Malignant Neoplasms of the Anal Canal

Malignant tumours of the anal canal are rare and diverse group of tumours of gastrointestinal tract and comprises of 2.5 percent of all digestive system malignancy in United States. Although incidence rates are still low, there has been a significant increase in squamous cell carcinoma over the last 50 years. HIV infected homosexual men appear particularly at risk. HPV DNA is detectable in most anal squamous cell carcinomas. Despite its short length, the anal canal produces a variety of tumour type’s reflecting its complex anatomic and histological structure. Squamous, glandular, transitional, and melanocytic components occur at this site, either alone, or in combination. Due to the paucity of this malignancy it has been difficult to establish generally accepted guidelines for treatment. While for some neoplasms, the treatment of choice is clear-cut, for others it is still controversial. This review article makes an attempt to clarify current clinical, pathological and therapeutic options for anal canal tumors in the light of recent information.

2018

Malignant tumors of the anal canal are considered to be a rare neoplasm represents 0.43% of all malignancies and 2% of the digestive tract malignant tumors [1,2]. Overall, the most common cancer of the anal canal is squamous cell carcinoma (85%), followed by adenocarcinomas (10%). The other rare types such as melanoma, basaloid carcinoma and lymphoma represent less than 5% of all diagnosed tumors of the anal canal [2].

Diseases of the Colon & Rectum, 1986

From 1968 to 1982, 195 patients with invasive cancer of the anal canal were treated (average age, 67 + 11 years; range, 38 to 85 years; sex ratio [women/men]: 5/1). Histology revealed: cloacogenic cancer, 20 cases; squamous cancer, poorly differentiated, 30; moderately differentiated, 68; well differentiated, 77. The initial size of the cloacogenic cancers was smaller than the squamous cancers. Invasion less than half the circumference of the canal was 90 and 74 percent, respectively. No patients with cloacogenic cancer presented with positive inguinal nodes; however, there were 22 unilateral and five bilateral positive nodes in the squamous cancers. All 195 patients received radiotherapy as the first treatment. There were no differences among the patients operated on with respect to sterilized operative specimens, postradiotherapy sequelae, perineal recurrences, and/or visceral metastases in the cloacogenic and squamous cancers. Five-year survival was better in cloacogenic (62 percent) than in squamous cancers (56 percent); this difference was not significant, and was related to the initial size of the tumor. The number of patients with no evidence of disease and good anal function was significantly related to the initial size of the tumor, and was independent of the histoiogic findings.

International Journal of Surgical Oncology, 2020

Background. Anal canal adenocarcinoma (AA) is an uncommon tumor of the gastrointestinal tract. We seek to provide a detailed description of the incidence, demographics, and outcome of this rare tumor in the United States. Methods. The data on anal canal adenocarcinoma from SEER Program, between 1973–2015, were extracted. We analyzed the incidence rates by demographics and tumor characteristics, followed by analysis of its impact on survival. Results. The incidence of AA increased initially by 4.03% yearly from 1973 to 1985 but had a modest decline of 0.32% annually thereafter. The mean age for diagnosis of AA was 68.12 ± 14.02 years. Males outnumbered females by 54.8 to 45.2%. Tumors were mostly localized on presentation (44.4%) and moderately differentiated (41.1%). Age generally correlated with poor overall cancer survival. However, young patients (age <40 years) also showed poor long-term survival. Patients with localized disease and well-differentiated tumors showed better su...

Oncology Reviews, 2009

There are around 5,000 new cases of anal canal cancer each year in the United States. It is of particular risk in HIV-positive populations. Many cases are related to persistent infection with human papillomavirus (HPV). The treatment of anal cancer has progressed from abdominoperineal resection mandating permanent colostomy in the 1940s through the 1970s to modern chemoradiation with sphincter preservation

The American Surgeon, 2013

Small cell, neuroendocrine tumors, and melanoma of the anus are rare. Limited data exist on the incidence and management for these rare tumors. A large, prospective, population-based database was used to determine incidence and survival patterns of rare anal neoplasms. The Surveillance, Epidemiology and End Results registry was queried to identify patients diagnosed with anal canal neoplasms. Incidence and survival patterns were evaluated with respect to age, sex, race, histology, stage, and therapy. We identified 7078 cases of anal canal neoplasms: melanoma (n = 149), neuroendocrine (n = 61), and small cell neuroendocrine (n = 26). Squamous cell carcinoma (SCC) (n = 6842) served as the comparison group. Anal melanoma (AM) demonstrated the lowest survival rate at 2.5 per cent. Neuroendocrine tumors (NETs) demonstrated similar survival as SCC (10-year survival for regional disease of 25 and 22.3%, respectively). Ten-year survival of small cell NETs resembled AM (5.3 vs 2.5%). Age 60 years or older, sex, black race, stage, and surgery were independent predictors of survival. This study presents the largest patient series of rare anal neoplasms. NETs of the anal canal demonstrate similar survival patterns to SCC, whereas small cell NETs more closely resemble AM. Accurate histologic diagnosis is vital to determine treatment and surgical management because survival patterns can differ among rare anal neoplasms.

