Anal Cancer: The Past, Present and Future

Prognostic value of PD-L1 expression in patients with anal cancer: a meta-analysis

Background: The present meta-analysis was performed to evaluate the prognostic and clinicopathological significance of PD-L1 in anal cancer (AC). Methods: Hazard ratios (HRs) and 95% CIs regarding overall survival (OS) and progression-free survival (PFS) were calculated based on PD-L1 levels. Results: According to the combined data, PD-L1 showed no significant relationship with OS (HR = 0.76; 95% CI = 0.35-1.67; p = 0.502) or PFS (HR = 0.88; 95% CI = 0.35-2.33; p = 0.789) in patients with AC. Based on subgroup analysis, PD-L1 overexpression significantly predicted prolonged OS (HR = 0.38; 95% CI = 0.17-0.84; p = 0.017) in tumor node metastasis stages I-III and inferior PFS (HR = 2.73; 95% CI = 1.32-5.65; p = 0.007) in patients with stage I-IV AC. Conclusion: PD-L1 level assessed by immunohistochemistry did not significantly predict survival outcomes in AC cases.

Trends in epidemiology and primary treatment of anal squamous cell carcinoma in the Netherlands (1990-2021)

A rapid increase in the incidence of anal squamous cell carcinoma (SCC) was reported in several countries over the past decades. This study assessed trends in epidemiology and primary treatment over a 32-year period (1990-2021) using the Netherlands Cancer Registry. The study population included 4273 patients, 44.2% male and 55.8% female (median age 63 years). The age-standardised incidence rate (European Standardised Rate, ESR) increased from 0.5 to 1.6 per 100,000, which entailed an average annual percentage change (AAPC) of 5.0% (95% confidence interval [CI]: 4.5%-5.8%). While incidence among females increased continuously over the total period (AAPC 4.9%; 95%CI: 4.4%-5.6%), to 1.8 per 100,000 ESR in 2021, incidence among males increased until 2016 (annual percentage change [APC] of 6.3%; 95%CI: 5.6%-10.7%), after which it seemed to stabilise (APC -2.1%; 95%CI: -16.8%-4.5%). Significant trends were also observed in distribution of age, tumour stage and primary treatment modalities. Five-year relative survival (RS) was estimated using the Pohar-Perme estimator, and this improved from 56.1% in 1990-1997 (95%CI: 49.3%-62.4%) to 67.9% in 2014-2021 (95%CI: 64.7%-70.9%), but remained poor for stage IV disease. Evaluation through a multivariable Poisson regression model demonstrated diagnosis in the most recent period to be independently associated with better RS, in addition to female sex, younger age, early disease stage and any treatment. In conclusion, the rising incidence of anal SCC seems to decline in males, but not in females, and advances in diagnostics and therapeutic management have likely contributed to improved prognosis.

Human papillomavirus genotype distribution patterns in Zimbabwe; is the bivalent vaccine sufficient?

BACKGROUND

Vaccination against Human papillomavirus (HPV) is the primary preventative strategy that has been shown to reduce the burden of HPV related diseases. Zimbabwe introduced the bivalent vaccine (HPV 16/18) in the vaccination program targeting prepubescent girls in 2018. This review is an analysis of the distribution of HPV genotypes from various studies conducted in Zimbabwe to ascertain the effectiveness of the bivalent vaccine and make recommendations for future HPV vaccine choices.

SUMMARY

Zimbabwean studies have mostly reported on cervical HPV in the urban areas. The most frequent HPV genotypes from cervical sites were 16, 18, 33, 35, 45, 56 and 58. These were identified from samples with normal cytology, pre-cancer and invasive cervical cancer. The few studies that have been done in rural areas reported HPV 35 as the most frequent cervicovaginal genotype. From the anal region of individuals reporting for routine screening, HPV 16, 18, 35 52 and 58 were the most frequent. A study on genital warts identified HPV 6, 11, 16, 40, 51and 54. In a study on children with recurrent respiratory papillomatosis (RRP), HPV 6 and 11 were the most common and HPV 35 was also identified in these children. There is no available published data on HPV distribution in head and neck cancers in Zimbabwe.

