A 2020 update of anal cancer: the increasing problem in women and expanding treatment landscape

Pathophysiology of Anal Cancer

The pathophysiology of the development of anal cancer is thought to be linked to chronic inflammation, a possible consequence of infections with human papillomavirus (HPV) or HIV, or inflammation from inflammatory bowel disease. Anal HPV-induced carcinogenesis bears similarities to its cervical counterpart via viral integration into the host genome and the development of precursor lesions termed anal intraepithelial neoplasia. HPV-16 and -18 are the most common HPV genotypes associated with anal cancer. Other risk factors for the development of anal cancer include chronic immunosuppression, sexual activity and sexually transmitted diseases, female gender, history of anogenital dysplasia, and smoking.

Anal high-grade intraepithelial neoplasia and cancer in women with HIV and women without HIV with other risk factors

OBJECTIVE

To determine the prevalence and the risk factors for anal high-grade intraepithelial neoplasia and anal cancer (HSIL+) in women with HIV (WWH), and to compare them to women without HIV with other risk factors.

DESIGN

Prospective cohort study.

METHODS

WWH and women without HIV with other risk factors were included. Screening for anal HSIL+ using anal cytology and HPV testing was performed. A high-resolution anoscopy with directed biopsy was also performed in patients with an abnormal cytology result or a positive HPV testing for high-risk (HR) genotypes, and in those with anal symptoms.

RESULTS

The period prevalence of anal HR-HPV infection and histological HSIL was 57.9% and 10.9% among WWH, and 60.8% and 9.2% among women without HIV. The prevalence of anal HPV 18 infection was higher in WWH. The risk factors for anal HSIL+ in WWH included anal HPV 16, other HR genotypes and low-risk genotypes infection, as well as a history of vulvar HSIL+. In women without HIV, the risk factors included anal HPV 16 infection, history of anogenital warts and of vulvar HSIL+, and immunosuppressive treatment.

CONCLUSIONS

A high prevalence of anal HPV infection and HSIL was observed in WWH and women without HIV with other risk factors. Both groups share anal HPV 16 infection and history of vulvar HSIL+ as risk factors for the development of anal HSIL+. Genotyping for anal HPV 16 may help identify women at higher risk of anal cancer.

Anal Cancer: The Past, Present and Future

Anal cancer is a rare cancer that accounts for about 2% of all gastrointestinal tract malignancies. Among anal cancer, squamous cell cancer is the most common malignancy. The incidence of all stages of anal squamous cell cancer has been increasing. Human papillomavirus infection and immunosuppression are major risk factors for anal cancer. The management of anal cancer has evolved over the past several decades and continues to do so. Chemoradiation therapy remains the mainstay for treatment for most patients with early-stage disease, whereas systemic therapy is the primary treatment for patients with metastatic disease. Patients with persistent disease or recurrence following chemoradiation therapy are treated with salvage surgery. Access to novel cytotoxic combinations and immunotherapy has improved the outcomes of patients with advanced disease. This review provides an overview of advances in the management of anal cancer over the past two decades. This paper reviews the epidemiology, risk factors, pathology, diagnosis, and management of localized and advanced anal squamous cell cancer, highlights current knowledge gaps in the management of anal cancer, and discusses future directions.

Natural History of Anal HPV Infection in Women Treated for Cervical Intraepithelial Neoplasia

Women with high-grade squamous intraepithelial lesions/cervical intraepithelial neoplasia (HSIL/CIN) are at high risk of anal human papillomavirus HPV infection, and it has also been suggested that self-inoculation of the virus from the anal canal to the cervix could explain HPV recurrence in the cervix after treatment of HSIL/CIN. We aimed to evaluate the bidirectional interactions of HPV infection between these two anatomical sites. We evaluated 68 immunocompetent women undergoing excisional treatment for HSIL/CIN. Immediately before treatment, samples from the anus and the cervix were obtained (baseline anal and cervical HPV status). Cervical HPV clearance after treatment was defined as treatment success. The first follow-up control was scheduled 4-6 months after treatment for cervical and anal samples. High resolution anoscopy (HRA) was performed on patients with persistent anal HPV infections or abnormal anal cytology in the first control. Baseline anal HPV was positive in 42/68 (61.8%) of the women. Anal HPV infection persisted after treatment in 29/68 (42.6%) of the women. One-third of these women (10/29; 34.5%) had HSIL/anal intraepithelial neoplasia (AIN). Among women achieving treatment success, cervical HPV in the first control was positive in 34.6% and 17.6% of the patients with positive and negative baseline anal HPV infection, respectively (p = 0.306). In conclusion, patients with persisting anal HPV after HSIL/CIN treatment are at high risk of HSIL/AIN, suggesting that these women would benefit from anal exploration. The study also suggests that women with anal HPV infection treated for HSIL/CIN might be at higher risk of recurrent cervical HPV even after successful treatment.

