Anal cancer: radiotherapy and imaging biomarkers

Background: Anal squamous cell carcinoma (ASCC) is an uncommon but increasing malignancy. Standard treatment is definitive chemo-radiotherapy, but controversy remains regarding the optimal radiotherapy dose, the role of positron emission tomography (PET), and the management of early disease. Methods: In section one, a patterns of care survey of Australian clinicians explores the current management of early ASCC, and a modelling study reviews the impact of contour variation on tumour control probability when using intensity modulated radiotherapy (IMRT). In section two, a systematic review and meta-analysis explores the role of PET in ASCC, and a clinical trial investigates the use of PET for response assessment. Section three focuses on a prospective clinical trial assessing multi-parametric magnetic resonance imaging (MP-MRI) as a biomarker for ASCC. Results: Respectively, the findings can be summarised as follows: 1) considerable variation in the management of early ASCC indicates the need for guidelines and standardisation, 2) when using IMRT, minor contour variations likely have little impact on tumour control when clinicians follow contouring guidelines, 3) PET has a significant impact on staging and radiotherapy planning and appears to be useful for response assessment, and 4) MP-MRI is a potential biomarker for ASCC. Conclusion: These publications contribute to the current treatment of ASCC and identify imaging biomarkers that may become an important component of future management.