1. Carcinoma Anal Canal
Dr Pavan Kumar Lachi
24 9 2013

2. Anatomy of anal region

3. Anatomy and histology of the anal canal
• Definition - the ‘‘surgical’’ anal canal from the anorectal ring (upper portion of the
puborectalis/levator complex) at the floor of the pelvis
to the anal verge. Appx 4 cm in length
The anal verge is the point at which modified squamous
epithelium (anoderm) of the anal canal meets hairbearing perianal skin.

4. Anatomy and histology of the anal canal
• The lining of the anal canal is divided into three
zones:
• Colorectal zone - proximally
• Anal transitional zone (ATZ, extending approx. 1
cm upward from dentate line)
• Squamous zone (extending distally from the
dentate line to the anal verge.

5. • The colorectal zone - columnar mucosa identical to the distal
rectal mucosa.
• The ATZ
- many epithelial variants, including squamous & colorectal
type mucosa
- ‘‘ATZ epithelium,’’- 4-9 cell layers including basal, columnar,
& cuboidal cells.
- Melanocytes and endocrine cells are also occasionally
found.
• The squamous zone - unkeratinized squamous mucosa without skin appendages.
- Melanocytes may also be present.

6. Anal verge
• The perianal skin contains sweat, sebaceous &
apocrine glands & is keratinized
• The anal margin - perianal skin extending
approx. 5- 6cm from the anal verge.
• All skin cancers can affect the anal margin .

7. 1

9. Epidemology – Anal cancer
• Anal cancers are about one-tenth as common
as cancers of the rectum.
• Cancers arise in the canal 3 to 4 times more
frequently than in the perianal skin.
• In North America and Western Europe
squamous cell cancers - 80% of anal cancers
• In Japan only 20% are squamous.

10. Risk factors of anal cancer
Old age
Common in female - 1:1.5 – 2
Cigarette smoking – fourfold increase of risk
A history of anal intercourse
sexually transmitted disease

11. • HPV infection.
• Human immunodefi ciency virus (HIV)
• Immunosuppression - tenfold risk is seen in
immunosuppressed
• Cancer of the cervix, vagina, or vulva
• Benign lesions of the anus (such as chronic
anal–rectal inflammation)

12. AIDS defining cancers
• Invasive ca cervix
• Primary CNS Lymphoma
• Kaposi sarcoma

14. Clinical Presentation
•
•
•
•
•
Bleeding per rectum
Perianal pain
Pruritus
A palpable mass
Change in bowel habit

15. Routes of spread – LOCAL EXTENSION
• Sphincter muscles
• Perianal connective
tissues
• Rectum
• Perineum
• Prostate
•
•
•
•
•
Perineal fossa
Perianal skin
Pelvic wall
Vaginal septum
Anal-vaginal fistula is
seen in <5% of cases

16. Lymphatic spread
• May occur early in disease
• Overall lymph node spread is seen in 25% of
cases at diagnosis
• Delayed inguinal lymph node metastasis is
seen in approximately 10–25% of patients

17. • Distant metastasis is relatively rare, and extra
pelvic metastasis is seen in <10% of patients
before treatment
Common sites of metastasis include
• Liver
• Lungs
• Extrapelvic lymph nodes

23. Prognostic factors
•
•
•
•
•
•
•
Advanced stage at diagnosis
Male gender
Age ≥65 years
Hemoglobin levels ≤10 g/l at presentation
Nodal metastasis at presentation
Poor performance status
Presence of HIV infection or AIDS

24. Management – Anal Canal Carcinoma
• For a long time APR remained the standard of
care for anal cancer.
Papillon et al
• In the early 1960s
• Introduced the concept - long-term local
control with definitive radiation therapy.

25. Chemo radiotherapy
• Nigro et al. In 1974
• First demonstrated complete pathologic
responses to concurrent
5-fluorouracil, Mitomycin C, and Radiation
therapy.

27. Surgery - Indications
• Has limited role in the primary treatment of anal
cancer
• Local excision can be considered only for selected
patients with well differentiated early-stage
(T1N0M0)
• SCC that is <40% circumferential involvement
• No sphincter involvement
• Abdominal peritoneal resection (APR) is reserved
for salvage after primary chemoradiotherapy
failure

28. Radiation therapy - Indications
• EBRT with concurrent chemotherapy is the
mainstay treatment for localized anal cancer
• RT alone can be reserved for stage T1N0M0
disease
• Palliation to primary or metastatic foci
Techniques
• EBRT using three-dimensional conformational
RT(3D-CRT) or IMRT
• Brachytherapy has no role in the treatment and is
associated with high incidence of anal necrosis

30. UKCCCR Trial
• Randomized 585 patients to either radiation
therapy (RT)alone or concurrent
chemoradiation therapy (CRT)
• RT alone used 45 Gy in 20 or 25 fractions over
4–5 weeks

