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