Lisa Durrant

Modeling early haematologic adverse events in conformal and intensity-modulated pelvic radiotherapy in anal cancer.

Background and purpose To determine if there are differences between dose to pelvic bone marrow (PBM) using intensity modulated radiotherapy (IMRT) under UK guidance versus conformal radiotherapy (CRT) per ACT II protocol and if differences translate to rates of early haematological adverse events grade 3 or greater (HT3+). Methods and materials Two groups of 20+ patients, treated under IMRT and CRT regimes respectively, were identified. All patients underwent weekly blood cell count: haemoglobin (HgB), white cell count (WCC), absolute neutrophil count (ANC) and platelets (plats). Percent volume of PBM and sub structures receiving 5–25 Gy were tested for statistical significance. Regression models were used to test for correlation to blood counts. NTCP modeling was also performed. Results PMB dose metrics showed a significant increase in the IMRT group. Regression analysis showed iliac and lumbosacral PBM dose metrics to associate with reduced nadir ANC and WCC. NTCP at HT3+ was 0.13 using IMRT relative to 0.07 using CRT (p < 0.05). Conclusion Whilst this is a relatively small retrospective study and lacks information on the distribution of active PBM, IMRT treatment has been shown to significantly increase PMB irradiation. PBM dose metrics have been shown to be predictive of WCC and ANC suppression. NTCP modeling predicts much high risk of HT3+. Paradoxically, actual rates of HT3+ were comparable suggesting that differences in the distributions of dose metrics maybe a significant factor and/or that there are insufficiency in the NTCP modeling.

Health service provision and the use of pressure-redistributing devices: mixed methods study of community dwelling individuals with pressure injuries

Background: Health care within the home setting is a vital and growing component of pressure injury (PI) prevention and management. Objectives: To describe the use of health services and pressure-redistributing devices in community dwelling patients with PI’s. Design: Mixed-methods collective case study of a defined, diverse geographic postcode area in the United Kingdom. Methods: Quantitative retrospective analysis of electronic and paper medical records of adult PI patients from 2015 district nursing reports. Qualitative semi-structured interviews of community dwelling adult patients receiving, or received, treatment for PI in 2016. Results: Mandatory reports (n = 103) revealed that 90 patients were supplied with a variety of pressure-redistributing devices but only one-third of patients used the equipment as recommended. Qualitative interviews (n = 12), reported to COREQ guidelines, revealed that patients felt reliant on community health services, and were concerned about the consistency of their care. Conclusions: Authentic patient involvement is required to provide care and interventions that are acceptable to PI patients and can be incorporated into self-care strategies and effectively monitored.

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.

Health literacy in pressure injury: findings from a mixed methods study of community-based patients and carers

The present study, drawn from a larger mixed-methods case study, provides insights into the health literacy of community-based patients with pressure injuries, and their carers, and critically analyzes the patient information resources available; crucial because health literacy is associated with patient care and outcomes for patients. Two datasets were used to better understand patient literacy in relation to pressure injury: (i) narratives from patients and carers; and (ii) analysis of patient education resources. Narratives were subject to content analysis and patient education resources available to the patients were analyzed drawing on the Simplified Measure of Gobbledygook, the National Health Service Toolkit for Producing Patient Resources, and compared to an internationally-advocated pressure injury leaflet. The study findings indicated that despite leaflets broadly meeting required production and content guidelines, patients appeared to poorly engage with these materials and demonstrated limited health literacy in relation to pressure injury. Although improvements in leaflet production and readability might be advantageous, emphasis should remain on quality patient-health-care professional relationships to enable tailored patient education that can enhance awareness and engagement with treatment and prevention interventions.

PO-0706: Individualised margin calculations for different target regions in anal cancer IMRT

Purpose/Objective: UK IMRT anal cancer treatment uses large fields to uninvolved nodal groups (40Gy) with simultaneous integrated boost to the primary tumour (50.4Gy T1/T2; 53.2Gy T3/T4) and involved nodes (50.4Gy). With a simple bony match online, iliac nodes are well covered and the margins required are well documented, however the margins for prophylactic inguinal nodes (pIN) and primary tumour are not well established as data from daily imaging are limited; these form the focus of this study. Materials and Methods: Anal cancer patients treated at a single institution under current UK IMRT guidelines were screened; 11 consecutive inguinal node negative patients were studied. Supine treatment comprised 28 fractions with daily imaging: CBCT fractions 1-5, 10, 15, 20 and 25; orthogonal kV imaging all other fractions. 99 CBCT’s were re-matched automatically to the planning CT. A bony match was performed using a clipbox encompassing the bony pelvis. Re-matches were performed within the same clipbox using the clinician defined tumour (GTVA) as a region of interest (ROI), then repeated with the pIN ROI. Accuracy of auto-matches were assessed visually to ensure clinical relevance. Bony match values were subtracted from the GTVA and pIN measurements to evaluate differences in the optimal treatment position for the tumour or the nodes relative to a simple bony match. Margins were calculated using van Herk’s recipe. Results: Differences (mm) between GTVA/ bony matches were larger than inguinal/ bony matches in all axes ( lat -3.1 to 4.2; -2 to 1.5, vert6.9 to 12.7; -3.6 to 2.9, long -13.3 to 17.2; -8.5 to 7.3 in GTV and pIN respectively). This was statistically significant in the long axis (p<0.05) shown in Fig.1. GTVA had consistently larger systematic and random errors than pIN, reflected in the margin calculations (mm): GTVA lat 2.8, long 9.8, vert 5.8; pIN lat 1.5, long 3.1, vert 3.1. Conclusions: With a simple bony match, the margin around pIN can be reduced to 1.5mm laterally and 3.1mm in all other directions potentially reducing toxicity to the groin, genitalia and bladder. The GTVA to PTV margin incorporates microscopic disease, the motion of the soft tissues of the anus which can be affected by tumour size, location, bowel filling and BMI; and the set up error. The margin reported in this study covers set up error and soft tissue motion of the anus. An individualised margin incorporating these factors can be calculated and applied during the treatment course with the aim of reducing toxicity in adjacent organs such as vagina, bladder and penile bulb. Further investigation is warranted to demonstrate reduced toxicities with these strategies.

Volumetric analysis of anal cancer relapses following radical chemoradiation.

576 Background: Definitive chemoradiotherapy is standard of care in anal squamous cell carcinoma. The ACT II trial set the standard achieving three year overall survival rates of 73%. However patients with locally advanced disease have a ~50% local relapse rate. Studies have failed to demonstrate an improvement in local relapse rate by altering the systemic therapy. Although 2/3 of relapses are local as opposed to regional or distant, there is limited knowledge on the 3D position of these relapses. We aim to retrospectively review the patterns of local failure in three dimensions, relative to the radiotherapy plan. Methods: Between February 2007 and April 2012, 77 patients were treated for squamous cell carcinoma of the anus with radical chemoradiotherapy. Early stage (T0/2) and locally advanced (T3/4) tumours constituted 53% and 44% respectively. 37% of patients had nodal disease. As per ACT II protocol we used a gross tumour volume (GTV) to PTV margin of 3cm and prescribed to a dose of 50.4Gy. In patien...