Nearly 30 percent of D.C. residents who received a colon cancer screening during a six-month study were found to have a precancerous lesion, a rate higher than the national average. Yet only a few residents took advantage of the free screening, prompting physicians to step up promotion of the program.

At a news conference Monday, Howard University and Georgetown University hospitals invited uninsured and under-insured men and women between 50 and 64 who live in the District to take advantage of the free screenings.

“Colon cancer is one of the deadliest cancers, but also one of the most preventable,” said Duane Smoot, chief of the Gastroenterology Division of Howard University Hospital Cancer Center and head of the DC Screen for Life program at the hospital.

According to the American Cancer Society, colon cancer is the fourth leading cancer in the nation; roughly 5 percent, or one in 20 people, will contract it. It is the second leading cause of death from cancer and strikes African Americans disproportionately.

Most colon cancer results from polyps in the large intestine, but the lesions are easily removed during a colonoscopy, the physicians said. Of the 150 people tested in the study, 45 were found to have adenomas or precancerous lesions, which left untreated can turn into cancer.

Smoot said physicians have no idea why African Americans are affected by colon cancer in such high numbers. He said diet, lack of exercise, a family history of cancer and lack of access to medical care may play a part. However, it is not only the poor and uninsured who fail to be screened, he added.

“Many people are of the mind that they don’t want people looking up there,” Smoot said of the exam, where doctors examine the inside of the intestine with a lighted probe that is threaded through the rectum after the patient has been put to asleep or sedated.

Doctors said people with family history of colon cancer are at a higher risk and need to be screened earlier.

Usually, the percentage of people in the general population found to have polyps during routine screening is 20 percent to 25 percent, if that, said Oscar E. Streeter, a radiation oncologist at Howard. “It really was a surprise to us that it was so high,” he said of those tested in D.C. “The next question is why.”

Streeter, who is African American, had a polyp removed in September. He said his mother-in-law died of colon cancer.

At the news conference, Streeter pointed out that a colonoscopy, including removal of any polyps, costs about $800 under the program compared with up to $64,000 for surgery, radiation and chemotherapy if a polyp is left untreated and becomes cancerous.

“The screenings are not only saving money, though, they are saving lives,” he said.

Adeyinka Laiyemo, a researcher at the National Institutes of Health and an attending physician at Howard's Cancer Center, urged blacks to research their families' medical history. While the American Cancer Society recommends screening for most people at age 50, those with a family history of the disease should be screened at 45, he said.

Joyce Byrd, 54, who received her second colonoscopy under the program, embraced Laura Song, a patient advocate at Georgetown. Byrd, the mother of three children, who lost her medical insurance three years ago when she was laid off, had a precancerous lesion removed previously, but was hesitant to get the screening a second time.

“She talked me into it,” she said, smiling at Song. “She may have saved my life.”

“She helped me, too,” said Song, 24. “I was talking to her her about the need for her to be be screened and she asked me about my own health. . . . She encouraged me and I went to have my first ob-gyn exam.”

To schedule an appointment call Howard University Hospital at 202-865-7741, or Georgetown University Hospital 202-469-2338.