31. UKCCCR Trial
• 5-FU - 1,000 mg/m2, days 1–4 or
750 mg/m2 days 1–5
continuous infusion
• Mitomycin C - 12 mg/m2 bolus on day 1
• During the first and last week of Radiotherapy

32. UKCCCR Trial
70%
60%
50%
40%
30%
20%
10%
0%
RT
Chemo RT
3 Year local control

33. UKCCCR Trial
• 3-Year local control rates (61 versus 36%, p <
0.001)
• Addition of chemotherapy produced a
reduction of 46% in local failure (p < 0.0001)
• No benefit of OS observed with CRT

34. Can we skip Mitomycin ?

35. RTOG 98-11 phase III trial for anal
cancer

36. Radiation Therapy Techniques
• Radiation fields should encompass
1. Tumor bed
2. Regional lymph node areas (including inguinal
nodes) for locoregional control
• The patient should be placed in the supine
position
• Full bladder
• A radio-opaque marker at the anal verge of the
edge of the tumor

37. • 3dCRT - planning using CT simulation with
small bowel contrast is highly recommended.
• Radiation therapy can be divided into three
phases
1. Entire pelvic field
2. Cone-down pelvic field
3. Tumor bed only

38. Initial radiation fields (AP/PA) to cover
the entire pelvis

39. AP/PA field (whole pelvis)
• Superior: Top of S1
• Inferior: The lower of anal verge or tumor with
3 cm margin
• Anterior lateral: To include lateral inguinal
nodes with 1.5 cm margin, determined by
bony landmark or lymphangiogram
• Posterior lateral: 1.5 cm lateral to the widest
bony margin of the true pelvis

40. Inguinal node involvement at
presentation

41. • Inguinal lymph nodes are a potential site for
metastatic dissemination.
• Inguinal involvement is demonstrated to be a
poor prognostic factor.
• Benefit of prophylactic inguinal irradiation
(PII) remains questionable because of the
potential serious long-term wound and lower
extremity complications.

44. Cone-down radiation fields (AP/PA) to
cover the inferior pelvis

45. AP/PA field (cone-down pelvis)
• Superior: Inferior border of sacroiliac joint
• Inferior: same as in the whole-pelvis fi eld
• Anterior lateral: same as in the whole-pelvis
field
• Posterior lateral: same as in the whole-pelvis
field

46. Tumor bed boost field(s)
• Primary tumor: gross tumor with 2- to 2.5-cm
margin
• Lymphadenopathy: gross disease with 2-cm
margin

47. Dose and Treatment Delivery
•
•
•
•
Conventional fractionation
30.6 Gy to the entire pelvis
14.4 Gy to the inferior pelvis
Boost to 54–59.4 Gy to gross tumor, with a 2–
2.5 cm margin is recommended for patients
with T3 or T4, N+ patients, or T2 disease with
gross residual after 45 Gy.

69. Anal margin neoplasms
Bowen’s disease
• Intraepidermal squamous cell carcinoma (SCC)
• Represents the extreme end of a spectrum of epithelial
dysplastic changes known as anal intraepithelial
neoplasia (AIN).
• AIN - dysplastic changes of the anal canal epithelium
• BD generally implies involvement of the perianal skin
• Human papillomavirus (HPV) - etiological agent
• HPV 16 found in 60% to 80% of pts with perianal
Bowen’s disease.

70. Anal margin neoplasms
Bowen’s disease
• May progress to invasive SCC in approximately 2% to
5% of cases .
• Presentation
- as an asymptomatic or mildly symptomatic
scaly, erythematous rash of the perianal area.
- Pruritus and burning of the skin are common
complaints
- May be found incidentally on examination of tissue
removed during other anorectal procedures.
.

71. Anal margin neoplasms
Bowen’s disease
• Diagnosis - by biopsy, and must be distinguished from
other conditions of the perianal area, including Paget’s
disease, melanoma,& other dermatoses.
• Histologic appearance –
- atypical epithelial cells involving the full thickness of the
epidermis, producing sharp demarcation with the normal
dermis.
- cells with large haloed hyperchromatic nuclei, so-called
‘‘bowenoid cells,’’
• Rx - cryosurgery, topical 5-fluorouracil (5-FU), argon laser
therapy, CO2 laser ablation, and photodynamic therapy .
• Rx of choice - WLE - negative microscopic margins.

72. Anal margin neoplasms
Bowen’s disease
• Small defects from WLE can be closed primarily or
covered by SSGs.
• Larger defects may require the use of V-Y, S-shaped, or
house-shaped advancement anoplasty .
• Careful clinical follow-up of longer than five years is
required
• Local recurrence has been reported as late as 111
months after surgery

73. Thank you

74. Discussion
• Response assesment after
chemoradiotherapy?
• ACT II trail…..inference
• Recent NCCN guidelines….regarding surgwery
after chemo radiation…..