In 1994, the first gene associated with breast cancer – BRCA1 (for BReast CAncer1) was identified on chromosome 17. A year later, a second gene associated with breast cancer – BRCA2 – was discovered on chromosome 13.
Since that time more types of cancer have been identified that may be caused by BRCA gene mutations, as have additional genes that fall under the HBOC Syndrome umbrella.
There are so many thing to know, and carriers continue to die or lose their loved ones at an alarming rate until we learn it. Because this is a fairly new science, we are just starting to receive solid information to guide HBOC carriers in their life-changing decisions.
A Word on Funding
Those with HBOC syndrome have been proven to have the highest rate of breast, ovarian and prostate cancer, yet larger cancer organizations do not always direct their funding for services and research proportionately, if at all. If you would like ensure your donations go directly towards research for the hereditary component of the type of cancer you are affected by or passionate about, ask those organizations to earmark your funds for that purpose, donate directly to a dedicated research institute or to the HBOC Society.
The Familial Breast Cancer Research Unit, led by Tier 1 Canada Research Chair Dr. Steven Narod, is a world leader in the study of inherited cancers.
With a particular focus on breast and ovarian cancers, Dr. Narod leads his team in the study of genetic mutations that are known to increase the risk of many cancers – most notably the BRCA1 and BRCA2 mutations. Through its extensive research, publications, data collection, genetic testing programs and collaborations, the team has become an internationally renowned leader in identifying and developing effective strategies to prevent and manage these cancers women and families with a high inherited risk.
Double mastectomy : Double mastectomy halves death risk for women with BRCA-related breast cancer. While existing research widely supports the benefit of a double mastectomy in preventing breast cancer in women with the gene mutation, the study’s researchers caution more research is necessary to confirm the benefit of a double mastectomy in reducing the risk of death in women diagnosed with BRCA-related breast cancer.
Pregnancy: Carriers of the BRCA1 and BRCA2 gene mutations who have children are significantly more likely to develop breast cancer by age 40 than carriers who have not had any children. Each pregnancy is associated with an increased cancer risk. An early first pregnancy does not mean protection for carriers of BRCA1 or BRCA2 mutations.
Breastfeeding: Women who have a BRCA1 mutation and breast-fed for a cumulative total of more than one year had a statistically significant reduced risk of breast cancer.2
Oral Contraceptives: Oral-contraceptive use may reduce the risk of ovarian cancer in women with mutations in the BRCA1 or BRCA2 gene.
Among BRCA1 mutation carriers, women who first used oral contraceptives before 1975, who used them before age 30, or who used them for five or more years may have an increased risk of early-onset breast cancer. Oral contraceptives do not appear to be associated with risk of breast cancer in BRCA2 carriers, but data for BRCA2 carriers is limited.
Fertility Drugs: The use of fertility medications does not adversely affect the risk of breast cancer among BRCA mutation carriers. However, the impact of fertility drug use among BRCA mutation carriers has not been studied closely due to the small number of carriers who have used fertility drugs. Any findings should be interpreted with caution. Further studies are required in this field.
Tubal Ligation: Tubal ligation is a suitable option to reduce the risk of ovarian cancer in women with BRCA1 mutations who have completed childbearing.
Oophorectomy: The high incidence of ovarian cancer suggests that oophorectomy (surgical removal of the ovaries) should be recommended in female BRCA1 and BRCA2 mutation carriers with a diagnosis of breast cancer, especially those with stage I disease. Breast cancer systemic therapy did not significantly alter the risk of ovarian cancer.
Oophorectomy is an effective means of reducing the risk of breast cancer in carriers of BRCA1 mutations. The data suggests oophorectomy is protective in BRCA2 carriers as well, but this needs to be confirmed in other studies.
Oophorectomy is associated with a reduced risk of ovarian and fallopian tube cancer in high-risk women, although there is a substantial residual risk for peritoneal cancer in BRCA1 and BRCA2 mutation carriers following prophylactic salpingo-oophorectomy (a type of preventive surgery performed by removing the fallopian tubes and ovaries).
