Instead, they said her diarrhea, vomiting, cramping, iron deficiency and extreme fatigue were more likely caused by the flu, anxiety and even a brain disorder.
Misdiagnoses like Carr's are becoming more common as a disease historically associated with people older than 50 is increasingly affecting a younger population.
While overall rates of colorectal cancer have been dropping since the 1980s, cases in people under age 50 have been slowly, but steadily rising, research has found. The biggest increases come among people in their 40s.
Overall rates have been declining by about 3 percent per year in men and by 2.3 percent per year in women, according to the American Cancer Society. But colorectal cancer rates in people ages 18 to 49 increased 2.1 percent between 1998 and 2007.
While younger patients still make up a sliver of people who get the cancer, researchers and scientists are paying more attention before the problem worsens. It was a topic of discussion at a conference last week for the Colon Cancer Alliance in Baltimore.
Dr. Y. Nancy You, a surgical oncologist from Texas who spoke at the conference, said that most research on colorectal cancer skews toward older people. More wide-scale research on younger people needs to be done to better understand the new patterns of the disease, she said.
"It's hard to know whether the current research is really applicable to the younger population," she said.
Nobody really knows why the cancer is increasing in younger people.
Doctors believe lifestyle — including bad eating habits, lack of exercise and obesity — is part of the problem. Some of the answer probably also lies in genetics and environmental factors, doctors said.
Better screening and testing have helped over time to curb the disease, which is the third most commonly diagnosed cancer. Doctors are able to detect and remove polyps, sac-like growths on the colon wall, before they develop into cancer.
But guidelines generally call for screening people older than 50 and suggest younger people get tested only if they are showing signs of cancer and have a family history.
Even when younger patients have signs such as anemia and digestive complaints, doctors are more likely to attribute that to a medical problem other than cancer. Patients themselves may also wait to see a doctor because they might not connect the symptoms to cancer.
"I flip-flopped from doctor to doctor and tried treatment after treatment that would work for six months and then stop," said Eden Stotsky-Himelfarb, a nurse with the gastrointestinal surgical group at Johns Hopkins Hospital. She was diagnosed with stage 3 rectal cancer at age 26, but believes she was misdiagnosed for eight years. Stotsky-Himelfarb said she had a family history of cancer, including a grandfather who had colon cancer, that should have alerted doctors.
Carr is now 51 and cancer-free, but she remembers the frustration of being misdiagnosed. The sales engineer had three-fourths of her colon removed. Like many colorectal cancer survivors, she still deals with bowel problems. She said doctors need to be more aware of the symptoms of the disease and patients should be more proactive as well.
"If patients are showing symptoms, they need to be tested no matter their age," she said.
When it is finally diagnosed, the cancer in younger patients has usually progressed to a more advanced stage, making it more complicated and costly to treat, doctors said.
Dr. Laura Porter was diagnosed with stage 4 cancer at age 43 after experiencing several misdiagnoses. Training to become a doctor at the time, she was forced to drop out of her pediatric residency program after becoming sick. She would suffer two additional reoccurrences after her initial treatment.