Squamous cell carcinoma (nonkeratinizing squamous cell or basaloid carcinoma) is the most common cause of cancer of the anorectum. Basal cell carcinoma Basal Cell Carcinoma Basal cell carcinoma is a superficial, slowly growing papule or nodule that derives from certain epidermal cells. Basal cell carcinomas arise from keratinocytes near the basal layer, which are... read more , Bowen disease Squamous Cell Carcinoma in Situ Squamous cell carcinoma in situ is a superficial squamous cell neoplasm. Diagnosis is by biopsy. Treatment depends on the tumor’s characteristics and may involve curettage and electrodesiccation... read more (intraepidermal squamous cell carcinoma), extramammary Paget disease, cloacogenic carcinoma, and malignant melanoma Melanoma Malignant melanoma arises from melanocytes in a pigmented area (eg, skin, mucous membranes, eyes, or central nervous system). Metastasis is correlated with depth of dermal invasion. With metastasis... read more are less common. Other tumors include lymphoma Overview of Lymphoma Lymphomas are a heterogeneous group of tumors arising in the reticuloendothelial and lymphatic systems. The major types are Hodgkin lymphoma Non-Hodgkin lymphoma See table Comparison of Hodgkin... read more and various sarcomas. Metastasis occurs along the lymphatics of the rectum and into the inguinal lymph nodes.
Risk factors for anal cancer include the following:
Irradiated anal skin
People having receptive anal intercourse are at increased risk. Patients with HPV infection may manifest dysplasia in slightly abnormal or normal-appearing anal epithelium (anal intraepithelial neoplasia—histologically graded I, II, or III). These changes are more common among patients with HIV-infection (see Squamous cell cancer of the anus and vulva Squamous cell carcinoma of the anus or vulva AIDS-defining cancers in patients infected with HIV are Kaposi sarcoma Lymphoma, Burkitt (or equivalent term) Lymphoma, immunoblastic (or equivalent term) Lymphoma, primary, of central nervous system read more ). Higher grades may progress to invasive carcinoma. It is unclear whether early recognition and eradication improve long-term outcome; hence, screening recommendations are unclear.
Symptoms and Signs of Anal Cancer
Bleeding with defecation is the most common initial symptom of anal cancer. Some patients have pain, tenesmus, or a sensation of incomplete evacuation. A mass may be palpable on digital rectal examination.
Diagnosis of Anal Cancer
Sigmoidoscopy or colonoscopy
A flexible sigmoidoscopy or rigid anoscopy or sigmoidoscopy is done to evaluate the area. Skin biopsy by a dermatologist or surgeon might be needed for lesions near the squamocolumnar junction (Z line). Whenever rectal bleeding occurs, even in patients with obvious hemorrhoids or known diverticular disease, coexisting cancer must be ruled out.
Once anal cancer is diagnosed, staging by CT of the chest, abdomen, and pelvis; MRI; or positron emission tomography (PET) is required to rule out metastatic disease.
Treatment of Anal Cancer
Combination chemotherapy and radiation therapy (chemoradiation)
Sometimes surgical resection for treatment of refractory disease or recurrence
Chemoradiation is the initial therapy in most cases and results in a high rate of cure when used for anal squamous and cloacogenic tumors.
Tumor regression continues for up to 6 months after completion of chemoradiation (1 Treatment reference Anal cancer accounts for an estimated 9760 cases and about 1870 deaths in the United States annually ( 1). The main symptom is bleeding with defecation. Diagnosis is by endoscopy. Treatment... read more ). Observation for a complete response during this time period is acceptable before considering surgery.
Abdominoperineal resection is indicated when radiation and chemotherapy do not result in complete regression of the tumor or there is recurrent disease.
1. James RD, Glynne-Jones R, Meadows HM, et al: Mitomycin or cisplatin chemoradiation with or without maintenance chemotherapy for treatment of squamous-cell carcinoma of the anus (ACT II): A randomised, phase 3, open-label, 2 × 2 factorial trial. Lancet Oncol 14(6):516–524, 2013. doi: 10.1016/S1470-2045(13)70086-X
Drugs Mentioned In This Article
|JELMYTO, Mitosol, Mutamycin
|Platinol, Platinol -AQ