Intensified intensity-modulated radiotherapy in anal cancer with prevalent HPV p16 positivity

Prognostic value of high-risk human papillomavirus DNA and p16INK4a immunohistochemistry in patients with anal cancer: An individual patient data meta-analysis

BACKGROUND

High-risk human papillomavirus (hrHPV) types represent the aetiological agents in a major proportion of anal squamous cell carcinomas (ASCC). Several studies have suggested a prognostic relevance of HPV-related markers, particularly hrHPV DNA and p16^INK4a (p16) protein expression, in patients with ASCC. However, broader evaluation of these prognostic marker candidates has been hampered by small cohort sizes and heterogeneous survival data among the individual studies. We conducted an individual patient data (IPD) meta-analysis to determine the prognostic value of hrHPV DNA and p16 in patients with ASCC while controlling for major clinical and tumour covariates.

PATIENTS AND METHODS

A systematic literature search was conducted to identify all published studies analysing p16 alone or in combination with hrHPV DNA and reporting survival data in patients with ASCC. Clinical and tumour-related IPD were requested from authors of potentially eligible studies. Survival analyses were performed with a proportional hazard Cox model stratified by study and adjusted for relevant covariates. The study-specific hazard ratios (HRs) for the exposures were pooled using a random-effects model. Kaplan-Meier curves from different studies were pooled per exposure group and weighted by the study's total sample size.

RESULTS

Seven studies providing IPD from 693 patients with ASCC could be included in the meta-analysis. Seventy-six percent of patients were p16+/hrHPV DNA+, whereas 11% were negative for both markers. A discordant marker status was observed in 13% of cases. Patients with p16+/hrHPV DNA+ ASCC showed significantly superior overall survival (OS) compared with patients with p16-/hrHPV DNA- tumours (pooled adjusted HR = 0.26 [95% confidence interval {CI}, 0.14-0.50]) with pooled three-year OS rates of 86% (95% CI, 82-90%) versus 39% (95% CI, 24-54%). Patients with discordant p16 and hrHPV DNA status showed intermediate three-year OS rates (75% [95% CI, 56-86%] for p16+/hrHPV DNA- and 55% [95% CI, 35-71%] for p16-/hrHPV DNA+ ASCC).

CONCLUSION

This first IPD meta-analysis controlling for confounding variables shows that patients with p16+/hrHPV DNA+ ASCC have a significantly better survival than patients with p16-/hrHPV DNA- tumours.

Evolution of the Role of Radiotherapy for Anal Cancer

Prior to the 1980s, the primary management of localized anal cancer was surgical resection. Dr. Norman Nigro and colleagues introduced neoadjuvant chemoradiotherapy prior to abdominoperineal resection. Chemoradiotherapy 5-fluorouracil and mitomycin C afforded patients complete pathologic response and obviated the need for upfront surgery. More recent studies have attempted to alter or exclude chemotherapy used in the Nigro regimen to mitigate toxicity, often with worse outcomes. Reductions in acute adverse effects have been associated with marked advancements in radiotherapy delivery using intensity-modulated radiation therapy (IMRT) and image-guidance radiation delivery, resulting in increased tolerance to greater radiation doses. Ongoing trials are attempting to improve IMRT-based treatment of locally advanced disease with efforts to increase personalized treatment. Studies are also examining the role of newer treatment modalities such as proton therapy in treating anal cancer. Here we review the evolution of radiotherapy for anal cancer and describe recent advances. We also elaborate on radiotherapy's role in locally persistent or recurrent anal cancer.

Reirradiation of pulmonary artery intimal sarcoma: A case report

We report here the case of a patient with 4 years long-term survival after treatment with surgery, chemotherapy, and radiotherapy with good local control. This case highlights the possible role of radiation therapy in this tumor.

[Anal canal cancer: In the era of intensity-modulated radiotherapy, outstanding issues]

Intensity-modulated radiotherapy makes possible to optimize the irradiation and spare normal tissues. The toxicity remains important with concomitant chemotherapy often associated. The improvement of MRI and PET-CT define more precisely the target volumes, which need a higher dose, but necessitates to respect the rules of contouring. The treatment is uniform whatever the stage but should be individualized based on clinical stage and tumor response. New paradigms concern biology, staging, volumes and doses, fractionation and combined treatments.

Management of locally advanced anal canal carcinoma with intensity-modulated radiotherapy and concurrent chemotherapy

The best curative option for locally advanced (stages II-III) squamous-cell carcinomas of the anal canal (SCCAC) is concurrent chemo-radiotherapy delivering 36-45 Gy to the prophylactic planning target volume with an additional boost of 14-20 Gy to the gross tumor volume with or without a gap-period between these two sequences. Although 3-dimensional conformal radiotherapy led to suboptimal tumor coverage because of field junctions, this modality remains a standard of care. Recently, intensity-modulated radiotherapy (IMRT) techniques improved tumor coverage while decreasing doses delivered to organs at risk. Sparing healthy tissues results in fewer severe acute toxicities. Consequently, IMRT could potentially avoid a gap-period that may increase the risk of local failure. Furthermore, these modalities reduce severe late toxicities of the gastrointestinal tract as well as better functional conservation of anorectal sphincter. This report aims to critically review contemporary trends in the management of locally advanced SCCAC using IMRT and concurrent chemotherapy.