Tamoxifen: Tamoxifen, a drug used in the treatment of breast cancer, has been shown to reduce the risk of contralateral (affecting both breasts) breast cancer in women with mutations in the BRCA1 or BRCA2 gene. The protective effect of tamoxifen seems independent of that of removal of the ovaries.
The protective effect of tamoxifen was not seen among women who had their ovaries removed but this subgroup was small. In contrast, a strong protective effect of tamoxifen was apparent among women who were premenopausal or who had undergone natural menopause.
The risk of contralateral breast cancer in women with a BRCA mutation is approximately 40 per cent at 10 years after the first breast cancer diagnosis, and is reduced in women who take tamoxifen or who undergo an ovary-removal surgery.
Screening and Preventive Practices: We found no association between ever having screening mammography and risk of breast cancer. Prospective studies are needed to confirm the results.
Other: Early chest X-rays may be a risk factor for breast cancer in BRCA1 carriers.
Prostate Cancer: Men with BRCA2 mutations have been found to be at increased risk of developing prostate cancer. It may be important to develop targeted chemotherapies to treat prostate cancer in men with a BRCA2 mutation.
Other Dedicated Research Organizations
A Word on Study Types
When people read about a research study, they may not pay attention to how the study was designed. But to understand the quality of the findings, it’s important to know a bit about study design.
According to the widely-accepted hierarchy of evidence, the most reliable evidence comes from systematic reviews, followed by evidence from randomized controlled clinical trials, cohort studies and then case control studies.
Research studies typically fall into one of two main categories:
Here researchers observe the effect of a risk factor, diagnostic test or treatment without trying to influence what happens. Such studies are usually “retrospective” — the data are based on events that have already happened. Most workplace health research falls into this category.
Cohort study: For research purposes, a cohort is any group of people who are linked in some way and followed over time. Researchers observe what happens to one group that’s been exposed to a particular variable — for example, the effect of company downsizing on the health of office workers. This group is then compared to a similar group that hasn’t been exposed to the variable.
Case control study: Here researchers use existing records to identify people with a certain health problem (“cases”) and a similar group without the problem (“controls”). Example: To learn whether a certain drug causes birth defects, one might collect data about children with defects (cases) and about those without defects (controls). The data are compared to see whether cases are more likely than controls to have mothers who took the drug during pregnancy.
Some strengths of observational studies
This may be the only way researchers can explore certain questions. For example, it would be unethical to design a randomized controlled trial (see below) deliberately exposing workers to a potentially harmful situation.
The results of observational studies are, by their nature, open to dispute. Example: A cohort study might find that people who meditated regularly were less prone to heart disease than those who didn’t. But the link may be explained by the fact that people who meditate also exercise more and follow healthier diets.
Here researchers introduce an intervention and study the effects. Experimental studies are usually randomized, meaning the subjects are grouped by chance. While not all controlled studies are randomized, all randomized trials are controlled.
Randomized Controlled Trial (RCT)
Eligible people are randomly assigned to two or more groups. One group receives the intervention (such as a new drug) while the control group receives nothing or an inactive placebo. The researchers then study what happens to people in each group. Any difference in outcomes can then be linked to the intervention.
Controlled Clinical Trial (CCT)
This is similar to an RCT, except that subjects are not randomly assigned to the treatment or control groups. This increases the chance for “bias”–that is, that people with similar qualities ended up in each of the groups which could influence the final results.
Some strengths of experimental studies
The RCT is still considered the “gold standard” for producing reliable evidence because little is left to chance.
There’s a growing realization that such research is not perfect, and that many questions simply can’t be studied using this approach. Such research is time-consuming and expensive — it may take years before results are available.
Source: At Work, Issue 42: Institute for Work & Health, Toronto
Research Search Engines
Use keywords to search for targeted research, e.g. hereditary breast, hereditary ovarian, hereditary prostate, BRCA or any of the other HBOC-related mutations.