Flat, non-polypoid colorectal neoplasms (NP-CRNs) could have
a greater association with cancer compared with the more routinely diagnosed
type of colorectal polyps, a new study concluded.
The researchers from the Veterans Affairs Palo Alto Health
Care System, Palo Alto, California have published a study in the
March 5 issue of JAMA, according to which colorectal cancer can also arise from
NP-CRNs.
The problem is that due to their nature, the non-polypoid
colorectal neoplasms could be easily missed during the colonoscopy or computed
tomography colonography.
“As compared with surrounding normal mucosa, NP-CRNs appear
to be slightly elevated, completely flat, or slightly depressed,” the authors
write. Data are limited on the significance of NP-CRNs.
Roy M. Soetikno, M.D., M.S., and his colleagues have examined
data from a group of 1,819 patients undergoing elective colonoscopy to estimate
the prevalence of NP-CRNs and to characterize the association of NP-CRNs with
colorectal cancer.
According to their findings, the overall prevalence of
NP-CRNs was 9.35 percent. The prevalence of NP-CRNs in the subpopulations for
screening, surveillance, and symptoms was 5.84 percent, 15.44 percent, and 6.01
percent, respectively. The overall prevalence of NP-CRNs with cancer that had
not spread or had spread in tissue beneath the mucous membrane was 0.82
percent; in the screening population, the prevalence was 0.32 percent.
Overall,
NP-CRNs were nearly 10 times more likely to contain cancerous tissue than
polypoid lesions, irrespective of the size. They noted that up to 1 percent of
patients who have colonoscopies develop cancer within three years afterward.
These missed flat lesions may explain some of these cases, they said.
“In conclusion, in this population of patients at a single
Veterans Affairs hospital, NP-CRNs were a relatively common finding during
colonoscopy. They were more likely to contain carcinoma compared with polypoid
neoplasms, independent of lesion size. Recent studies have pointed out
differences in the genetic mechanisms underlying nonpolypoid and polypoid
colorectal neoplasms” the authors said.
Colon cancer is the second
most common cause of cancer-related deaths in the U.S., with more than 56,000 people
losing the battle each year. The American Cancer Society estimates almost
150,000 new cases of colorectal cancer for 2008 in the U.S. The
disease affects both men and women equally. Symptoms include changes and
bleeding during bowel movements, abdominal pain, severe weight loss, and
fatigue.
However, between 2002 and 2004, colon cancer death rates
have declined. In men, death rates have dropped 4.9 percent and in women, 4.5
percent, according to an annual report issued by the Nation on the Status of
Cancer. The decrease is accredited to better prevention and screening methods.