Compliance to chemoradiation in squamous cell carcinoma of the anus

The randomized controlled trial (RCT) remains the preferred design to determine effectiveness of a novel intervention in patients with cancer. The accepted method of primary analysis of phase III trials of radical chemoradiotherapy is by intention to treat (ITT). Yet, investigators often resort to 'post hoc' analyses comparing only patients who received the treatment per protocol (PP). Analysis of treatment PP aims to maintain the comparable groups achieved by randomisation, whilst identifying a true or more accurate treatment effect if the planned chemoradiotherapy is optimally applied with full compliance. Poor compliance is recognised to be associated with inferior outcomes. Reasons for poor compliance if identified and understood, might influence the design of future trials. Yet this entire methodology risks substantial bias and is often disparaged. In localised squamous cell carcinoma of the anus (SCCA) chemoradiotherapy with concurrent 5-flurouracil (or capecitabine) and mitomycin C achieves high rates of local control, but results in substantial acute toxicities. Some novel radiotherapy techniques (intensity modulated radiotherapy (IMRT), meticulous organs-at-risk (OAR) contouring, and techniques such as sparing of PET-active bone marrow) appear to reduce acute toxicity. Good quality assurance in the design of trials, patient education, optimizing nutrition, proactive surveillance during treatment, and early interventions might also improve compliance. This review examines the recently published findings on compliance in the ACT II trial and data from other studies using chemoradiotherapy in SCCA to explore compliance.