K. Franks

Radiotherapy for Node Positive Penile Cancer: Experience of The Leeds Teaching Hospitals

PURPOSE We studied the outcomes in patients with node positive penile cancer who received radiotherapy to inguinal and pelvic nodes. Although half of node positive cases are cured by lymphadenectomy, little data are available on the potential further benefits and toxicities of postoperative radiotherapy. MATERIALS AND METHODS We retrospectively audited the clinical notes and electronic records of 23 patients referred to a specialist center from 2002 to 2008 who received radiotherapy to the inguinal/pelvic nodes as adjuvant treatment after lymphadenectomy (14), or as high grade palliation for extensive/fixed nodes (8) or extensive local tumor (1). The primary outcome measure was overall survival. Secondary end points were locoregional recurrence-free survival and toxicity. RESULTS All 13 deaths were due to penile cancer. Patients with adjuvant therapy had better overall survival (66% vs 11%, p<0.001) and locoregional relapse-free survival (56% vs 22%, p=0.03) than those with high grade palliation. Six of 14 adjuvant cases and 7 of 9 with high grade palliation relapsed locoregionally. Of patients with adjuvant therapy and extracapsular spread 1 of 6 with N1, 1 of 4 with N2 and 3 of 4 with N3 disease relapsed (p=0.31). No life threatening toxicity was observed. It was difficult to determine the relative contributions of radiotherapy and surgery to leg/scrotal lymphedema. The study was limited by its small size, which reflects the rarity of this tumor. CONCLUSIONS Adjuvant radiotherapy appears to have a role after inguinal lymphadenectomy, particularly in patients with extracapsular nodal spread, in whom historically survival rates have been poor. Our findings warrant further investigation in larger series of patients.

The evaluation of a deformable image registration segmentation technique for semi-automating internal target volume (ITV) production from 4DCT images of lung stereotactic body radiotherapy (SBRT) patients.

PURPOSE To evaluate a deformable image registration (DIR) segmentation technique for semi-automating ITV production from 4DCT for lung patients, in terms of accuracy and efficiency. METHODS Twenty-five stereotactic body radiotherapy lung patients were selected in this retrospective study. ITVs were manually delineated by an oncologist and semi-automatically produced by propagating the GTV manually delineated on the mid-ventilation phase to all other phases using two different DIR algorithms, using commercial software. The two ITVs produced by DIR were compared to the manually delineated ITV using the dice similarity coefficient (DSC), mean distance between agreement and normalised DSC. DIR-produced ITVs were assessed for their clinical suitability and also the time savings were estimated. RESULTS Eighteen out of 25 ITVs had normalised DSC>1 indicating an agreement with the manually produced ITV within 1mm uncertainty. Four of the other seven ITVs were deemed clinically acceptable and three would require a small amount of editing. In general, ITVs produced by DIR were smoother than those produced by manual delineation. It was estimated that using this technique would save clinicians on average 28 min/patient. CONCLUSIONS ABAS was found to be a useful tool in the production of ITVs for lung patients. The ITVs produced are either immediately clinically acceptable or require minimal editing. This approach represents a significant time saving for clinicians.

Practical Considerations Arising from the Implementation of Lung Stereotactic Body Radiation Therapy (SBRT) at a Comprehensive Cancer Center

Introduction: With the anticipation of improved outcomes, especially for patients with early-stage non-small cell lung cancer, stereotactic body radiation therapy (SBRT) has been rapidly introduced into the thoracic radiation oncology community. Although at first glance lung SBRT might seem methodologically similar to conventional radiotherapy, there are important differences in its execution that require particular consideration. The objective of this paper is to highlight these and other issues to contribute to the safe and effective diffusion of lung SBRT. We discuss practical challenges that have been encountered in the implementation of lung SBRT at a single, large institution and emphasize the importance of a systematic approach to the design of lung SBRT services. Methods: Specific technical and clinical components that were identified as being important during the development of lung SBRT at Princess Margaret Hospital are described. The clinical system that evolved from these is outlined. Results: Using this clinical framework the practical topics addressed include: patient assessment, simulation and treatment planning, tumor and organ at risk delineation, trial set up before treatment, on-line image-guidance, and patient follow-up. Conclusions: The potential gain in therapeutic ratio that is theoretically possible with lung SBRT can only be realized if the tumor is adequately irradiated and normal tissue spared. A discussion of the component parts of lung SBRT is presented. It is a complex process and specific challenges need to be overcome to effect the satisfactory transition of lung SBRT into routine practice.

