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The Legacy of DNA

Author: Karen Hart
May, 2014 Issue

Should you undergo genetic testing? It depends.

 
 
 
"Marilyn" was 17 years old when her mother died of breast cancer, an experience that left a lasting impression on her. But rather than brooding about the possibility of having to face the disease herself someday, Marilyn focused on living her life. She married, had three sons and began working in the wine industry. At the same time, she was proactive and had mammograms every year starting at age 29. When she was 36 years old, a year shy of the age her mother died, she discovered a lump under her arm the size of a goose egg.
 
Her doctor believed it was an infected lymph node, but after the lump was surgically removed and sent to a pathology lab, it was diagnosed as melanoma (a type of skin cancer). At the time, an oncologist told her there was a 60 percent chance the melanoma would return, but advised her to live her life and not dwell on it. Since Marilyn had three small sons at home, she took his guidance to heart, but she also scheduled regular checkups.A couple years later, another melanoma appeared above her knee. She had that one removed, too.
 
Nine years later, at age 44, Marilyn was diagnosed with breast cancer. She had a mastectomy, followed by chemotherapy. In 2006, her gynecologist suggested she consider genetic testing at UC San Francisco (UCSF), but Marilyn decided against it. “I wasn’t interested,” she says. “I’d been cancer-free for 12 years and didn’t think it would ever come back, so I didn’t want to know if I had a predisposition.”
 
There was another incidence of melanoma on her leg, and then breast cancer struck again in 2008. “It was a triple negative tumor and this time the cancer was more aggressive,” she says. Marilyn had another mastectomy, followed by chemotherapy treatments.
 
When her surgeon recommended genetic testing, she finally agreed. “I knew I probably had the gene mutation,” says Marilyn. “My mother, great aunt and great grandmother all had breast cancer. I would’ve been surprised if the gene test came back negative, but I wanted my children and grandchildren to have the information so they could be proactive in their health care and make decisions that could save their lives.”
 
Marilyn was tested for BRCA gene mutations in 2009, which identified a mutation in her BRCA2 gene, putting her at an increased risk of breast, ovarian and peritoneal cancer. She also learned the mutation causes an increased risk of melanoma. She met with Kathleen Mott, an advanced practice nurse in genetics (APNG) with Redwood Regional Medical Group in Santa Rosa, who explained the mutation, the possible risks and her options. “She explained everything, then asked what I wanted to do,” says Marilyn. Given her personal history, the test results and her family history, Marilyn took charge. “I hated the thought of having another surgery, but since the BRCA2 gene can also cause ovarian and fallopian tube cancer, I wanted to be proactive. I didn’t care how many scars I had. I wanted to be alive.”
 
Although uterine cancer isn’t increased with BRCA gene mutations, Marilyn opted to have a complete hysterectomy with da Vinci robotic surgery (a less invasive procedure) at UCSF. “The surgery took four hours, I woke up and was walking a few hours later. They sent me home the next morning.”
 

The history of genetic testing

The field of genetic testing has been in existence for half a century, and today there are four major categories. Prenatal genetic testing, the oldest and most common type, can identify conditions such as Down’s syndrome and heart defects. Cardiovascular and neurological testing are newer, growing fields. Genetic testing for a predisposition (heightened risk) of cancer is now the standard of care in oncology, and cancer genetic counseling and testing is available in the North Bay.
 
“There have been a lot of advancements in the field of cancer genetics, especially in the last 20 years,” says Lauren Bowling, MS, LCGG, a licensed genetic counselor with California Pacific Medical Center in San Francisco.
 
“It wasn’t long ago that North Bay residents at risk of hereditary cancer were referred to Stanford or UCSF for genetic counseling and testing,” adds Mott. “It’s important to offer these services locally so those in need can be seen expeditiously.”
 

