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COLONOSCOPIC
DIAGNOSTICS OF ADVANCED COLORECTAL ADENOMA
A.
Nagorni1, V. Katić2,
J. Milanović1,
S. Radić3,
G. Bjelaković1,
V. Živković2,
S. Ćirković3
1Clinic
for gastroenterology and hepatology, Clinical Center Niš, Serbia
and Montenegro,
2Institiute
for pathology, Clinical Center Niš, Serbia and Montenegro,
3Clinic
of oncology, Clinical Center Niš, Serbia and Montenegro
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ABSTRACT
It
is known that the vast majority of colorectal cancers (CRC) arise
from precursor lesions, benign adenomatous polyps or adenomas. Progression
of adenoma to CRC is multistep process, accompanied by alterations
of several suppressor genes that result in abnormalities of cell
regulation, with a natural history of 10-15 years. The adenoma-carcinoma
sequence postulates that adenomas contain dysplastic epithelium,
which arises from mutations in different genes. Recently literature
has adopted the term "advanced colorectal adenoma" to describe colorectal
polyps greater than 1 cm in diameter and/or villous component and/or
severe dysplasia, features predicting an increased likelihood of
malignant transformation. Advanced neoplasm was defined as CRC or
previously described advanced colorectal adenoma. There is no doubt
that advanced colorectal adenomas are link in a chain from benign
adenoma through malignant altered adenomas to advanced CRC. Synchronous
colorectal tumors are common finding during colonoscopic evaluation
of the large bowel. In 20-50% of patients synchronous adenomas are
detected. Prevalence of multiple colorectal adenomas grows with
aging. Multiple colorectal adenomas tend to be clustered in multiple
regions in any segment of the large bowel, less in rectum. It is
considered that cause of clustering of adenomas is potentially local
response to growth of single adenoma.Synchronous CRC are detected
in 1.5-14.7% of patients. Primary goal of early detection of CRC
and prevention of CRC is detection of all colorectal tumors, especially
malignant altered adenomas and advanced colorectal adenoma. In retrospective,
five-year study we examined 170 patients with colorectal tumors
(105 males, 65 females; age range, 34-77 years, mean, 57.6 years).
Colorectal polyps were removed by snare. Patients with incomplete
colonoscopy, inflammatory bowel disease, history of benign and malignant
colorectal tumors and patients with family history of CRC, breast
or ovarian cancer were excluded from the study. In 170 patients
colonoscopy was detected 325 large bowel tumors. Synchronous colorectal
tumors were found in 95 patients (60 males, 35 females; aged 35-75
years, mean 56.7 years). There were 3 patients´ subgroups: synchronous
benign tumors, synchronous CRC and synchronous benign tumors and
CRC. Synchronous benign adenomas were detected in 50 (52.63%) patients,
synchronous benign and CRC in 35 (36.84%) and synchronous CRC in
10 (10.53%) patients. Synchronous benign adenomas and synchronous
benign and malignant tumors were more frequent finding than synchronous
CRC (p< 0.001). We analyzed only patients with adenoma (85) in regard
to advanced colorectal adenoma. Advanced colorectal adenomas were
found in 22 (44%) patients with synchronous adenomas and in 20 (57.14%)
patients in mixed group of synchronous benign and malignant tumor.
In 54.54% of patients of synchronous adenomas was distal finding
during colonoscopy (rectum sigmoid, descending). In less than a
50% patients with synchronous benign and benign and malignant colorectal
tumors finding of advanced colorectal adenoma was marker of proximal
synchronous tumor growth (benign or malignant). The preliminary
results of this study confirmed hypothesis that index advanced colorectal
adenoma, especially in rectum and left colon is marker for proximal
synchronous growth, CRC or adenoma. Only diagnostics of all colorectal
tumors of different nature and polypectomy of all adenomas will
remove polyps and stopped development of adenoma-carcinoma sequence.
Polypectomy of advanced colorectal adenoma, which are link in a
chain from adenoma to CRC (just close to CRC), will directly prevent
development of CRC. Removing of all colorectal polyps, especially
malignant altered adenoma, advanced colorectal adenoma, and high-grade
dysplasia adenoma will prevent development of so called metachronous
CRC. In most cases with partial colonoscopy metachronous CRC were
missed synchronous CRC or advanced or malignant altered adenomas,
which transformed in CRC during the time. |
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Keywords:
Multiple CRC, synchronous and metachronous CRC, adenomas, colonoscopy
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