Differential Response of Pelvic Bone Marrow Fluorodeoxyglucose Uptake in Patients Receiving Concurrent Chemoradiotherapy.

AIMS: Irradiation of pelvic bone marrow (PBM) at the level of the typical low dose bath of intensity-modulated radiotherapy delivery (10-20 Gy) is associated with an increased risk of haematological toxicity, particularly when combined with concurrent chemotherapy. Although sparing of the whole of the PBM at a 10-20 Gy dose level is unachievable, it is known that PBM is divided into haematopoietically active and inactive regions that are identifiable based on the threshold uptake of [18F]-fluorodeoxyglucose (FDG) seen on positron emission tomography-computed tomography (PET-CT). In published studies to date, the definition of active PBM widely used is that of a standardised uptake value (SUV) greater than the mean SUV of the whole PBM prior to the start of chemoradiation. These studies include those looking at developing an atlas-based approach to contouring active PBM. Using baseline and mid-treatment FDG PET scans acquired as part of a prospective clinical trial we sought to determine the suitability of the current definition of active bone marrow as representative of differential underlying cell physiology. MATERIALS AND METHODS: Active and inactive PBM were contoured on baseline PET-CT and using deformable registration mapped onto mid-treatment PET-CT. Volumes were cropped to exclude definitive bone, voxel SUV extracted and the change between scans calculated. Change was compared using Mann-Whitney U testing. RESULTS: Active and inactive PBM were shown to respond differentially to concurrent chemoradiotherapy. The median absolute response of active PBM for all patients was -0.25 g/ml, whereas the median inactive PBM response was -0.02 g/ml. Significantly, the inactive PBM median absolute response was shown to be near zero with a relatively unskewed distribution (0.12). CONCLUSIONS: These results would support the definition of active PBM as FDG uptake greater than the mean of the whole structure as being representative of underlying cell physiology. This work would support the development of atlas-based approaches published in the literature to contour active PBM based on the current definition as being suitable.

Potential for Isotoxic Re-irradiation Stereotactic Ablative Body Radiotherapy in Locally Recurrent Rectal Cancer.

AIMS: The non-surgical management of locally recurrent rectal cancer (LRRC) is an area of unmet need, with no defined standard treatment and extremely poor outcomes. Patients typically receive radiotherapy during initial multimodality treatment and historically re-irradiation has been limited to conservative doses with subsequent short-term symptom control. Recently, stereotactic ablative body radiotherapy (SABR) has shown promise in re-irradiation of LRRC in England, but is limited to a relatively modest dose prescription of 30Gy in five fractions. We propose that SABR can be achieved in LRRC to higher doses using an isotoxic dose prescription with fixed 15% per annum tissue recovery for acceptable organ at risk (OAR) constraints. MATERIALS AND METHODS: Patients with LRRC at a local centre treated with SABR re-irradiation were audited. Patients were identified, the dose and time since previous radiotherapy determined, re-irradiation OAR constraints calculated and retrospective re-planning carried out. RESULTS: In patients currently receiving SABR (17 patients, 21 targets), dose escalation above 30 Gy in five fractions was achievable, with a biological effective dose of 80 Gy (alpha/beta = 10) deliverable to 80% or more of the planning target volume in eight of the 21 targets. CONCLUSIONS: Isotoxic SABR re-irradiation should be considered a potential treatment option for LRRC to maximise patient outcomes while limiting excess toxicity. Although probably conservative, clinical outcome data are needed to determine the suitability of OAR constraints using 15% per annum tissue recovery and the impact on local control rates, patient quality of life and overall survival of isotoxic SABR.

The Long and the Short of it: the Role of Short-course Radiotherapy in the Neoadjuvant Management of Rectal Cancer.

Total mesorectal excision is the cornerstone of treatment for rectal cancer. Multiple randomised trials have shown a reduction in local recurrence rates with the addition of preoperative radiotherapy, either as a 1-week hypofractionated short-course (SCRT) or a conventionally fractionated long-course (LCRT) schedule with concurrent chemotherapy. There is also increasing interest in the addition of neoadjuvant chemotherapy to radiotherapy with the aim of improving disease-free survival. The relative use of SCRT and LCRT varies considerably across the world. This is reflected in, and is probably driven in part by, disparity between international guideline recommendations. In addition, different approaches to treatment may exist both between and within countries, with variation related to patient, disease and treatment centre and financial factors. In this review, we will specifically focus on the use of SCRT for the treatment of rectal cancer. We will discuss the literature base and current guidelines, highlighting the challenges and controversies in clinical application of this evidence. We will also discuss potential future applications of SCRT, including its role in optimisation and intensification of treatment for rectal cancer.

