Surgery for Anal Cancer

Peter M. Sagar, Leeds General Infirmary

Powerpoint File

Bowen's Disease

Bowen's disease of the perianal skin is a rare, slow growing, intraepidermal squamous cell carcinoma (carcinoma in situ) first described by John T. Bowen in 1912 as a chronic atypical epithelial proliferation. It occurs most commonly in the sixth decade of life. The proposed relationship of this disease to the simultaneous or subsequent development of internal malignancies is noteworthy. Furthermore, 40% or more of the patients with Bowen's disease will develop other cutaneous pre-malignant and malignant lesions 6 or 7 years after the onset of Bowen's disease.

Clinical Features

Grossly, the lesions of Bowen's disease appears as discrete, erythematous, occasionally pigmented, noninfiltrating, scaly or crusted plaques, which sometimes have a moist surface. Foci of ulceration indicate that an invasive carcinoma has developed, a complication that occurs in approximately 6% of patients. Patients may complain of itching, burning or spotted bleeding, but only a biopsy will confirm the diagnosis.

Treatment

Wide local excision is the treatment of choice for patients with Bowen's disease. Beck recommends obtaining biopsies 1 cm from the edge of the lesion and in all four quadrants of the perineum because Bowen's cells may extend beyond the gross margin of the lesion. When he used wide local excision, there was no recurrence in 21 patients. Bowen's disease may extend into the anal canal, requiring wide excision of the anoderm. Even extensive disease that requires circumferential excision can be repaired with V-Y sliding flaps.

Perianal Paget's Disease

In 1874 Sri James Paget first described this disease in relation to the nipple of the breast in females. It was George Thin, in 1881, who was the first to describe the cytological features of Paget's cells, which appeared microscopically as large rounded cells with abundant pale-staining cytoplasm and a large nucleus that is often displaced to the periphery of the cell. The first case of perianal Paget's disease was reported by Darier and Couillaud in 1893. Extramammary Paget's disease may be found in the axilla and anogenital region (labia majora, penis, scrotum, groin, pubic area, perineum, perianal region, thigh and buttock).

Clinical Features

Perianal Paget's disease is an uncommon condition that is most commonly found in elderly people with an average age of 66 years. From 1963 to 1995 there have been 194 cases reported in the literature. The lesions appear as a slowly enlarging erythematous, eczematous and often sharply demarcated perianal skin rash that may ooze or scale and is usually accompanied by pruritus. Because of its similarity to other perianal conditions such as idiopathic pruritus ani, hydradenitis suppurativa, condyloma acuminatum, Crohn's disease, Bowen's disease and epidermoid carcinoma, the diagnosis of perianal Paget's disease is often delayed because of clinical diagnostic error. In almost one third of the cases in a series by Jensen et al., the lesion involved the entire circumference of the anus.

Diagnosis

The diagnosis must be confirmed by biopsy and by identification of the characteristic Paget's cells through histological examination.

Treatment

In the absence of invasive carcinoma, wide excision is the treatment of choice. Obtaining an adequate microscopically clear margin is important. Because perianal Paget's disease may extend beyond the gross margin of the lesion, mapping the extent of involvement by obtaining multiple biopsies 1 cm from the edge of the lesion in all four quadrants, including the dentate line, the anal verge, and the perineum is recommended. Similar to Bowen's disease, extensive perianal Paget's disease requires a circumferential wide excision of the perianal skin.

Squamous Cell Carcinoma

Clinical Manifestations

The presentation of squamous cell carcinomas generally follows a long history of minor perianal problems, such as bleeding, which occurs in approximately 50% of the patients. Other signs and symptoms include pruritus, discharge, pain and an indurated anal mass. Discharge, incontinence, change in bowel habit, pelvic pain and anovaginal fistula suggest advanced lesions with involvement of the anal sphincter. Almost one third of the patients in the series of Stearns and Quan were initially incorrectly diagnosed as having benign or inflammatory disease.

Treatment

Local Excision. This form of therapy should be reserved for early carcinomas or the well-differentiated type that has invaded only the submucosa.

Abdominoperinal Resection. In the past, abdominoperineal resection with wide excision of perineal tissue formed the basis of treatment. Despite this aggressive approach, the results have been disappointing. The local recurrence rate is 27% to 50% and the 5 year survival rate ranges from 24% to 62^ with a perioperative mortality rate of 2% to 6%. An abdominoperineal resection is no longer the primary treatment for invasive squamous cell carcinoma of the anal canal. Abdominoperineal rsection is reserved for those patients who cannot tolerate the chemoradiation and is the primary treatment for failed chemoradiation.

Pattern of Failure and Treatment. The predominant sites of failure after chemoradiation are the pelvis, either the anal area or the regional lymph nodes In a series of 190 patients reported by Cummings et al., 41% experienced recurrence at one or more sites. Of those recurrences, 62% were confined to the pelvis, 16% were outside the pelvis and the rest occurred both inside and outside the pelvis. Those patients with residual or recurrence carcinoma confined to the pelvis or perianal area should undergo a salvage abdominoperineal resection with or without a booster dose of radiation. The outcome is significantly related to the extent of the disease at the time of failure. The series from Memorial Sloan-Kettering Cancer Center showed that T stage did not appear to affect survival after abdominoperineal resection (p = 0.07). Inguinal node metastasis at initial presentation, before the chemoradiation, predicted poor outcome after abdominoperineal resection for treatment failure. Patients with disease fixed to the pelvic side wall on digital examination at the time of treatment failure fared poorly, with an 8 month median survival and no 5 year survival. Among those with mobile lesions, the median survival is 40 months, with an overall 5 year survival of 57% of those patients. Longo et all. showed that the salvage abdominoperineal resection following recurrence had a curative potential, but their follow up was short. A dismal result was described by the series of Zelnick et al. where there was no 5 year survival.

