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.
She said the cancer changed her life, including sidelining her career. All the treatments, which included chemotherapy, deteriorated her body and affected her memory. She still has sensitivity in her fingers.
Porter, who lives in Cheverly, said she is in a better place in life now but used to wonder if things would have been different if her illness had been diagnosed earlier.
"Mad is not a strong enough word for how I felt," said Porter, now 52. "I felt robbed. I felt like it was unfair."
Patients under 50 don't seem to be dying at higher rates despite the more frequent diagnosis, research has found. Dr. You said that may be because their younger bodies can better withstand treatment.
In addition to lifelong bowel problems, younger survivors may have to deal with other side effects of the cancer, such as infertility issues caused by the radiation and other treatments used to fight the disease. Stotsky-Himelfarb, now 40, was able to preserve her eggs, but can't carry a baby, so she and her husband are looking for a surrogate.
Researchers have been debating ways to better address how colorectal cancer affects young people.
Dr. Durado Brooks, director of prostate and colorectal cancers at the American Cancer Society, said he doesn't believe lowering the age of screening is the answer because the tests are so invasive. Others say it would not be cost-effective to test everyone.
"If you are talking about looking at hundreds of thousands of people in their 30s and 40s for testing, the numbers of cancer cases you would find would be so small compared to the harm that you could cause some people through testing," he said.
Brooks and others said doctors and patients need to be better educated about the risk factors and symptoms so that the right young people can be tested. Doctors need to improve their efforts at collecting family history and patients need to be better at chronicling their medical history, Brooks said. Risk factors include family history, obesity, lack of exercise and a high fat diet.
Some doctors are using demographic data to pinpoint patients who may be more at risk.
Dr. Niraj Jani, chief director of gastroenterology at Greater Baltimore Medical Center in Towson, said he recommends African-American men get tested at 45 because they are at higher risk for colon cancer. He follows guidelines by the American College of Gastroenterology and the American Society of Gastrointestinal Endoscopy, which are more stringent than the more commonly used guidelines established by the U.S. Preventive Measure Task Force.
Jani said that it's still sometimes hard to get patients to see a doctor even when they have risk factors.
"People are sometimes afraid," Jani said. "If they don't know, they don't have to deal with it. But doctors have to be vigilant about getting their patients tested."