The BRCA genes

Breast cancer is the second most common cancer among American women (behind skin cancer), meaning about one in eight women in the United States will develop invasive breast cancer during her lifetime, according to the American Cancer Society (ACS). The two genes that are most commonly tested for mutations in relation to breast and ovarian cancer are BRCA1 and BRCA2. “The BRCA genes are tumor suppressors, but when they’re mutated, they don’t work,” explains Paula Kelleher, a nurse practitioner at the Breast Care Center at Kaiser Permanente in Santa Rosa.
 
Both men and women have BRCA genes, and inheriting a mutation in either gene causes an increased risk for cancer. Although BRCA mutations are usually associated with women, men have the same chance of inheriting a BRCA mutation. And anyone with a BRCA mutation can pass it on to their children and is also at risk of developing certain cancers. In addition to melanoma, ovarian and breast cancers (including male breast cancer), other cancers associated with BRCA mutations include pancreatic and prostate. And though male breast cancer is rare, when it occurs, 15 percent of men with the disease will have a BRCA gene mutation; testing is always suggested in men with breast cancer.
 
Though many people have a family history of breast cancer, the majority of breast cancer is not due to inherited mutations, says Mott: “A general misconception is that people believe all cancer is inherited.” And when high-profile celebrities such as Angelina Jolie and Christina Applegate test positive for BRCA mutations and make headlines because they choose to have preventive mastectomies, she says, it creates a heightened awareness in many women who may not have an inherited risk to get tested. But according to Mott, 90 to 95 percent of women with breast cancer do not have inherited breast cancer. “BRCA mutations pose the greatest risk to developing breast and ovarian cancer, but fortunately, they’re rare,” she insists.
 
And even if you test positive for a cancer mutation, it doesn’t necessarily mean you’re destined to get cancer, adds Kelleher. “A mutation doesn’t cause cancer, it just makes the person vulnerable to developing cancer,” she says. “It’s a susceptibility syndrome.”
 
Although having a BRCA gene mutation increases cancer risks, mutations don’t operate in a vacuum. A mutation carrier’s chance of developing cancer is also affected by factors such as lifestyle choices, environmental exposures and reproductive history. “We know the development of cancer is more complicated than DNA alone,” Mott states. “Evidence of this fact is provided by studies of identical twins that don’t develop the same cancers.”
 

The importance of counseling

According to Mott, there are several questions you should consider before pursuing genetic testing. First, is the test appropriate (does your family or personal history indicate a possible predisposition)? Second, do you want to know whether you have a mutation? And finally, would you use the information to make different health care decisions? Understanding the implications of the results can be life altering, which is why it’s important to work with a cancer genetics specialist. Sometimes the results are straightforward, but at times, they’re not. It’s not like testing for blood sugar or cholesterol. “The results obtained from genetic testing can be inconclusive, something people should know before undergoing the tests,” says Mott.
 
“The BRCA test is not always a yes/no test,” adds Kelleher. “It requires a genetics counselor to also look at the personal and family history to assess if the person is at high risk and then to interpret the test results in this context. With genetic counseling, the person also has support once the information is known.”
 
There are three possible results with genetic testing. A positive result means the laboratory has identified a mutation that increases the patient’s risk of developing certain cancers. A negative result means a mutation was not identified; however, this result doesn’t change your personal and family history (recommendations will be made based on personal and family history). A patient who receives an inconclusive result is advised to remain in contact with a counselor, since it may be reclassified over time as data is accumulated.
 
When a test identifies a BRCA mutation, women (and men) have options. For example, cancer screenings can be intensified with breast exams, mammograms and breast MRIs beginning as early as age 25; patients can opt to use a risk-reducing medication such as Tamoxifen, a drug that reduces your risk by 50 percent; or a patient can choose to undergo preventive surgery to reduce the risk of breast or ovarian cancer or both. These decisions are personal ones, says Mott. It’s the counselor’s job to educate the mutation carrier about all options, and there’s no one-size-fits-all approach.
 
