~ $400).
The advantages of genetic testing include:
i. BRCA carriers may not only be at risk of ovarian or breast cancer but for both. Hence, a patient who was diagnosed with BRCA-related ovarian cancer previously is at very high risk of developing breast cancer subsequently and will benefit from enhanced breast screening or prophylactic surgery.
ii. BRCA carriers may pass the gene on to their sons and daughters who can be protected if tested positive.
iii. BRCA carriers respond well to PARP Inhibitors, which are a new class of cancer drugs. Hence, the outcomes of genetic testing may influence the selection of cancer medication.
Recent research from the Australian Ovarian Cancer Study confirms that ~15% of ovarian cancers are BRCA-related (inherited), which is larger than originally estimated. I recommend that all patients with high-grade, serous ovarian cancer should be tested for BRCA1 and BRCA2. The implications for the patient and her family are outlined above.
Age of onset: The risk of developing ovarian cancer in BRCA1/2 carriers (50% to 80%) is dramatically higher than in the general population (~1.3%). The ovarian cancer risk associated with BRCA1 or BRCA2 increases with age. Statistically, BRCA1 typically becomes aggressive from age 40 years of age onwards. Women diagnosed with BRCA2 need to take action from age 45 years. For young women I recommend to become proactive if they reach the age 5 years younger than the youngest relative diagnosed with BRCA-related cancer.
There are no "early" symptoms for ovarian cancer and three quarters of patients with ovarian cancer are diagnosed at stages 3 or 4. Across the board, survival for ovarian cancer remains poor throughout the past decades at approximately 40% to 45%.
What clinical management options are available to BRCA carriers?
Breast cancer screening (ultrasound, MRI), prophylactic surgery (mastectomy). In regards to the breast aspect of BRCA, I refer women to qualified breast surgeons.
- Screening (ovarian surveillance) is very unreliable because ultrasound and tumour markers frequently are unreliable. Both technologies often fail to detect small lesions. By contrast they are also falsely elevated and alarming in benign, harmless tumours.
- The Oral Contraceptive Pill (OCP) reduces ovarian cancer risk by 50%. However the remaining 25% to 40% ovarian cancer risk are still unacceptably high.
- Risk-reducing prophylactic surgery is >90% reliable and definitely recommended for postmenopausal women and those who have completed their family. Prophylactic surgery also reduces the risk of breast cancer. The earlier the ovaries are removed the higher is the protection against breast cancer.
There are several types of risk-reducing prophylactic surgery:
- Removal of both ovaries and fallopian tubes - this is the best researched option and reduces the risk of ovarian cancer to less than 5%. Women will become menopausal straight away and may require Oestrogen-Replacement Therapy. This option is the best option for women who had breast cancer previously, who are menopausal or who wish to maximally reduce the ovarian cancer risk.
- Removal of both fallopian tubes (ovaries remain) - this option emerged because some patients with BRCA who had their fallopian tubes and ovaries removed have been found with microscopic cancer within the fallopian tubes. This option is interesting for very young women who require some form of active management but who do not wish to become menopausal as yet. These women require IVF to fall pregnant. Little research is available on the effectiveness to prevent ovarian/fallopian tube cancer.
- When the ovaries are removed, the uterus can be preserved if a pregnancy is desired or removed laparoscopically if fertility is not required any longer. My default surgical approach for hysterectomy is key hole (see laparoscopic hysterectomy) which could be done at the same time.
Prophylactic surgery should be performed by an experienced laparoscopic surgeon or someone with a special interest in hereditary gynaecological cancer. Both ovaries and fallopian tubes need to be removed in their entirety through a retroperitoneal approach and specimens need to be properly labelled. Prophylactic surgery will induce instant menopause if performed on a premenopausal woman. Patients need to be medically fit to tolerate surgery, need to be aware of the most common risks and possible complications of surgery and require some investigations (blood tests, medical imaging) prior to surgery. A laparotomy is hardly ever required to perform this type of surgery. Hospital stay is 1 to 2 days.
Prophylactic surgery does not protect 100%. There is a 2% possibility of finding occult (microscopic) cancer at the time of surgery (most likely in one of the fallopian tubes). There is also a very small possibility of developing cancer of the inner lining of the abdomen and pelvis (peritoneum) subsequent to prophylactic surgery and removal of the ovaries. However, prophylactic, risk-reducing surgery is by far the most effective way to reduce that risk, whereas screening/surveillance is known to be ineffective.