Radiation-induced second primary cancer risks from modern external beam radiotherapy for early prostate cancer: impact of stereotactic ablative radiotherapy (SABR), volumetric modulated arc therapy (VMAT) and flattening filter free (FFF) radiotherapy

Risks of radiation-induced second primary cancer following prostate radiotherapy using 3D-conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT), flattening filter free (FFF) and stereotactic ablative radiotherapy (SABR) were evaluated. Prostate plans were created using 10 MV 3D-CRT (78 Gy in 39 fractions) and 6 MV 5-field IMRT (78 Gy in 39 fractions), VMAT (78 Gy in 39 fractions, with standard flattened and energy-matched FFF beams) and SABR (42.7 Gy in 7 fractions with standard flattened and energy-matched FFF beams). Dose-volume histograms from pelvic planning CT scans of three prostate patients, each planned using all 6 techniques, were used to calculate organ equivalent doses (OED) and excess absolute risks (EAR) of second rectal and bladder cancers, and pelvic bone and soft tissue sarcomas, using mechanistic, bell-shaped and plateau models. For organs distant to the treatment field, chamber measurements recorded in an anthropomorphic phantom were used to calculate OEDs and EARs using a linear model. Ratios of OED give relative radiation-induced second cancer risks. SABR resulted in lower second cancer risks at all sites relative to 3D-CRT. FFF resulted in lower second cancer risks in out-of-field tissues relative to equivalent flattened techniques, with increasing impact in organs at greater distances from the field. For example, FFF reduced second cancer risk by up to 20% in the stomach and up to 56% in the brain, relative to the equivalent flattened technique. Relative to 10 MV 3D-CRT, 6 MV IMRT or VMAT with flattening filter increased second cancer risks in several out-of-field organs, by up to 26% and 55%, respectively. For all techniques, EARs were consistently low. The observed large relative differences between techniques, in absolute terms, were very low, highlighting the importance of considering absolute risks alongside the corresponding relative risks, since when absolute risks are very low, large relative risks become less meaningful. A calculated relative radiation-induced second cancer risk benefit from SABR and FFF techniques was theoretically predicted, although absolute radiation-induced second cancer risks were low for all techniques, and absolute differences between techniques were small.

Prostate Stereotactic Ablative Radiation Therapy Using Volumetric Modulated Arc Therapy to Dominant Intraprostatic Lesions

Purpose To investigate boosting dominant intraprostatic lesions (DILs) in the context of stereotactic ablative radiation therapy (SABR) and to examine the impact on tumor control probability (TCP) and normal tissue complication probability (NTCP). Methods and Materials Ten prostate datasets were selected. DILs were defined using T2-weighted, dynamic contrast-enhanced and diffusion-weighted magnetic resonance imaging. Four plans were produced for each dataset: (1) no boost to DILs; (2) boost to DILs, no seminal vesicles in prescription; (3) boost to DILs, proximal seminal vesicles (proxSV) prescribed intermediate dose; and (4) boost to DILs, proxSV prescribed higher dose. The prostate planning target volume (PTV) prescription was 42.7 Gy in 7 fractions. DILs were initially prescribed 115% of the PTVProstate prescription, and PTVDIL prescriptions were increased in 5% increments until organ-at-risk constraints were reached. TCP and NTCP calculations used the LQ-Poisson Marsden, and Lyman-Kutcher-Burman models respectively. Results When treating the prostate alone, the median PTVDIL prescription was 125% (range: 110%-140%) of the PTVProstate prescription. Median PTVDIL D50% was 55.1 Gy (range: 49.6-62.6 Gy). The same PTVDIL prescriptions and similar PTVDIL median doses were possible when including the proxSV within the prescription. TCP depended on prostate α/β ratio and was highest with an α/β ratio = 1.5 Gy, where the additional TCP benefit of DIL boosting was least. Rectal NTCP increased with DIL boosting and was considered unacceptably high in 5 cases, which, when replanned with an emphasis on reducing maximum dose to 0.5 cm3 of rectum (Dmax0.5cc), as well as meeting existing constraints, resulted in considerable rectal NTCP reductions. Conclusions Boosting DILs in the context of SABR is technically feasible but should be approached with caution. If this therapy is adopted, strict rectal constraints are required including Dmax0.5cc. If the α/β ratio of prostate cancer is 1.5 Gy or less, then high TCP and low NTCP can be achieved by prescribing SABR to the whole prostate, without the need for DIL boosting.

