SU-E-T-69: A Radiobiological Investigation of Dose Escalation in Lower Oesophageal Tumours with a Focus On Gastric Toxicity

Journal Article · Mon Jun 15 04:00:00 EDT 2015 · Medical Physics

DOI:https://doi.org/10.1118/1.4924430· OSTI ID:22545199

Carrington, R ^[1]; Staffurth, J; Spezi, E; Crosby, T ^[2]; Warren, S; Partridge, M; Hawkins, M ^[3]; Gwynne, S ^[4]

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1. Cardiff University, Cardiff, Wales (United Kingdom)
2. Velindre Cancer Centre, Cardiff, Wales (United Kingdom)
3. CRUK/MRC Oxford Institute for Radiation Oncology, Oxford (United Kingdom)
4. Singleton Hospital, Swansea, Wales (United Kingdom)

The incidence of lower third oesophageal tumours is increasing in most Western populations. With the role of radiotherapy dose escalation being identified as a research priority in improving outcomes, it is important to quantify the increased toxicity that this may pose to sites such as the lower oesophagus. This study therefore aims to investigate the feasibility of lower oesophageal dose escalation with a focus on stomach tissue toxicity.The original 3D-conformal plans (50Gy3D) from 10 patients in the SCOPE1 trial were reviewed and compared to two RapidArc plans created retrospectively to represent the treatment arms of the forthcoming SCOPE2 trial: 50GyRA and 60GyRA (50Gy to PTV1 with a simultaneously integrated boost of 60Gy to PTV2). The stomach was contoured as stomach wall and dose constraints set according to QUANTEC. Normal tissue complication probability (NTCP) was estimated for the stomach wall for an endpoint of gastric bleeding. There was a mean increase of 5.93% in NTCP from 50Gy3D to 60GyRA and a mean increase of 8.15% in NTCP from the 50GyRA to 60GyRA. With NTCP modelling restricted to volumes outside PTV2, there was a mean decrease of 0.92% in NTCP from the 50Gy3D to 60GyRA, and a mean increase of 2.25% from 50GyRA to 60GyRA. There was a strong correlation between the NTCP and Stomach Wall/PTV1 overlap volume for all plans (R=0.80, 0.77 and 0.77 for 60GyRA, 50GyRA and 50Gy3D respectively). There was also a strong correlation between NTCP and the Stomach Wall/PTV2 overlap volume for 60GyRA (R= 0.82).Radiobiological modelling suggests that increasing the prescribed dose to 60Gy may be associated with a significantly increased risk of toxicity to the stomach within the boost volume. It is recommended that stomach toxicity be closely monitored prospectively when treating patients with lower oesophageal tumours in the forthcoming SCOPE 2 trial. Rhys Carrington received a PhD studentship grant from Cancer Research Wales. Grant number: 2445; Dr Warren and Dr Partridge are supported by Cancer Research UK. Grant number: C5255/A15935. Dr Hawkins is supported by MRC grant MC-PC-12001/2.

• OSTI ID: 22545199
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 6 Vol. 42; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
61 RADIATION PROTECTION AND DOSIMETRY
ANIMAL TISSUES
CORRELATIONS
DOSIMETRY
ESOPHAGUS
LIMITING VALUES
NEOPLASMS
PATIENTS
RADIATION DOSES
RADIOTHERAPY
REVIEWS
SIMULATION
STOMACH
TOXICITY