Internal Medicine

P1: SBT

0521779407-03 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 19:6

Anorectal Tumors 127

■More common in developed countries; associated w/ high-fat diet,

red meat consumption

■Anal canal tumors most commonly squamous cancer (∼70%) &

cloacogenic cancer

■Traditional predominance in women; now may be more common in

men due increased homosexuality

■Associated w/ HPV & receptive anal intercourse

Signs & Symptoms

■Rectal cancers usually present w/ bleeding, less often obstruction;

pain & significant change of bowel habits rare until advanced

■Squamous cancers present as palpable/visible lesions

■May be visible externally (anal canal tumors) or palpable if w/i

∼6 cm; sigmoidoscopy or colonoscopy usually used to make diag-

nosis

tests

Laboratory

■Anemia may be present (low MCV)

■? CEA late, usually sign of advanced disease, not helpful for screening

■LFTs not helpful for detection of occult liver metastases; CT much

more sensitive

■Consider HIV testing in pts w/ anal canal tumors

Imaging

■Remainder of colon must be screened w/ colonoscopy

■CT of abdomen & CXR/CT of chest to exclude distant metastases

(unless only palliative treatment undertaken)

■Endorectal US of rectal cancer may distinguish tumor stage (T,N),

which can be important for deciding treatment: local excision, low

anterior resection w/ anastomosis, abdominal-perineal resection

differential diagnosis

Consider Unusual Tumors:

■Rectum:

➣Carcinoid, GI stromal tumor, melanoma

➣Occasionally, ovarian cancer, prostate cancer, endometriosis

may mimic rectal cancer

■Anal canal:

➣Condyloma, KS, melanoma, Paget disease of anus

➣Consider HIV