Non-Polyploid Colon Regions Are Linked To Colorectal Cancer - And More Common Than Previously Thought

Flat,
non-polyploid colorectal neoplasms (NP-CRNs) are difficult to detect,
but when examined, they appear to be common. Additionally they may have
a stronger association with colorectal cancer than polyps, which are
more routinely observed in examination, according to a study published
on March 5, 2008 in JAMA



Colorectal cancer, sometimes
simply called colon cancer, encompasses cancerous growths in the large
intestines and appendix. It is the second leading cause of cancer death
in the United States. Prevention strategies have focused on detecting
and removing polyploid neoplasms, which are abnormal growths resembling
polyps. More recently, however, it has been shown that colorectal
cancer can develop from NP-CRNs, which are flat or depressed
in
shape. These can be more difficult to detect, according to the authors
of the study: "Nonpolypoid colorectal
neoplasms are more difficult to detect by colonoscopy or computed
tomography colonography because the subtle findings can be difficult to
distinguish from those of normal mucosa [membrane]. As compared with
surrounding normal mucosa, NP-CRNs appear to be slightly elevated,
completely flat, or slightly depressed."



Since information is
limited regarding the true significance of NP-CRNs in colorectal cancer
development, Roy M. Soetikno, M.D.,
M.S., and colleagues with the Veterans Affairs Palo Alto Health Care
System, Palo Alto, California, investigated data from 1,819 patients
undergoing elective colonoscopy, in the hope of estimating the
frequency of NP-CRNs and to characterize the relationship of NP-CRNs to
colorectal cancer.



Patients were also classified into subgroups according to their
situations: the screening group, of asymptomatic
patients who had undergone average risk-screening colonoscopies; the surveillance
group, who had a personal or hereditary history of colorectal cancer;
or the symptomatic
group, who showed symptoms and indications associated with colorectal
neoplasms, including anemia, rectal bleeding, constipation, diarrhea,
positive results from a fecal occult blood test, weight loss, abdominal
pain, and inflammatory bowel disease.



In the whole group, NP-CRNs were present in 9.35% of patients.
According to subpopulation, the screening group showed 5.84%,
surveillance showed 5.84%, and symptomatic showed 6.01%. In cancers
that had not spread, or had spread in the tissue beneath the mucous
membrane the overall prevalence was 0.82%, while prevalence in the
screening population was 0.32%. It was also observed in the
surveillance and screening populations.



Overall, NP-CRNs were almost 10 times more likely to contain cancerous
tissue than polyploid lesions, regardless of size. The
depressed type of NP-CRNs showed the highest risk (33%.) NP-CRNs
containing cancer were generally smaller in diameter when compared with
polyploid cancerous regions.



"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. Future studies on NP-CRNs should further evaluate
whether the diagnosis and removal of NP-CRNs has any effect on the
prevention and mortality of colorectal cancer and particularly focus on
their genetic and protein abnormalities," write the authors.



Editorial: Nonpolypoid Colorectal Neoplasia in the United
States



David Lieberman, M.D., of Oregon Health
& Science University, Portland VA Medical Center, Portland,
Ore.,
contributed an additional editorial in which he comments on the
findings of Soetikno and colleagues. "[Nonpolypoid
colorectal neoplasms] may be biologically distinct from polypoid
lesions and appear to be more likely to harbor malignant features.
Detection and complete removal at colonoscopy may be challenging. The
current study emphasizes the importance of quality in the performance
of colonoscopy," he writes. "The optimal methods for enhancing
colonoscopic imaging of NP-CRNs are uncertain. ??¦ Additional studies are
needed to determine whether imaging modalities such as computed
tomography colonography will be able to detect NP-CRNs. Finally,
longitudinal studies are needed to determine whether patients with
NP-CRNs require more intensive colonoscopic surveillance compared with
patients with polypoid lesions of similar size and histology."



Prevalence of Nonpolypoid (Flat and Depressed) Colorectal Neoplasms in
Asymptomatic and Symptomatic Adults

Roy M. Soetikno; Tonya Kaltenbach; Robert V. Rouse; Walter Park;
Anamika Maheshwari; Tohru Sato; Suzanne Matsui; Shai Friedland

JAMA. 2008; 299(9):1027-1035.

Click
Here For Abstract



Nonpolypoid Colorectal Neoplasia in the United States: The
Parachute Is Open

David Lieberman

JAMA. 2008; 299(9):1068-1069.

Click
Here For Extract



Anna Sophia McKenney

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