Surgical considerations in anal cancer

Research on Anal Squamous Cell Carcinoma: Systemic Therapy Strategies for Anal Cancer

Simple Summary

Anal cancer is rare with an estimated 9000 new cases predicted to occur in the United States in 2021. However, rates of new anal cancer cases and deaths from the disease are increasing by about 2% and 3% per year respectively. In light of these trends it is critical to better understand the nature of this disease and progress in its management. The present review focuses on the history and development of the role of systemic therapy in the treatment of anal cancer. Major trials establishing the role of chemotherapy in the management of locoregional and metastatic anal cancer are summarized. In addition, the rapidly evolving role of immunotherapy is discussed. Finally, major insights into the molecular pathobiology of anal cancer and opportunities for advancement in precision medicine in treatment of the disease.

Abstract

Anal squamous cell carcinoma (ASCC) is a rare malignancy, with most cases associated with human papilloma virus and an increased incidence in immunocompromised patients. Progress in management of ASCC has been limited not only due to its rarity, but also the associated lack of research funding and social stigma. Historically, standard of care for invasive ASCC has been highly morbid surgical resection, requiring a permanent colostomy. Surgery was associated with disease recurrence in approximately half of the patients. However, the use of chemotherapy (5-fluorouracil and mitomycin C) concomitantly with radiation in the 1970s resulted in disease regression, curing a subset of patients and sparing them from morbid surgery. Validation of the use of systemic therapy in prospective trials was not achieved until approximately 20 years later. In this review, advancements and shortcomings in the use of systemic therapy in the management of ASCC will be discussed. Not only will standard-of-care systemic therapies for locoregional and metastatic disease be reviewed, but the evolving role of novel treatment strategies such as immune checkpoint inhibitors, HPV-based vaccines, and molecularly targeted therapies will also be covered. While advances in ASCC treatment have remained largely incremental, with increased biological insight, an increasing number of promising systemic treatment modalities are being explored.

Premalignant and Malignant Perianal Lesions

Anal cancer is a heterogeneous and rare disease process that accounts for ∼1.5% of all gastrointestinal tract malignancies. The perianal skin plays host to a variety of different premalignant and malignant lesions, all with variable histology, treatment options, and prognosis. Anal cancers in general are notorious for having a delayed or missed diagnosis leading to treatment delays and may have an impact on survival. This delay is in part due to the nonspecific symptomatology and also improper physical examination of the sensitive and anatomically complex perianal region and anal canal. This article examines the various types of perianal cancers and their precursor lesions and will explore treatment options as well as outcomes and prognosis.

Locally Recurrent Disease Related to Anal Canal Cancers

Surgery for anal cancer is usually reserved for patients with persistent disease or local recurrence after definitive chemoradiation therapy. Patients with local recurrence should be re-evaluated for evidence of metastatic disease using positron emission tomography-computed tomography, and the local anatomy should be delineated with MRI. Eligible patients should undergo tailored surgery with the aim of achieving an R0 resection. Management is best undertaken within a specialized multidisciplinary setting. Careful patient selection and shared decision making are paramount for achieving acceptable patient-centered outcomes.

Squamous cell carcinoma of the anal canal: a review of the aetiology, presentation, staging, prognosis and methods available for treatment

Anal cancer is an uncommon malignancy, with the majority of cases comprised of squamous cell carcinomas. The increasing incidence of this disease reflects a rise in the transmission of the human papillomavirus, the causative organism of most tumours. Abdominoperineal resection (APR), once the primary mode of treatment, has been supplanted by sphincter-saving combination chemoradiation as the first-line therapy. However, surgeons continue to play a role in the multidisciplinary management of patients with anal cancer for diagnosis and post-treatment surveillance. Sentinel node biopsy may identify patients with clinically and radiographically negative inguinal lymph nodes who will benefit from groin irradiation. In very select cases, the controversial means of local excision has been employed as primary treatment, often in conjunction with radiation and chemotherapy. The management of persistent or recurrent anal cancers following primary chemoradiation remains a concern, for which only salvage APR currently offers the possibility of a cure. The introduction of human papillomavirus vaccines presents the exciting potential for the eradication of the disease.

