Colon and Small Bowel—Rectal Cancer
Concept
Prognosis worse than for colon cancer stage for stage.
Preoperative therapy offered to most patients except those with disease limited to the mucosa. Examiners will likely want to know when you will perform LAR, APR, and transanal excision.
Way Question May be Asked?
“62 y/o female with a history of painless rectal bleeding presents to your office for evaluation and on digital rectal exam, has an ulcerated mass beginning at 5 cm that appears fixed. What do you want to do?” May also be pre- sented with patient that has obstruction, pain, or bright red blood per rectum.
How to Answer?
History
Risk factors Pain
Change in bowel habits Rectal mass
Previous colorectal surgery
Continence status (don’t want to do restorative resection in pt with high likelihood of post-op incon- tinence)
Physical Exam
Digital rectal exam (is it fixed, where is the lesion from anal verge, size/circumference involved)
Lymphadenopathy (FNA any groin nodes if enlarged) Rigid Sigmoidoscopy (mobility of tumor and height
from anal verge)
Diagnostic Tests
Full labs (especially LFTs, CEA) CXR (r/o mets)
Colonoscopy (to evaluate rest of colon!)
Endorectal U/S (depth of invasion and lymph node status)
+/− CT scan (most would!) +/− Air contrast Barium Enema +/− MRI
Surgical Treatment
Remember try to get 2 cm margins (most agree 0.5 cm at minimum)
Always total mesorectal excision
LAR easiest for lesions in upper third of rectum If trying for lesions > 5 cm from anal verge, use colonic
J-pouch with coloanal anastomosis
Use loop ileosotomy for any anastomosis constructed less than 5 cm from anal verge (reversed at 8–12 weeks after gastrografin enema demonstrates no leak) Involved organs (uterus, adnexa, posterior vaginal wall,
bladder) removed en bloc
APR should be strongly considered for all invasive rec- tal CA < 5 cm from anal verge (closure of pelvic peritoneum not necessary, consider posterior vaginectomy in women with anterior tumors, have pt marked by stomal therapist pre-op)
Poor risk pts can be treated by radiation, and re-evalu- ation +/− fulgeration
Who gets Transrectal/Transanal Excision?
(must be mobile, non-ulcerated lesion)
< 3 cm in diameter
T1 lesions (muscularis propria too deep!) within 8–10 cm of anal verge
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Well to moderately differentiated tumor without ulcer- ation
No lymphatic invasion on pathology Less than 1/3 rectal circumference
Performed in prone-jackknife position and excise tumor with full thickness of rectal wall into perirec- tal fat with 1 cm circumferential margin (make sure to check path: r/o invasion of muscularis, lympho- vascular invasion, or poorly differentiated tumor) Orient carefully for pathologist
Who Gets Chemo/XRT?
(5-FU and Levamisole)
Rectal CA beyond the mucosa (Stage B, C, D)
Try to give XRT pre-op to spare small bowel (tattoo pre-op as tumor may “melt” away
(If local excision comes back stage II depth of invasion, post-op XRT to primary site and pelvis)
Common Curveballs
Testing your indications for local resection
Testing your knowledge of pre-op adjuvant therapy Post-op anastomotic leak
Post-op pelvic abscess
Being asked to describe surgical technique for an APR Local excision will come back with final pathology
Stage II depth of invasion Pt will have had prior colon surgery Pt will have IBD
Pt will have local recurrence (after local transanal exci- sion→ APR)
Positive margins after local transanal excision (re- excise!)
Injury to the ureter during LAR Post-op sexual dysfunction Presacral hemorrhage
Stomal complications with APR (stenosis, retraction, hernia, prolapse)
Invasion bladder/prostate/vagina
Strikeouts
Performing a local resection when not indicated Treating anal cancer like rectal cancer
Not doing staging work-up pre-op Not evaluating rest of the colon pre-op
Discussing transanal endoscopic microsurgery or endo- cavitary radiation
Attempting laparoscopically (current data support colon CA approached laparoscopically, but not rec- tal CA)
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