KEY MESSAGES

Given that 83% of cervical cancers in Zimbabwe are caused by HPV 16/18, the bivalent vaccine could cover a significant proportion of HPV related cervical cancer. The current limitation of the bivalent vaccine is its failure to prevent benign lesions such as genital warts and RRP or all cervical cancer cases in Zimbabwe. For the prevention of most HPV related conditions, the nonavalent vaccine would be the most appropriate option for the Zimbabwean population. Currently there is no vaccine that includes HPV 35, yet this genotype was frequently identified in HPV related diseases. Vaccine developers may need to consider HPV 35 when manufacturing the next generation HPV vaccines. Furthermore, boys should also be included in HPV vaccination programs to improve herd immunity, as well as prevent RRP and HPV-related head and neck cancers.

Assessing Circulating Tumour DNA (ctDNA) as a Biomarker for Anal Cancer Management: A Systematic Review

This systematic review investigates the potential of circulating tumour DNA (ctDNA) as a predictive biomarker in the management and prognosis of squamous cell carcinoma of the anal canal (SCCA). PubMed, EMBASE, and Cochrane Central Registry of Controlled Trials were searched until 7 January 2024. Selection criteria included research articles exploring ctDNA in the context of anal cancer treatment response, recurrence risk assessment, and consideration of salvage surgery. A total of eight studies were therefore included in the final review, examining a total of 628 patients. These studies focused on three main themes: SCCA diagnosis and staging, treatment response, and patient outcomes. Significant heterogeneity was observed in terms of patient cohort, study methodology, and ctDNA biomarkers. Four studies provided information on the sensitivity of ctDNA biomarkers in SCCA, with a range of 82-100%. Seven studies noted a correlation between pre-treatment ctDNA levels and SCCA disease burden, suggesting that ctDNA could play a role as a biomarker for the staging of SCCA. Across all seven studies with paired pre- and post-treatment ctDNA samples, a trend was seen towards decreasing ctDNA levels post-treatment, with specific identification of a 'fast elimination' group who achieve undetectable ctDNA levels prior to the end of treatment and may be less likely to experience treatment failure. Residual ctDNA detection post-treatment was associated with poorer patient prognosis. This systematic review identifies the broad potential of ctDNA as a useful and decisive tool in the management of SCCA. Further analysis of ctDNA biomarkers that include larger patient cohorts is required in order to clearly evaluate their potential role in clinical decision-making processes.

A case of a rare type of cancer: Anal squamous cell carcinoma in a patient without significant risk factors

INTRODUCTION

Anal carcinoma is a relatively uncommon tumor that accounts for less than 2% of large bowel malignancies and approximately 1-6% of anorectal tumors. Most anal cancers originate in the mucosa between the anorectal junction and the anal verge. Risk factors for anal carcinoma include human papillomavirus (HPV), immunosuppression, older age, female gender, and smoking. Approximately 85% of anal cancers are squamous cell carcinoma, and the pathophysiology is believed to be linked to HPV-related inflammation, leading to dysplasia and progression to cancer.

CASE PRESENTATION

We present the case of a 65-year-old woman who sought medical attention at the emergency department (ED) due to rectal pain and concurrent rectal lesions persisting for the past three months. Before admission, she reported abdominal discomfort and constipation for 2-3 months, during which she took laxatives for relief. Laboratory findings in the ED were significant for anemia and leukocytosis, with all other values within normal limits. Blood tests, including antibodies for HPV and human immunodeficiency virus, were negative. A computed tomography scan of the abdomen and pelvis was largely unremarkable. On physical examination, perianal lesions with heaped-up edges were observed. A punch biopsy was subsequently performed, revealing squamous cell carcinoma (SCC). About three weeks following discharge, after one week of admission to the general medicine ward, the patient started chemoradiation therapy and reported some improvement in her symptoms. Seven weeks later, she was in remission.

