Like many people adopted as children, Heidi Watts became curious about her own past after having children, and went looking for her birth mother.
At the age of 37, she found her. Ms. Watts also learned, among other things, that her birth mother had been diagnosed with colorectal cancer when she was 40. So had her grandfather and great-grandmother. With that unusual family history, Ms. Watts immediately went for testing and learned that she, too, had cancerous polyps in her colon.
"I was lucky. My cancer was caught early," Ms. Watts, who lives in Whitby, Ont., said in an interview. Nonetheless, she had her colon removed. Today she is in excellent health.
While colorectal cancer tends to strike later in life -- it is recommended everyone older than 50 be screened annually -- Ms. Watts has a hereditary form of the disease known as Lynch syndrome.
A new study, published in today's edition of the New England Journal of Medicine, recommends everyone diagnosed with colorectal cancer also undergo genetic testing for Lynch syndrome.
Dr. Heather Hampel of the cancer genetics program at Ohio State University in Columbus, Ohio, said although only about 5 per cent of colorectal cancers are inherited (and half of these are Lynch syndrome), large-scale testing is justified because it could identify many cancer cases that would otherwise not be detected early.
A confirmed diagnosis of Lynch syndrome also changes treatment, because that form of cancer reacts poorly to some forms of chemotherapy. Further, there are broader implications for people with inherited colorectal cancer (women, in particular) because the genetic mutation also predisposes them to brain tumours, ovarian and endometrial cancer. (Ms. Watts, for example, had a hysterectomy because of her high cancer risk.)
"Routine molecular screening . . . for Lynch syndrome identified mutations in patients and their family members that otherwise would not have been detected," Dr. Hampel said. "These data suggest the effectiveness of screening."
The study involved 1,066 patients who were diagnosed with colorectal cancer at major hospitals in Columbus. Of that total, 23 patients, or 2.2 per cent, had Lynch syndrome, which is known more formally as nonpolyposis colorectal cancer. Of the 23, researchers found that 10 were older than 50, and five did not meet existing guidelines for diagnosing Lynch syndrome.Genetic testing and counselling was offered to all relatives of those found to be at risk. A total of 117 relatives took the test; 52 were found to have Lynch syndrome, including 14 who had undetected colorectal cancer.
In the United States, about 148,000 people are diagnosed with colorectal cancer annually. Based on the data, at least 2 per cent, or 2,960 people, have Lynch syndrome; an average of three other family members could be identified with testing. All told, that means about 11,840 people could be diagnosed with Lynch syndrome annually in the U.S., Dr. Hampel said.
An estimated 19,600 Canadians will be diagnosed with colorectal cancer this year. Based on the U.S. data, genetic testing would identify 1,568 cases of Lynch syndrome.
In a commentary also published in today's edition of the New England Journal of Medicine, Dr. Henry Lynch of the Creighton University School of Medicine in Omaha, Neb. (and the researcher after whom the syndrome was named), said the findings are intriguing but leave many unanswered questions, chief among them who will pay for testing.
The genetic test costs more than $2,000 (U.S.). Even a cruder test that could help determine who should have a genetic test is $300. "Should either test be performed routinely among all patients with colorectal cancer? Probably not," Dr. Lynch said.
Ms. Watts understands that reluctance, saying there is a "real emotional impact to being diagnosed" with Lynch syndrome, which carries a 60- to 80-per-cent risk of developing colorectal cancer.
Nevertheless, she said her son and daughter, ages 15 and 14 respectively, will undergo testing when they reach 18 to ensure they have the best possible chance to lower their risk. In Ontario, the test is covered by provincial health insurance.
André Picard