Carcinogenesis and Cancer Progression in De Novo Anal Squamous Cell Carcinoma After Organ Transplantation: A Systematic Review

Our aim was to perform a comprehensive literature review on the pathogenesis of squamous anal cancerin patients after solid-organ transplant. Medical databases were consulted until June 1, 2020, for potentially relevant publications.All studies on pathogenesis of de novo anal squamous cell carcinoma in solid-organ transplant recipients were included. Two researchers independently performed study selection, quality assessment, and data extraction and analysis. Twenty-one studies were included.None ofthe selected papers had been solely focused on carcinogenesis. Most ofthe studies identified human papillomavirus infection and immunosuppression to be significantly correlated with the development of de novo anal cancer in adult solid organ transplant recipients. CD4+ T-cell depletion and inactivation oftumor suppressor pathways were mainly implicated. All solid-organ transplant recipients, especially those who were human papillomavirus positive, were shown to be at increased risk for the development of posttransplant anal cancer. Further studies are needed to determine the specific mechanisms of pathogenesis according to different solid-organ transplant populations.

Volumetric Modulated Arc Therapy Improves Outcomes in Definitive Radiochemotherapy for Anal Cancer Whilst Reducing Acute Toxicities and Increasing Treatment Compliance

Simple Summary

Intensity-modulated radiotherapy (IMRT) is the standard of care in definitive chemoradiotherapy (CRT) for anal cancer. Only a limited number of studies have analyzed the clinical results with VMAT (volumetric modulated arc therapy, the advanced form of IMRT). We conducted a retrospective study on patients treated at our institution. We compared the outcomes of VMAT-treated and 3DCRT (3D conformal radiotherapy)-treated patients. VMAT reduced acute toxicities (i.e., primarily dermatitis and enteritis) to a great extent. Additionally, VMAT relevantly improved treatment compliance (i.e., less CRT interruptions/delays, shorter overall treatment time, and higher absolute 5-fluorouracil dose applied). Finally, we found improved cancer-specific survival and distant control in VMAT-treated patients. The present study underlines the great progress that has been achieved with IMRT/VMAT in the CRT of anal cancer. Our study is the first to demonstrate an improvement in treatment compliance and outcomes with VMAT. Future studies could address whether VMAT is advantageous when compared to conventional IMRT.

Abstract

Background: Intensity-modulated radiotherapy (IMRT) is the standard of care in chemoradiotherapy (CRT) for anal cancer. Until now, only a limited number of studies have analyzed the results with VMAT (volumetric modulated arc therapy). We conducted a retrospective study on patients treated at our institution. Patients and Methods: We included patients who received curative CRT for anal cancer. We compared VMAT-treated and 3DCRT (3D conformal radiotherapy)-treated patients. We analyzed toxicities (acute: CTCAE criteria; late: LENT/SOMA criteria), treatment compliance, overall survival, cancer-specific survival (CSS), distant control (DC), and locoregional control. Results: A total of 149 patients (3DCRT: n = 87, VMAT: n = 62) were included. The median follow-up was longer in 3DCRT-treated patients (3DCRT: 61.3 months; VMAT: 39.1 months; p < 0.05). VMAT-treated patients had more G3 tumors (3DCRT: 12/87 (13.8%); VMAT: 18/62 (29.0%), p < 0.001). VMAT reduced acute toxicities ≥grade 3 (3DCRT: n = 48/87 (55.2%); VMAT: n = 11/62 (17.7%), p < 0.001). VMAT improved treatment compliance (less interruptions/delays) (3DCRT: 37/87, 42.5%; VMAT: 4/62, 6.5%; p < 0.001), provided a shorter median overall treatment time (3DCRT: 41 days; VMAT: 38 days; p = 0.02), and gave a higher median absolute 5-fluorouracil dose (3DCRT: 13,700 mg; VMAT: 14,400 mg; p = 0.001). Finally, we found improved CSS (p = 0.02; 3DCRT: 81.9% at 3 years; VMAT: 94.1% at 3 years) and DC (p = 0.01; 3DCRT: 89.4% at 3 years; VMAT: 100.0% at 3 years) with VMAT. Summary: Our study is the first to demonstrate improved treatment compliance and outcomes with VMAT for anal cancer. Previous studies have indicated that organs at risk sparing might be more improved with the use of VMAT vs. with conventional IMRT. Future studies should address whether these advantages lead to a further reduction in CRT-associated morbidity.