Multicentre Investigation of Prognostic Factors Incorporating p16 and Tumour Infiltrating Lymphocytes for Anal Cancer After Chemoradiotherapy.

AIMS: Anal squamous cell carcinomas (ASCC) are strongly associated with human papillomaviruses. Standard of care is chemoradiotherapy at uniform doses with no treatment stratification. Immunohistochemical staining for p16INK4A (p16), a surrogate for human papillomaviruses, is prognostic for outcomes. We investigated this alongside clinical-pathological factors, including tumour infiltrating lymphocyte (TIL) scores. MATERIALS AND METHODS: Using an independent, multicentre cohort of 257 ASCC treated with chemoradiotherapy, pretreatment biopsies were stained and scored for p16 and TIL. Kaplan-Meier curves were derived for outcomes (disease-free survival [DFS], overall survival and cancer-specific survival), by stage, p16 and TIL scores and Log-rank tests were carried out to investigate prognostic effect. A multivariate analysis was carried out using Cox regression. RESULTS: Stage, sex, p16 and TILs were independently prognostic. Hazard ratios for death (overall survival) were 2.51 (95% confidence interval 1.36-4.63) for p16 negative versus p16 positive, 2.17 (1.34-3.5) for T3/4 versus T1/2, 2.42 (1.52-3.8) for males versus females and 3.30 (1.52-7.14) for TIL1 versus TIL3 (all P < 0.05). CONCLUSIONS: We have refined prognostic factors in ASCC. p16 adds to stratification by stage with respect to DFS in early disease and overall survival/DFS in locally advanced cancers. Our data support the role of the host immune response in mediating outcomes. These factors will be prospectively evaluated in PLATO (ISRCTN88455282).

Intensity-modulated Radiotherapy for Rectal Cancer in the UK in 2020.

AIMS: Preoperative (chemo)radiotherapy followed by total mesorectal excision is the current standard of care for patients with locally advanced rectal cancer. The use of intensity-modulated radiotherapy (IMRT) for rectal cancer is increasing in the UK. However, the extent of IMRT implementation and current practice was not previously known. A national survey was commissioned to investigate the landscape of IMRT use for rectal cancer and to inform the development of national rectal cancer IMRT guidance. MATERIALS AND METHODS: A web-based survey was developed by the National Rectal Cancer IMRT Guidance working group in collaboration with the Royal College of Radiologists and disseminated to all UK radiotherapy centres. The survey enquired about the implementation of IMRT with a focus on the following aspects of the workflow: dose fractionation schedules and use of a boost; pre-treatment preparation and simulation; target volume/organ at risk definition; treatment planning and treatment verification. A descriptive statistical analysis was carried out. RESULTS: In total, 44 of 63 centres (70%) responded to the survey; 30/44 (68%) and 36/44 (82%) centres currently use IMRT to treat all patients and selected patients with rectal cancer, respectively. There was general agreement concerning several aspects of the IMRT workflow, including patient positioning, use of intravenous contrast and bladder protocols. Greater variation in practice was identified regarding rectal protocols; use of a boost to primary/nodal disease; target volume delineation; organ at risk delineation and dose constraints and treatment verification. Delineation of individual small bowel loops and daily volumetric treatment verification were considered potentially feasible by most centres. CONCLUSION: This survey identified that IMRT is already used to treat rectal cancer in many UK radiotherapy centres, but there is heterogeneity between centres in its implementation and practice. These results have been a valuable aid in framing the recommendations within the new National Rectal Cancer IMRT Guidance.

A Prospective Study of Diffusion-weighted Magnetic Resonance Imaging as an Early Prognostic Biomarker in Chemoradiotherapy in Squamous Cell Carcinomas of the Anus.

