Sunday August 31, 2008
Can genetic testing be useful?
By Dr TEO SOO HWANG
This is the second in a series of four articles by the Cancer Research Initiatives Foundation (CARIF) that explores how genes are linked to diseases, the relationship between genes and cancer, and what is genetic testing and counselling. This week, we explore whether genetic testing adds anything to our ability to prevent disease.
MRS Wong is a 43-year-old woman who has been diagnosed and treated for breast cancer. Her younger sister, Lynette, is 41 and has three children, all in their teens. Mrs Wong and Lynette’s mother died of breast cancer at the age of 48.
Mrs Wong’s doctor has offered her an option to use a genetic test to determine whether her breast cancer is due to a gene that she inherited from her mother or her father.
Mrs. Wong is tempted to take the test – she thinks that if she could find out once and for all why she developed breast cancer, she could plan for her future and her children’s future.
On the other hand, she wonders whether it is better not to know. At least, she could have some hope that her cancer occurred by chance and that her children may not have to go through what she did.
The test results show that Mrs Wong has a change in a gene called BRCA1 (pronounced Bra-Kah One), which accounts for between 5% and 10% of breast cancer cases diagnosed in Malaysia each year. This gene triggers breast cancer in both men and women, and up to 80% of women with this gene develop cancer.
Mrs Wong knows that her children have a 50% chance of having the same altered gene and she wants them to be tested because she knows that early detection is very important for survival.
Mrs Wong knows that because of the altered gene, she is also at risk of developing ovarian cancer. As she has already decided that she does not want any more children, she chooses to remove her ovaries surgically because surgery would reduce her risk of both breast and ovarian cancer. She wants “peace of mind” – to know that she has done everything possible to prevent cancer from happening.
Her sister, Lynette, is different from Mrs Wong and she does not want to be tested. As a teenager, it was hard for her to watch her mother suffer from cancer and she thinks it is better not to know. She does not tell her children about the genetic test because she is afraid that they will face prejudice even before they have a chance to have a full life – what if there is discrimination at work, affecting their job prospects? Discrimination when they apply for medical insurance? Perhaps even discrimination by prospective spouses?
But Lynette is also worried. What if she does have the altered gene and without regular check-ups, she develops cancer and is only treated at a late stage when chances of survival are poorer? She is devastated by the uncertainty and becomes depressed and anxious.
A real dilemma
This hypothetical story illustrates some of the ethical, legal and social issues that are raised by the availability of genetic testing for diseases.
In the past few decades, researchers have learned how to test for hundreds of genetic disorders and the research is progressing at such a fast pace that new tests are coming out all the time. The tests can be very effective in diagnosing diseases and they can also be very useful in predicting the chances that a person will develop a particular disease later in life.
For some diseases, such as breast cancer and ovarian cancer, there are options available for those who have inherited an altered gene. Researchers know that by choosing to remove her ovaries or her breasts, Mrs Wong will significantly reduce her chances of developing either of those cancers.
Researchers know that MRI scans and mammograms would be more effective at detecting early cancers in women such as Mrs Wong and Lynette, and they could go for regular checkups to detect cancer at an early stage, where it can be treated more effectively and with greater success.
In other words, the only real use of the genetic test is to tell Mrs Wong and Lynette and their family how each of them stands – one way or another. Such information could change their lives, in ways that they may not expect.
For example, if Lynette found that she did not have the altered gene, she might be relieved, but it is also possible that she may feel guilty because Mrs Wong, her sister and closest friend, was not spared.
You might think that Lynette would be sad to find out that she has the altered gene and is very likely to get breast cancer. But Lynette may discover that it is a big relief to know what she has always feared. She might stop living in denial and finally sign up for more regular checkups.
Finally, Lynette and Mrs Wong must decide how to handle information in a way which is fair to herself, her family and to others. Should they break the news to their family? Who else should know? When should she tell her boss – now, or when they fall ill? Does she have to tell her insurers? If she tells the insurance company before she applies for insurance, will she be eligible? Does she have to inform the insurance company if she already has insurance?
Ongoing research
Perhaps Lynette and Mrs Wong’s decision regarding genetic testing would be affected by developments in research. Researchers now know a lot more about what the BRCA1 and BRCA2 genes do, and are using this information to develop ways of preventing the cancer and working on a cure. Treatment may come in time to help Lynette and Mrs. Wong, or perhaps in time to help their children.
What would you do?
Please note that all women have a risk of developing breast cancer, even if no one else in the family has cancer. Thankfully, breast cancer can be treated effectively if detected early and therefore, every woman should be “breast aware” and women over the age of 40 should have regular mammograms.
- The third article in this series will explore whether genetic testing of SNPs through “direct-to-consumer” testing can help determine the likelihood of developing a particular disease and add anything to our ability to prevent disease.
Dr Teo Soo Hwang is the Chief Executive of Cancer Research Initiatives Foundation (CARIF). CARIF is a Malaysian independent cancer research organisation whose mission is to conduct fundamental and pioneering research on cancers prevalent in Malaysia, with potentially far-reaching implications for prevention, diagnosis, treatment and therapy (www.carif.com.my). Together with University Malaya, CARIF has recently published a study showing that some Malaysians also inherit the BRCA1 and BRCA2 genes which puts these women at risk to breast and ovarian cancer.
For further information, e-mail starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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