“Studies have shown that more than 85 percent of people who undergo genetic testing don’t have a cancer-causing mutation,” says Mott, again emphasizing that inherited cancer is rare.
 
What’s the risk of developing breast or ovarian cancer? Generally, a woman with no family history of breast cancer, who develops post-menopausal breast cancer, is considered to have developed a “sporadic” cancer. According to the National Cancer Institute, the average risk of developing breast cancer is about 12 percent over a woman’s lifetime and the average risk for developing ovarian cancer is 1.4 percent over a woman’s lifetime. In comparison, a woman with a mutation in either the BRCA1 or BRCA2 genes has much higher lifetime risks, ranging from 50 to 87 percent for breast cancer and from 27 to 50 percent for ovarian cancer.
 
“Genetic testing helps us identify individuals who are at significantly elevated risk of developing cancer. By identifying those at high risk, we’re able to offer evidence-based risk management strategies,” says Mott. “These options are important because research has proven the benefits outweigh the risks. You can’t make an informed decision without accurate information. And whether it’s having a genetic test or choosing a [medical] management strategy, you don’t have to make that decision alone.”
 

The future of genetic testing

While having your DNA tested may seem simple, there’s more to it than providing a blood or saliva sample. Understanding the results can be complicated and may open the door to many difficult—yet, potentially, life saving—decisions.
 
“There are more than 50 cancer genes that have been discovered,” explains Bowling. “The role of a genetic counselor is to evaluate the family history and determine which genetic test is most appropriate. And then interpret results while taking the patient’s personal and family history into account. Genetic testing, like medical tests, don’t stand alone.”
 
Today, advancements in genetic testing carry with them some ethical choices, as well, particularly because testing involves families.
 
“The science of hereditary cancer is rapidly changing. Two years ago, we were testing gene-by-gene, but now we have the option of testing varying numbers of genes through multi-gene panels,” says Mott. “Panel testing increases the importance of genetic counseling, because patients need to understand the possibilities, including an increase in uncertain results, prior to undergoing testing. Even with a detailed explanation, uncertain results can be anxiety producing.”
 
On the other hand, if you’ve had to face cancer and you’re concerned what this may mean for family members, test results and a family medical history can provide a beneficial tool to make informed decisions.
 
Marilyn, for example, has encouraged her three adult sons to be tested for the BRCA gene mutation she carries, and she considers the legacy of what DNA test results may mean for her three grandchildren someday. “My oldest son [now 42 years old], doesn’t want to be tested yet,” says Marilyn, who’s been cancer-free for five years. “But to me, it’s a life-saving tool.”
 
 

Building Your Family Medical History

 
Some of the most common diseases, such as cancer, heart disease, stroke and diabetes, often run in families. A family medical history is an inexpensive way to assess your personal risk and lets you take steps to better protect yourself. “An accurate family medical history that spans three to four generations is an extremely valuable tool in assessing a patient’s risk of developing a disease,” says Kathleen Mott, a genetics specialist at Redwood Regional Medical Group in Santa Rosa. So next time you’re with relatives, take the time to investigate your own family medical history. You can build a family health portrait with an online tool from the Surgeon General at https://familyhistory.hhs.gov/fhh-web/home.action.
 
 
 

When to Get Tested

 
According to North Bay health care providers, you may want to pursue genetic counseling if:
 
• You had breast cancer before age 50;
• You’ve had both breast and ovarian cancer;
• You had breast or ovarian cancer and have relatives with a history of breast and/or ovarian cancer;
• You are of Ashkenazi (Eastern European) Jewish ancestry and have a personal and/or family history of breast and/or ovarian cancer; or
• A family member has already had genetic testing that revealed a BRCA1 or BRCA2 mutation.
 
For more information, talk to your health care provider or go to http://demystifyingmedicine.od.nih.gov/DM10/0413-BreastCancer/NCCN%20br%20genetics_screening.pdf.

 

 

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