Premalignant neoplasms and squamous cell carcinoma of the anal margin

Premalignant and malignant lesions of the anal margin are rare. Understanding anal anatomy and performing a biopsy of any suspicious lesions are essential in avoiding a delay in diagnosis and appropriately treating these tumors. Wide local excision continues to remain the treatment of choice for many of these lesions. Combined multimodality treatment has come to play an important role in managing patient with more advanced or metastatic disease.

Anal neoplasms

A variety of lesions comprise tumors of the anal canal, with carcinoma in situ and epidermoid cancers being the most common. Less common anal neoplasms include adenocarcinoma, melanoma, gastrointestinal stromal cell tumors, neuroendocrine tumors, and Buschke-Lowenstein tumors. Treatment strategies are based on anatomic location and histopathology. In this article different tumors and management of each, including a brief review of local excision for rectal cancer, are discussed in turn.

Anal intraepithelial neoplasia and anal cancer in dermatological practice

Anal intraepithelial neoplasia is considered to be a precursor lesion of invasive anal cancer. It is now increasingly recognized in high-risk groups, such as men who have sex with men and HIV-infected patients. Human papillomaviruses are considered to be an important aetiological agent in both anal intraepithelial neoplasia and anal cancer. Dermatologists are likely to encounter these conditions among the differential diagnoses to be considered in high-risk patients presenting with perianal and anal lesions. Anal cancer rates are also increasing among the HIV-infected and HIV-non-infected population. The successful treatment of anal intraepithelial neoplasia may reduce the risk of subsequent development of anal cancer. However, current therapies for anal intraepithelial neoplasia may be associated with treatment-related morbidity and are not well validated. It is currently not proven that they reduce the likelihood of the development of anal cancer. Nevertheless, screening for anal intraepithelial neoplasia is being advocated for high-risk groups and may become standard dermatological care for these patients. In view of recent developments in the understanding of this condition, this article reviews the current understanding of anal intraepithelial neoplasia and its treatment from a dermatological perspective.

Avaliação dos resultados do tratamento de 14 doentes de carcinoma espinocelular anal

A radioquimioterapia (RT/QT) tornou-se o tratamento de escolha para o carcinoma espinocelular anal (CEC). Na recidiva local ou na persistência da doença, deve-se instituir o tratamento cirúrgico. OBJETIVO: O objetivo deste estudo retrospectivo foi analisar os resultados do tratamento de doentes de CEC anal. MÉTODO: Acompanhamos 17 pacientes com diagnóstico anátomo-patológico de carcinoma espinocelular anal. Eram 14 (82,3%) do sexo feminino e três (17,8%) do masculino. A idade variou de 36 a 78 anos, com média de idade de 59,1 anos. Utilizando a classificação TNM, tivemos quatro (23,6%) no estádio I, seis (35,2%) no II, quatro (23,6%) no IIIa e três (17,6%) no IIIb. Todos foram submetidos a tratamento inicial com RT/QT, exceto um submetido a ressecção local. Definimos que a biópsia negativa, realizada entre 12 e 16 semanas após esse tratamento, determinaria o controle local da doença. RESULTADOS: Perdemos seguimento de três doentes (17,6%). Seguimos os 14 restantes (82,3%) entre um e cinco anos. Todos os doentes nos estádios I e II (10) apresentaram regressão total da doença, enquanto que três (75%) nos estádios IIIa e IIIb tiveram remissão completa. Realizamos a amputação abdomino-perineal de resgate em dois doentes e ressecção local em outros dois. A recidiva local ocorreu em dois (20%) nos estádios I e II e em dois (75%) nos estádios mais avançados (IIIa e IIIb). A sobrevivência em 3 anos foi de 100% nos que se encontravam nos estádios I e II, embora o controle da doença fosse atingido em oito (80%). Nos quatro doentes que estavam nos estádios IIIa e IIIb, a sobrevivência em um ano foi de 75% e em três anos foi de 25%. Esse último permanece livre da doença. Complicações do tratamento radioterápico ocorreram em oito doentes (57,1%). Nenhum óbito foi constatado durante o tratamento RT/QT. Os dois doentes, (14,3%) com sorologia positiva para HIV, apresentavam infecção anal pelo Papilomavírus humano (HPV). CONCLUSÃO: A análise dos nossos resultados evidenciou que o esquema de tratamento empregado foi efetivo para o controle local e preservação da função esfincteriana do ânus e que, na falha do tratamento radioquimioterápico, a operação de resgate controlou localmente a doença.