Inguinal Lymph Node

Because of the high morbidity and low yield in the prevention of death from cancer, prophylactic groin dissection is not recommended. The simultaneous appearance of inguinal metastasis is an ominous sign. In the series of Stearns and Quan, only 2 of 14 patients survived for 5 years. In contrast, the subsequent appearance of inguinal metastasis provides a better outlook. Fifteen of 20 such patients survived for 5 years after radical groin dissection. The treatment of inguinal node metastasis is chemoradiation to the inguinal area. On the other hand, Papillon and Montbarbon treated inguinal node metastasis with a limited groin dissection followed by treatment with radiation of 4500 cGy.

Melanoma

Malignant melanoma is the most depression of all anorectal malignancies. It is a rare malignant neoplasm of the anorectum that constitutes 1% to 3% of all melanomas. The anal canal is the third most common site, exceeded only by the skin and dyes. The female-to-male ration is approximately 2:1, and the average age at presentation is approximately 63 years. Malignant melanoma arises from epithelium of the anal canal, both above and below the dentate line. A few reports describe these lesions as arising from and being situated in the rectum. A recent study using electron microscopy revealed that normal melanocytes are present in the rectal mucosa.

Clinical Features

Rectal bleeding, a mass in the anal canal, and anorectal pain are the three most common and consistent signs and symptoms of malignant melanoma. Only 25% of patients have lesions <1 cm in diameter. The remainder have melanomas as large as 6 cm in diameter, with an average size of 4 cm. Often the mass protrudes through the anus. Weight loss is also a common finding.

Diagnosis

Melanomas are suspected when a pigmented polypoid lesion is noted. Unless an ulceration with raised edges is present, this disease may be confused with a thrombosed haemorrhoid.

Treatment

Melanomas of the anal canal are radioresistant and do not respond to chemotherapy or immunotherapy. For the majority of cases, there appears to be no clear-cut choice of surgical treatment between a wide local excision and an abdominoperineal resection. Both treatments yield a 5 year survival between 0% and 22%. Thibault et al. reviewed the series from the Mayo Clinic attempting to find predictive factors of survival, including gender, size of the lesion, presence of melanin, depth of penetration, positive perirectal lymph nodes, wide local excision vs. abdominoperinal resection and there was none. This is in contrast to the find by Brady, Kavolius and Quan at Memorial Sloan-Kettering Cancer Center that all long-term survivals occurred in women. Indeed, in their study, women with operable disease had a 5 year survival rate of 29%. Although the authors recommend an abdominoperineal resection, only one of nine patients who underwent such an operation had positive mesenteric nodes. It appears that local control of the disease after the operation is not as much a problem as distant metastasis, which is the major cause of death. A reasonable approach is to perform local excision of the lesion, if this can be accomplished with wide margin and full thickness without causing faecal incontinence. Otherwise, an abdominoperineal resection should be performed.

References

1. Bowen JT. Precancerous dermatoses: A study of two cases of chronic atypical epithelial proliferation. J Cutan Dis 30:241-255, 1912.

2. Graham JH, Helwig EB. Bowen's disease and its relationship to systemic cancer. Arch Dermatol 83:738, 1961.

3. Beck DE. Paget's disease and Bowen's disease of the anus. Semin Colon Rectal Surg 6:143-149, 1995.

4. Paget J. On disease of the mammary areolar preceding cancer of the mammary gland. St. Barth Hosp Rep 10:87-89, 1874.

5. Tjandra J. Perianal Paget's disease. Report of three cases. Dis Colon Rectum 31:462-466, 1988.

6. Darier J, Couillaud P. Sur un cas de maladie dePaget de la region kerineo-anal et scrotale. Ann de Dermatole et de Syph 4:25-31, 1893.

7. Stearns MW Jr., Quan SHQ. Epidermoid carcinoma of the ano-rectum. Surg Gynaecol Obstet 131:953-957, 1970.

8. Gordon PH. Current Status - Perianal and anal canal neoplasms. Dis Colon Rectum 33:799-808, 1990.

9. Cummings BJ, Keane TJ, O'Sullivan B, Wong ES, Cotton CN. Epidermoid anal cancer: Treatment by radiation alone or by radiation and 5-fluorouracil with and without Mitomycin C. Int J Radiat Oncol Biol Phys 21:1115-1125, 1991.

10. Ellenhorn JD, Enker We, Quan SHQ. Salvage abdominoperineal resection followed combined chemotherapy and radiotherapy for epidermoid carcinoma of the anus. Ann Surg Oncol 1:105-110, 1994.

11. Papillon J, Montbarton JF. Epidermoid carcinoma of the anal canal. A series of 176 cases. Dis Colon Rectum 30:324-333, 1987.

12. Thibault C, Sagar P, Nivatvongs S, Wolff BF. Anorectal melanoma: An incurable disease? Dis Colon Rectum 30:661-668, 1997.