Genetic Testing for Colorectal Cancer
For a Broadway performer in her 40's, knowing about her genetic risk gave her the opportunity to choose her path and be proactive about her care.
"L" could be considered very lucky. At age 40, the Broadway performer, singer, and voice coach had a colonoscopy and some precancerous polyps removed.
The following year, her colonoscopy was clean. Two years later, when she became anemic, she should have had another colonoscopy, but put it off.
It was the illness of a close cousin, a 49 year old cardiologist, that soon set the wheels of life-altering discovery in motion.
Otherwise very healthy, L's cousin was suddenly diagnosed with advanced colon cancer. Genetic tests identified the presence of a mutation in a gene called MSH2, linking his illness to hereditary non-polyposis colon cancer (HNPCC), or Lynch syndrome. His father (L's uncle) was found positive for the gene as well.
The family quickly began putting the pieces together.
L's mother had died in 1985 from what had initially been labeled cancer of the gall bladder, but her pathology samples, not yet discarded, were now reanalyzed: they tested positive forMSH2 as well.
It was remembered that L's maternal grandmother died of endometrial cancer.
L soon sought genetic testing and counseling with Wendy Chung, MD, PhD, Director of Clinical Genetics at NewYork-Presbyterian/Columbia.
From the genetic tests, analysis of L's mother's samples, and family history emerged a picture of a strong line of the inherited Lynch syndrome, in this case caused by MSH2 abnormalities.
L and her youngest sister tested positive for the mutation of MSH2, while their middle sister was negative.
Some doctors urged L and her youngest sister to undergo hysterectomies to prevent the development of ovarian and endometrial cancer.
At this juncture, L and her sister chose quite different paths.
Her sister, married with two children, opted to undergo the hysterectomy.
She would still need to be regularly screened for colorectal cancer.
L, on the other hand, worked with the genetic counselors at NewYork-Presbyterian/Columbia and decided upon the path of continuous monitoring rather than surgery.
Every six months she has a thorough checkup, with more intensive yearly testing, including colonoscopy, endoscopy, sonogram, and blood tests, to detect the early signs of cancer that will remain a threat for the rest of her life. So far, L remains cancer free, and is satisfied that she made the right decision for herself.
Not all patients are as ready as L to undergo genetic testing or to share such information with their families.
Another of Dr. Chung's patients, a Russian woman in her 50's, also learned that she carries a genetic mutation for HNPCC.
She has had multiple surgeries to remove cancerous polyps and lesions, and she knows that her risk of other cancers is higher because of her genetic disposition.
But her family is currently dealing with her husband's prostate cancer, and she does not want her adult daughters to worry about their risk of cancer.
So for now, she has not divulged her test results, or shared that they have a 50% chance of carrying the same mutation.
L is glad she made the decisions she did, and she remains open to the possibility of a hysterectomy when she reaches menopause.
"My sister and I are very supportive of each other's unique decisions," she says.
"There are many different paths you can takesome are better for some people."
But for L, the choice to undergo genetic testing was never in doubt.
"I had always suspected something, and it's good to know (about the genetic risk) so I can be proactive.
Everyone is predisposed to somethingthere is no harm in finding out.
The more we share information, the better we can treat things.
Colon cancer is easy to discover and take care of, if it is found early," says L.
A small percentage of colon cancers are caused by a rare inherited disease called Lynch Syndrome, or Hereditary Nonpolyposis Colon Cancer (HNPCC).
The syndrome, caused by mutations of certain genes (MSH2, MLH1, MSH6, PMS1, or PMS2), causes carriers to have about an 80% lifetime risk of developing colon cancer, as well as an increased risk of endometrial, ovarian, gastrointestinal, hepatobiliary, and other cancers.
While people without the syndrome who develop colorectal cancer are typically diagnosed during their mid-sixties, those with HNPCC are diagnosed at an average age of 44.
Children of those with HNPCC have a 50% chance of inheriting the gene from a parent who carries it.