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COLORECTAL CANCER Brian Kaplan
ANATOMY» LARGE INTESTINES˃ APPENDIX ˃ ASCENDING COLON˃ TRANSVERSE COLON˃ DESCENDING COLON˃ SIGMOID
Right Hemicolectomy
Transverse Mesocolon
RECTUM
» Peritoneum-˃ Upper third covered anteriorly and laterally˃ Middle covered only anteriorly˃ Lower none˃ Forms rectovesical and rectouterine space as reflects anteriorly
Rectum
RECTUM
Blood Supply» Superior Rectal» Middle Rectal» Inferior Rectal» Anastomosis
Venous Drainage» Parallels arteries» Dual Drainage» Superior rectal drains into
portal» Middle/Inf. –drain into
systemic
Anus» Starts at anorectal junction and end
at anal verge» Anal columns consist of longitudinal
folds» Superior border is anorectal line
which divides the rectum and anus» Inferior border is the dentate line» Dentate line divides columnar above
and squamous below» Sup. Rectal supplies the anus above
the dentate
Anus
» Innervation above dentate is same as the rectum –only sensitive to stretch
» Below the dentate the inferior rectal of the pudendal supplies the anus- pain touch temperature
COLONIC POLYPS
» Abnormal growth of mucosa» Pedunculated-stalk» Sessile-flat» Nonneoplastic polyps:
HyperplasticInflamatory-regenerating epitheliumJuvenile<10 years –hamartomas-distal colon
Adenoma to Carcinoma Sequence
» Series of molecular changes» Mutation in k-ras on chromosome 12 p is found
in 65% of sporadic colon ca» Deletions in APC gene (5q –tumor supressor
gene)
Table 46-1. CLASSIFICATION OF COLORECTAL POLYPS MUCOSAL POLYPSNeoplasticBENIGNAdenomatous polyps (dysplastic mucosa)TubularTubulovillousVillous MALIGNANTCarcinoma in situInvasive carcinomaPolypoid carcinoma NonneoplasticHyperplastic polypsJuvenile polypsPeutz-Jeghers polypsInflammatory polypsNormal epithelium SUBMUCOSAL POLYPSLipomasLeiomyomasColitis cystica profundaPneumatosis cystoides intestinalisLymphoid aggregatesLymphoma (primary or secondary)CarcinoidsMetastatic neoplasms
Adenoma-Carcinoma Sequence
Polyps and Cancer
Pedunculated vs Sessile
Syndromes
» FAP- thousand of polyps deletion APC gene (5q) IAA
» Colon ca at mean age of 35» Gardener’s –variant of FAP –osteomas, lipomas
and sarcomas» Turcot’s –brain tumors» Variable manifestations of mutation in same
gene
HNPCC
» Lynch syndrome» Autosomal dominant» Mutation on chromosome 2» Other cancers endometrial stomach and urinary
tract
» Peutz-Jeghers –hamartomas polyps associated with cutaneous pigmented lesions
» Low risk of malignancy» Cowden’s DZ hamartomas with facial epithelial
lesions-increased risk for breast cancer» Cronkhite Canada –hamartomas , alopecia
diarrheas and hyerpigmentation
STAGING
SURGERY
Adjuvant TX
» Radiation for rectal cancer» Generally recommended for pts with stage II dz» Colon ca-chemo for stage II/III» 5-FU/LV
Anal Cancer
» Squamous cell cancer» Bowen dz carcinoma in situ» Chemo /RT» Nigro Protocol» Excellent sphincter preservation
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