AIMS: The use of diffusion-weighted magnetic resonance imaging (DW-MRI) as a prognostic marker of treatment response would enable early individualisation of treatment. We aimed to quantify the changes in mean apparent diffusion coefficient (ΔADCmean) between a DW-MRI at diagnosis and on fraction 8-10 of chemoradiotherapy (CRT) as a biomarker for cellularity, and correlate these with anal squamous cell carcinoma recurrence. MATERIALS AND METHODS: This prospective study recruited patients with localised anal cancer between October 2014 and November 2017. DW-MRI was carried out at diagnosis and after fraction 8-10 of radical CRT. A region of interest was delineated for all primary tumours and any lymph nodes >2 cm on high-resolution T2-weighted images and propagated to the ADC map. Routine clinical follow-up was collected from Nation Health Service electronic systems. RESULTS: Twenty-three of 29 recruited patients underwent paired DW-MRI scans. Twenty-six regions of interest were delineated among the 23 evaluable patients. The median (range) tumour volume was 13.6 cm3 (2.8-84.9 cm3). Ten of 23 patients had lesions with ΔADCmean ≤ 20%. With a median follow-up of 41.2 months, four patients either failed to have a complete response to CRT or subsequently relapsed. Three of four patients with disease relapse had lesions demonstrating ΔADCmean <20%, the other patient with persistent disease had ΔADCmean of 20.3%. CONCLUSIONS: We demonstrated a potential correlation between patients with ΔADCmean <20% and disease relapse. Further investigation of the prognostic merit of DW-MRI change is needed in larger, prospective cohorts.

Impact of compliance to chemoradiation on long-term outcomes in squamous cell carcinoma of the anus: results of a post hoc analysis from the randomised phase III ACT II trial.

BACKGROUND: Concurrent chemoradiation is standard-of-care for patients with squamous cell carcinoma of the anus. Poor compliance to chemotherapy, radiotherapy treatment interruptions and unplanned breaks may impact adversely on long-term outcomes. METHODS: The ACT II trial recruited 940 patients with localised squamous cell carcinoma of the anus, and assigned patients to mitomycin (week 1) or cisplatin (weeks 1 and 5), with fluorouracil (weeks 1 and 5) and radiotherapy (50.4 Gy in 28 fractions over 38 days). This post hoc analysis examined the association between baseline factors (age, gender, site, T stage and N stage), and compliance to treatment (radiotherapy and chemotherapy), and their effects on locoregional failure-free survival, progression-free survival (PFS) and overall survival (OS). Compliance was categorised into groups. Radiotherapy: six groups according to total dose and overall treatment time (OTT). Chemotherapy: three groups (A = per-protocol; B = dose reduction or delay; C = omitted). RESULTS: A total of 931/940 patients were assessable for radiotherapy and 936 for chemotherapy compliance. Baseline glomerular filtration rate <60 ml/min and cisplatin were significantly associated with poor week 5 compliance to chemotherapy (P = 0.003 and 0.02, respectively). Omission of week 5 chemotherapy was associated with significantly worse locoregional failure-free survival [hazard ratio (HR) 2.53 (1.33-4.82) P = 0.005]. Dose reductions/delays or omission of week 5 chemotherapy were associated with significantly worse PFS {HR: 1.56 [95% confidence interval (CI): 1.18-2.06], P = 0.002 and HR: 2.39 (95% CI: 1.44-3.98), P = 0.001, respectively} and OS [HR: 1.92 (95% CI: 1.41-2.63), P < 0.001 and HR: 2.88 (95% CI: 1.63-5.08), P < 0.001, respectively]. Receiving the target radiotherapy dose in >42 days is associated with worse PFS and OS [HR: 1.72 (95% CI: 1.17-2.54), P =0.006]. CONCLUSION: Poor compliance to chemotherapy and radiotherapy were associated with worse locoregional failure-free survival, PFS and OS. Treatment interruptions should be minimised, and OTT and total dose maintained. CLINICAL TRIAL NUMBER: ISRCTN 26715889.

UK national cohort of anal cancer treated with intensity-modulated radiotherapy: One-year oncological and patient-reported outcomes.

BACKGROUND: Concurrent chemoradiotherapy is the standard treatment for anal cancer. Following national UK implementation of intensity-modulated radiotherapy (IMRT), this prospective, national cohort evaluates the one-year oncological outcomes and patient-reported toxicity outcomes (PRO) after treatment. MATERIALS AND METHODS: A national cohort of UK cancer centers implementing IMRT was carried out between February to July 2015. Cancer centers provided data on oncological outcomes, including survival, and disease and colostomy status at one-year. EORTC-QLQ core (C30) and colorectal (CR29) questionnaires were completed at baseline and one-year followup. The PRO scores at baseline and one year were compared. RESULTS: 40 UK Cancer Centers returned data with a total of 187 patients included in the analysis. 92% received mitomycin with 5-fluorouracil or capecitabine. One-year overall survival was 94%; 84% were disease-free and 86% colostomy-free at one-year followup. At one year, PRO results found significant improvements in buttock pain, blood and mucus in stools, pain, constipation, appetite loss, and health anxiety compared to baseline. No significant deteriorations were reported in diarrhea, bowel frequency, and flatulence. Urinary symptom scores were low at one year. Moderate impotence symptoms at baseline remained at one year, and a moderate deterioration in dyspareunia reported. CONCLUSIONS: With national anal cancer IMRT implementation, at this early pre-defined time point, one-year oncological outcomes were reassuring and resulted in good disease-related symptom control. one-year symptomatic complications following CRT for anal cancer using IMRT techniques appear to be relatively mild. These PRO results provide a basis to benchmark future studies.

