Anal canal


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  • before 30 yearsold and multiple sexual partners (>10) are also identified asincreased risks for anal carcinoma
  • ~85% of cases demostrate human papilloma virus, High risk subtypes include type-16, -18, -31,-33, and -35. ,, or HPV infections(patients, particularly in patients whose CD4 count isless than 200, and those on immunosuppression after organ)may lead to immunodeficiency and further increase the risk of anal carcinoma
  • It is common for patients and their physicians to attribute such symptoms to hemorrhoids for many months preceding the diagnosis, underscoring the importance of performing a simple anorectal examination for patients with such symptoms.
  • Pattern of lymphatic spread depends on the location of the primary tumors
  • T4 for anal margin….deep extra dermal structure skeletal muscle or bone
  • Anal margin …N1 – I/L Inguinal LN, M1 – DISTANT METS
  • These authors reported the first large experience of
  • Break during radiation therapy for skin toxicity should not exceed 10 days. Total dose to the supplemental inguinal lymph node region is 36 Gy in clinically N0, and 45 Gy in N+ disease.A split course of radiation therapy is not recommended; although it is associated with lower incidence of severe toxicity, it may increase local failure and colostomy ratesis usually recommended to cover pelvic and inguinal lymph nodes.
  • Anal canal

    1. 1. Carcinoma Anal Canal Dr Pavan Kumar Lachi 24 9 2013
    2. 2. Anatomy of anal region
    3. 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. 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. 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. 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. 7. 1
    8. 8. 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.
    9. 9. 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
    10. 10. • 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)
    11. 11. AIDS defining cancers • Invasive ca cervix • Primary CNS Lymphoma • Kaposi sarcoma
    12. 12. Clinical Presentation • • • • • Bleeding per rectum Perianal pain Pruritus A palpable mass Change in bowel habit
    13. 13. 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
    14. 14. 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
    15. 15. • 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
    16. 16. 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
    17. 17. 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.
    18. 18. Chemo radiotherapy • Nigro et al. In 1974 • First demonstrated complete pathologic responses to concurrent 5-fluorouracil, Mitomycin C, and Radiation therapy.
    19. 19. 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
    20. 20. 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
    21. 21. 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
    22. 22. 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
    23. 23. UKCCCR Trial 70% 60% 50% 40% 30% 20% 10% 0% RT Chemo RT 3 Year local control
    24. 24. 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
    25. 25. Can we skip Mitomycin ?
    26. 26. RTOG 98-11 phase III trial for anal cancer
    27. 27. 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
    28. 28. • 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
    29. 29. Initial radiation fields (AP/PA) to cover the entire pelvis
    30. 30. 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
    31. 31. Inguinal node involvement at presentation
    32. 32. • 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.
    33. 33. Cone-down radiation fields (AP/PA) to cover the inferior pelvis
    34. 34. 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
    35. 35. Tumor bed boost field(s) • Primary tumor: gross tumor with 2- to 2.5-cm margin • Lymphadenopathy: gross disease with 2-cm margin
    36. 36. 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.
    37. 37. 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.
    38. 38. 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. .
    39. 39. 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.
    40. 40. 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
    41. 41. Thank you
    42. 42. Discussion • Response assesment after chemoradiotherapy? • ACT II trail…..inference • Recent NCCN guidelines….regarding surgwery after chemo radiation…..