Evolution and Management of Treatment-Related Toxicity in Anal Cancer

Over the past several decades, clinical trials have demonstrated improved disease-related outcomes in the definitive treatment of anal cancer. Although treatment with radiation and concurrent chemotherapy results in high rates of cure, significant acute and late toxicities are seen. This review focuses on the evolution of treatment-related toxicity for anal cancer. Management of these adverse effects is reviewed, as are future directions in anal cancer treatment and their impact on toxicity.

Anal squamous cell carcinoma - State of the art management and future perspectives

Anal squamous cell carcinoma (ASCC) is associated with infection with high-risk strains of human papilloma virus (HPV) in 70-90% of cases and a rise in incidence has been observed in the last decades. Definitive chemoradiotherapy (CRT) using 5-fluorouracil and mitomycin C constitutes the standard treatment for localized disease, but about 30% of patients do not respond or relapse locally. Phase I/II trials testing targeted agents, such as epidermal-growth-factor receptor (EGFR) inhibitors, have failed to improve clinical outcome and resulted in increased toxicities. Modern imaging methods and biomarkers, also in the context of HPV status, should be further explored to improve patient stratification. In the present review, we will discuss the current clinical evidence and future perspectives in the management of ASCC. HPV-positive ASCC is more immunogenic with a higher density of tumor infiltrating lymphocytes that correlate with better response to CRT and more favorable prognosis compared to HPV-negative tumors. Immunotherapies including immune checkpoint inhibitors have brought new hope and promising results were recently demonstrated in metastatic ASCC. The addition of immunotherapies to CRT for localized disease is tested in early phase trials, and these results could have a profound impact on the way we treat ASCC in near future. Further research and novel approaches are expected to enhance our understanding of tumor biology and immunology, and improve patient stratification and treatment adaptation in the context of personalized medicine.

Hematologic toxicity in anal cancer patients during combined chemo-radiation: a radiation oncologist perspective

INTRODUCTION

Hematologic toxicity is an important side effect occurring in patients affected with anal cancer, undergoing combined radio-chemotherapy, with consistent clinical meaningfulness. Areas covered: Since more than a half of bone marrow is comprised within the pelvic region, the radiation dose received by this functional compartment is crucial. Modern imaging modalities may provide a useful tool to identify bone marrow and new delivery technology may enhance the radiation oncologist's possibility to selectively spare these structures, potentially decreasing acute hematologic toxicity profile in this setting. Expert commentary: Correlation between dose to pelvic structures and acute hematologic toxicity has been studied in several oncological settings, mainly on a retrospective frame. Different dose metrics were found to be correlated including mean doses and different points within the dose-volume histogram ranging from low to medium-high doses. Several imaging modalities were used to identify bone marrow both morphological and functional. Several clinical endpoints were used. In general, accounting for bone marrow during the treatment planning process may be important to decrease the acute hematologic toxicity profile during concurrent chemo-radiation in anal cancer patients. The most appropriate strategy to address this issue need further investigation and deserve validation in a prospective clinical framework.

Quantifying target-specific motion in anal cancer patients treated with intensity modulated radiotherapy (IMRT)

Background and purpose

Intensity modulated radiotherapy requires all target areas to be treated by a single radiotherapy plan. In anal cancer, the pelvic nodes, inguinal nodes and primary tumour represent three different targets. We aim to calculate target-specific motion in anal cancer radiotherapy, when delivered using a single pelvic online auto-match.

Materials and methods

Twenty consecutive patients treated using IMRT at a single institution were studied. CBCTs were retrospectively re-matched around the inguinal nodes and primary tumour. Match values were recorded relative to origin, defined as pelvic CBCT auto-match. Systematic and random errors were quantified to determine target-specific motion and suggested margins calculated using van Herk formulae.

Results

The suggested margins to cover the independent motion of the inguinal and anal targets for LR, CC and AP set up around the inguinal nodes were 1.5 mm, 2.7 mm and 2.8 mm; and the primary tumour were, 4.6 mm, 8.9 mm and 5.2 mm respectively.

Conclusions

Target-specific set up will likely result in reduced treatment volumes and as such reduced toxicity. This is the first time a relationship has been described between pelvic bones, inguinal nodes and primary tumour. The PLATO study will prospectively assess the toxicity and outcomes of this target-specific margins strategy.