International Journal of Radiation Oncology Biology Physics, 2003

Primary adenocarcinoma of the anus is a rare tumor. The current standard treatment consists of abdominoperineal resection (APR). The aim of this Rare Cancer Network study was to evaluate the prognostic factors and outcome after the three most commonly used treatment approaches.This multicenter study collected data from 82 patients: 15 with T1 (18%), 34 with T2 (42%), 22 with T3 (27%), and 11 with T4 (13%) tumors according to the TNM classification (International Union Against Cancer, 1997). Patients were separated into, and analyzed according to, three treatment categories: radiotherapy/surgery (RT/S group, n = 45), combined radiochemotherapy (RT/CHT group, n = 31), and APR alone (APR group, n = 6). The main patient characteristics were evenly distributed among the three groups.The actuarial locoregional relapse rate at 5 years was 37%, 36%, and 20%, respectively, in the RT/S, RT/CHT, and APR groups (RT/S vs. RT/CHT, p = 0.93; RT/CH vs. APR, p = 0.78). The 3-, 5-, and 10-year overall survival rate was 47%, 29%, and 23% in the RT/S group, 75%, 58%, and 39% in the RT/CHT group, and 42%, 21%, and 21% in the APR group (RT/CHT vs. RT/S, p = 0.027), respectively. The 5- and 10-year disease-free survival rate was 25% and 18% in the RT/S group, 54% and 20% in the RT/CHT group, and 22% and 22% in the APR group (RT/CHT vs. RT/S, p = 0.038), respectively. Multivariate analysis revealed four independent prognostic factors for survival: T stage, N stage, histologic grade, and treatment modality.Primary adenocarcinoma of the anal canal requires rigorous management. Multivariate analysis showed that T and N stage, histologic grade, and treatment modality are independent prognostic factors for survival. We observed better survival rates after combined RT/CHT. We also recommend using APR only for salvage treatment.

ANZ Journal of Surgery, 2004

Through the 1970s patients presenting with anal canal carcinoma were managed with a surgical approach--abdomino-perineal resection. Since then, the pioneering work of Nigro et al. and a series of large clinical trials have clearly demonstrated that combined chemotherapy and radiotherapy result in greater local control, colostomy-free survival and increase in overall patient survival. The aim of the present study is to determine how widely the combined modality approach has been adopted in routine clinical practice and what outcomes are achieved in this setting. All patients with anal cancer treated at three tertiary referral centres over an 11-year period (1991-2001) were identified. Data were collected by a retrospective record review. Our search identified a total of 50 patients: 22 men and 28 women, with a median age of 62 years. Four patients had metastatic disease diagnosed at presentation. Nine patients (18%) were at least 75 years of age and three were known to be HIV positive. Median potential follow up is 52 months. Of the 46 patients treated for cure, 38 received a combination of chemotherapy and radiation, with 79% achieving a complete response. Efficacy was maintained in treated elderly patients (> or =75 years). The 5-year survival of the 38 patients with local or locoregional disease who received combined chemoradiation modality was 63%. Overall this series demonstrates that combined chemotherapy and radiotherapy has been adopted as standard treatment with outcome data similar to those reported in the randomized clinical trials. Where possible elderly patients should receive combined modality therapy.

Annals of Surgical Oncology, 2008

Background: Over the past two decades, recommended treatment for squamous cell carcinoma of the anal canal has shifted from surgery to primary chemoradiation. Resection is now reserved for persistent or recurrent disease. Our objectives were (1) to evaluate treatment trends over the past 20 years, (2) to assess contemporary treatment utilization, and (3) to examine the impact of recommended vs nonguideline treatment on survival.

Annals of Surgery, 1994

The outcomes of patients with squamous cell carcinoma of the anal canal treated by either sphincter-preserving procedures or radical surgery were evaluated, with the goals of identifying factors predicting treatment failure and quantifying results of salvage therapy in patients with recurrent disease.