An evidence-based UK IMRT solution for anal cancer: the development of the control arm for future UK led clinical trials.


Year:

Session type:

Rebecca Muirhead1, Richard A Adams2, Duncan C Gilbert3, Mark Harrison4, Robert Glynne-Jones4, David Sebag-Montefiore5, Maria A Hawkins1
1The Gray Institute for Radiation Oncology & Biology, Oxford, UK, 2School of Medicine, Cardiff University, Cardiff, UK, 3Sussex Cancer Centre, Royal Sussex County Hospital, Brighton, UK, 4Mount Vernon Hospital, Northwood, UK, 5University of Leeds, St James Institute of Oncology, Leeds, UK

Background

Chemoradiation (CRT) is standard treatment for anal cancer achieving loco-regional control and preservation of anal function without a colostomy. Previous phase III trials including ACT2 used relatively crude radiotherapy techniques that cause acute and late radiation morbidity and may contribute to treatment failure due to treatment breaks [1]. An evidence-based IMRT solution is required toform the control arm for future UK anal cancer trials that can test the benefit from dose-escalation to the gross tumour and areas of nodal spread.

Method

We conducted a systematic PubMed/MEDLINE and Embase database search of Anal Cancer IMRT full articles and abstracts published since 2005. Dose fractionation to the gross tumour volume and nodes and elective nodal irradiation were reviewed and compared with the previous ACT2 technique.

Results

Representatives from six centres reviewed the results and held three face to face meetings. A single phase IMRT approach is recommended performed in the supine position with I.V. contrast. Radiobiological modelling was used to derive a continuous single phase solution similar to the approach used in ACT 2. Recommended gross tumour volumes doses to the primary are 50.4Gy in 28 fractions (F) for T1/2 and 53.2Gy in 28GF to T3/4N+ disease. The elective nodal irradiation dose is 40Gy in 28 fractions. Planning objectives and constraints are similar to those used by the RTOG 0529 phase II study [2]. A further five centres reviewed the draft protocol leading to minor modifications.

Conclusion

We present an evidence-based UK Anal IMRT consensus protocol that is suitable for use as the control arm of future UK led anal cancer trials and routine clinical practice.