Neoadjuvant radiotherapy in rectal cancer - less is more?

AIM: There is significant international variation in the use of neoadjuvant radiation prior to total mesorectal excision. The MERCURY group advocate selective neoadjuvant chemoradiotherapy (CRT). We have performed a retrospective, single-centre study of patients treated with CRT, where only the circumferential resection margin is threatened, with the aim of identifying whether a more selective approach to CRT provides acceptable local relapse rates (LRRs). METHOD: All consecutive patients who underwent radical surgery for rectal adenocarcinoma over a 5-year period (2007-2012) in the Oxford University Trust were considered. Electronic hospital systems were reviewed to obtain patient and tumour demographics, treatment and follow-up information. All patients were classified into risk categories according to National Institute for Health and Care Excellence guidance. Data were analysed using Microsoft Excel and R. RESULTS: Two hundred and seventy-two patients were identified: 123, 89 and 60 in the high-, intermediate- and low-risk categories, respectively. Seventy-nine per cent of those in the high-risk group, 6% in the intermediate and 5% in the low-risk group underwent CRT. The overall 5-year LRR and distant recurrence rate (DRR) were 5.2% and 17.8%, respectively. The 5-year LRR for those who went straight to surgery was 2.0% and for those who had neoadjuvant CRT it was 7.4%. The DRR for these two groups was 8.5% and 18.9%, respectively. CONCLUSION: Our series demonstrates that the use of CRT only in margin-threatening tumours, results in an exceptionally low LRR for those without margin-threatening disease. In routine clinical care, this strategy can minimize the significant morbidity of multimodal treatment and allow earlier introduction of systemic therapy to minimize distant recurrence.

Intensity-Modulated Radiotherapy With a Simultaneous Integrated Boost in Rectal Cancer.

AIMS: Dose-response curves suggest that higher doses of radiotherapy improve the complete response rate in rectal cancer. The UK adopted the EXPERT trial dose and fractionation, 45 Gy in 25 fractions to the pelvis with a sequential 9 Gy in five fractions to the gross tumour, in patients where the aim was to maximise the complete response. In the Oxford University Hospital NHS Foundation Trust (Oxford, UK) we deliver a biological equivalent dose (BED5) in selected patients using intensity-modulated radiotherapy (IMRT) with a simultaneous integrated boost (SIB) in 25 fractions. We carried out a retrospective analysis of our series to: (i) document the toxicity of this protocol; (ii) ascertain whether dose constraints from RTOG 0822 were appropriate; (iii) assess the response. MATERIALS AND METHODS: The demographics and treatment details for all consecutive patients treated with this protocol were collected using electronic systems. Patients received 45 Gy to the elective nodes and 52 Gy using a SIB to the gross tumour with capecitabine chemotherapy using IMRT or RapidArc plans. Acute toxicity was collected prospectively during weekly reviews. For the purpose of this study, a dedicated gastrointestinal radiologist reviewed all baseline and post-treatment magnetic resonance images and assigned a magnetic resonance tumour regression grade (mrTRG). RESULTS: Seventy-one patients were identified. Seventy completed radiotherapy with a median overall treatment time of 34 days (range 32-36 days); 67.6% received full-dose chemotherapy, with 21.2% receiving a reduced dose. There was a 4.2% incidence of grade 3+ non-haematological toxicity and 1.5% grade 3 + haematological toxicity. 4.2% were admitted during their radiotherapy, with one death due to a pelvic abscess. The RTOG 0822 constraints were achieved in ≥75% of cases, other than the high-dose bladder constraint. mrTRG 1-2 was seen in 47.8%, with mrTRG 1 seen in 23.9%. CONCLUSIONS: We suggest that our protocol shows acceptable acute toxicity, with promising mrTRG results, and could be adopted by centres as an IMRT equivalent dose for EXPERT dose and fractionation.