Alimentary Tract - Anal Canal Flashcards
initial treatment of SCC of anal canal
concurrent chemoradiation (Nigro protocol)
radx dose - 45 Gy
chemo - mitomycin, 5-FU
If an anal margin/perianal skin SCC is well-differentiated and < 2 cm, what is first line treatment?
local excision if T1 and no risk to sphincter complex
6 months s/p chemoradiation, a patient has biopsy proven progressive/persistent anal SCC, what is the treatment?
APR
the surgical anal canal is between what two landmarks
intersphincteric groove
anorectal ring (not dentate line)
what structure is at the anorectal ring?
levator ani - divides the rectum and anal canal
the intersphincteric groove is between what structures?
the internal and external anal sphincter muscles
nonkeratinized squamous epithelium and keratinized squamous epithelium (external)
what is the difference in the anal canal proximal and distal to the dentate line
- Above the dentate: columnar epithelium; superior rectal artery, a branch of the inferior mesenteric artery; lymph drained along hypogastric vessels.
- Below the dentate: stratified squamous epithelium; inferior rectal artery, a branch of the internal pudendal artery; somatic innervation; superficial inguinal lymph drainage.
what studies are required for staging of anal SCC?
DRE, anoscopy, superficial inguinal node palpation w/ consideration of FNA, CT chest and abdomen, MRI pelvis, consider PET/CT if positive nodes or large mass
what are other studies that should be considered in patients who have already been staged for SCC?
HIV testing
in women, gyn exam should be considered to rule out HPV-associated cervical cancer
what is the recurrence rate for anal SCC after chemoradiation? when do you re-examine?
10-30%
wait 6 months to do biopsy (ongoing beneficial effects of radiation)
can do biopsy earlier if disease is progressing
for anal SCC, if there is biopsy-proven inguinal lymph node involvement, what else should be done at the time of APR
- pts initially receive chemoradiation that covers inguinal lymph nodes (positive or not)
- lymphadenectomy can be done during APR for pts with persistent or recurrent nodal disease
- lymph node involvement is an independent predictor of poor prognosis
what procedure would you do for a well-differentiated 1 cm SCC of the anus?
WLE +/- V-Y advancement flap or skin graft
what is the role of APR in anal SCC? what are the steps?
indicated for recurrent/progressing SCC 6 mo s/p chemoradiation
- goal: resect rectum, mesorectum, anus, perineal soft tissue, pelvic floor musculature en bloc
- abdomen: mobilize sigmoid, ID L ureter, divide sigmoid
- high ligation of IMA
- TME: circumferentx dissx in avascular plane around mesorectum, preserving autonomic nerve plexus
- perineum: elliptical incision, dissection to ischiorectal fossa
- end colostomy
in pts w/ SCC of the anus, what can be considered to prevent perianal wound complications (dehiscence, abscess, sinus tract)?
omental flap
muscle flap reconstruction (rectus abd, gracilis, gluteal)
how is radiation proctitis diagnosed? what can chronic radiation proctitis cause? how is it treated?
endoscopy w/ visualization telangiectasia, atrophy, friable tissue
can cause obstruction and bleeding
treated w/ sucrulfate, topical formalin, argon plasma
In a patient w/ anal SCC s/p chemoradiation, evidence of progression on examination should be followed by…
a biopsy and restaging with CT and/or PET.
Surgical treatment with an APR with or without inguinal node dissection is then indicated.
Surveillance of anal SCC involves evaluation by DRE, anoscopy, and inguinal lymph node palpation 8 to 12 weeks after completion of chemoradiation. At that time, patients’ conditions are classified as…
- complete remission - f/u w/ serial DRE, anoscopy, ILN palp, CT
- persistent disease - follow closely x6 mo - bx if still present
- progressive disease - bx, restage, APR +/- ILN dissx
A 51-year-old woman presents to your clinic with complaints of anal bleeding and pain. Physical examination reveals a 3-cm ulcerated anal lesion. What is your approach in evaluating this patient further?
- Ddx: cancer, infection, trauma
- PE: size, mobility, location in relation to sphincter, ILN
- Dx: biopsy
- Stage: FOBT, CT chest, MRI abd/pelvis, +/-PET/CT
A 64-year-old man is referred to you with squamous cell carcinoma of the anus. How would you determine the treatment plan?
- diffx b/w anal canal vs anal margin/perianal skin
- stage: DRE, anoscopy, MRI pelvis, CT chest/abd
- may need ILN FNA or PET/CT
- tx depends on stage
- differentiated, <2cm on margin - WLE
- Nigro treats everything else
- APR +/- ILN dissx if chemo fails (dz s/p 6 mo)
define anal intraepithelial neoplasia (AIN)
premalignant to anal SCC, SCC in situ, Bowen’s disease
exposure to what virus has been associated with the development of anal SCC
HPV
Other than HPV, what are other risk factors for anal SCC?
- STDs
- HIV
- immunosuppression
- smoking
- precancerous lesions
What is the differential for anal canal cancer?
SCC, melanoma, adenocarcinoma, carcinoid