DISCUSSION

Squamous cell carcinoma (SCC) of the anus, a rare disease entity, is often a slow and progressive malignancy. The length of time for patients to become symptomatic, in combination with its mimicking clinical presentation to common gastrointestinal tract diseases and its rarity, makes diagnosis challenging. Additionally, a patient lacking traditional risk factors for anal cancer, such as HPV and smoking, may further complicate diagnosis, treatment, and quality of life.

CONCLUSION

This case report emphasizes the pathogenesis and the similarities in clinical presentation of anal cancer to mild diseases, which may lead to a delay in diagnosis. Patients with anal carcinoma often delay seeking medical care, which is anecdotal in relation to the considerable overlap in symptoms of benign diseases such as hemorrhoids. Therefore, patients with "hemorrhoid" complaints, rectal bleeding, or rectal mass should warrant further physical examination and prompt referral to a gastroenterologist or a colorectal surgeon for additional evaluation.

The Role of Pentraxin 3 in Gastrointestinal Cancers

Gastrointestinal cancers have become a huge problem worldwide as the number of new cases continues to increase. Due to the growing need to explore new biomarkers and therapeutic targets for the detection and treatment of cancerous lesions, we sought to elucidate the role of Pentraxin-3 in the progression of cancerous lesions, as it is involved in the process of angiogenesis and inflammation. Statistically significant changes in the concentration of this parameter have emerged in many gastrointestinal cancer patients. Moreover, it is related to the advancement of cancer, as well as processes leading to the development of those changes. In the case of studies concerning tissue material, both increased and decreased tissue expression of the tested parameter were observed and were dependent on the type of cancer. In the case of cell lines, both human and animal, a significant increase in Pentraxin 3 gene expression was observed, which confirmed the changes observed at the protein level. In conclusion, it can be assumed that PTX3, both at the level of gene expression and protein concentrations, is highly useful in the detection of gastrointestinal cancers, and its use as a biomarker and/or therapeutic target may be useful in the future.

Immune-checkpoint inhibitors in anal squamous cell carcinoma: a systematic review and meta-analysis

INTRODUCTION

Squamous cell carcinoma of the anus (SCCA) is a rare tumor. While most patients with locally advanced disease are cured with chemo-radiotherapy, about a quarter eventually experience metastatic recurrence. Standard treatment for advanced disease is chemotherapy, but recently evidence on the activity of immunotherapy has been reported. We performed a systematic review and meta-analysis of prospective trials testing immune-checkpoint inhibitors (ICIs) in patients with SCCA.

OBJECTIVE

We aimed to evaluate the overall response rate (ORR) and the disease control rate (DCR) of ICIs in patients with advanced SCCA.

METHODS

We systematically searched PubMed, Embase, and Scopus, through December 31, 2022, for prospective trials assessing ICIs in patients with advanced SCCA. The primary and secondary endpoints were respectively ORR and DCR.

RESULTS

Six prospective trials were included in the analysis, one of which was randomized. Overall, seven treatment arms and 347 patients have been analyzed. Five treatment arms tested ICIs as monotherapy and two arms examined ICIs in combination with cetuximab and bevacizumab, respectively. The pooled ORR was 13% (95%CI, 10%-17%), with a DCR of 57% (95%CI, 40%-74%). Results did not change in a sensitivity analysis, which excluded the two treatment arms testing the combination of ICIs with other drugs.

CONCLUSIONS

The efficacy of ICIs in SCCAs is low. Combination strategies with targeted drugs or chemotherapy might represent a better therapeutic strategy for these patients. Further studies are awaited to identify resistance mechanisms to ICIs and optimize their efficacy.