Second Primary Cancers Occurring after I-125 Brachytherapy as Monotherapy for Early Prostate Cancer

AIMS Prostate brachytherapy may be associated with a lower risk of radiation-induced second primary cancer (SPC) as a significantly smaller volume of normal tissue is irradiated when compared with external beam techniques. Limited data are available as it has been a routine treatment option for less than 20 years. This study identified cases of SPC in patients who underwent I-125 prostate brachytherapy as monotherapy in a single institution. MATERIALS AND METHODS SPC incidence was retrieved by conducting a UK cancer registry search (Northern and Yorkshire Cancer Registry and Information Service) for 1805 consecutive patients with localised prostate cancer who received monotherapy with I-125 brachytherapy from 1995 to 2006 at a single public hospital. Of 1730 UK residents, the completeness of the registry match was 91% (1574 patients). The mean age at treatment (interquartile range) of the cohort was 63 (58-68) years with 1100 patients (70%) over the age of 60 years at treatment. The median (range) follow-up was 8 (6-10) years with 487 patients (31%) having 10 years or more. RESULTS In total, 170 patients (10.8%) were diagnosed with second primaries (1 year or more after implant); 20 of these were bladder and 10 rectal cancers. The 10 year cumulative incidences were 14.6, 1 and 0.84% for any second malignancy, bladder and rectal cancer, respectively. Only the standardised incidence rate (SIR) for bladder cancer was higher at 1.54 (95% confidence interval 0.96-2.46) compared with the general population. The SIR for bladder cancer was higher in the first few years after treatment, suggesting that the increased incidence of bladder cancer is due to increased urological surveillance. CONCLUSIONS Overall, the incidence of SPC after I-125 is comparable with other published data with no significant excess more than 5 years from treatment. Mortality secondary to SPC of the bladder or rectum is unusual.

A systematic review of outcomes following Stereotactic Ablative Radiotherapy in the treatment of early stage primary lung cancer.

Stereotactic ablative body radiotherapy (SABR) describes a radiotherapy (RT) technique where high doses of radiation are precisely delivered to an extracranial target within the body, using either a single fraction of RT or using multiple small numbers of fractions. SABR has now become the standard of care treatment for patients with early-stage non-small-cell lung cancer (NSCLC) for whom surgery is not appropriate. This systematic review considers the evidence supporting the use of SABR in early-stage NSCLC, reported toxicity rates, the use of SABR in centrally located NSCLC, the use of SABR as salvage therapy following surgery or RT, and future potential drug combinations with SABR.

UK Consensus on Normal Tissue Dose Constraints for Stereotactic Radiotherapy

Six UK studies investigating stereotactic ablative radiotherapy (SABR) are currently open. Many of these involve the treatment of oligometastatic disease at different locations in the body. Members of all the trial management groups collaborated to generate a consensus document on appropriate organ at risk dose constraints. Values from existing but older reviews were updated using data from current studies. It is hoped that this unified approach will facilitate standardised implementation of SABR across the UK and will allow meaningful toxicity comparisons between SABR studies and internationally.

Protocol for the isotoxic intensity modulated radiotherapy (IMRT) in stage III non-small cell lung cancer (NSCLC): a feasibility study

Introduction The majority of stage III patients with non-small cell lung cancer (NSCLC) are unsuitable for concurrent chemoradiotherapy, the non-surgical gold standard of care. As the alternative treatment options of sequential chemoradiotherapy and radiotherapy alone are associated with high local failure rates, various intensification strategies have been employed. There is evidence to suggest that altered fractionation using hyperfractionation, acceleration, dose escalation, and individualisation may be of benefit. The MAASTRO group have pioneered the concept of ‘isotoxic’ radiotherapy allowing for individualised dose escalation using hyperfractionated accelerated radiotherapy based on predefined normal tissue constraints. This study aims to evaluate whether delivering isotoxic radiotherapy using intensity modulated radiotherapy (IMRT) is achievable. Methods and analysis Isotoxic IMRT is a multicentre feasibility study. From June 2014, a total of 35 patients from 7 UK centres, with a proven histological or cytological diagnosis of inoperable NSCLC, unsuitable for concurrent chemoradiotherapy will be recruited. A minimum of 2 cycles of induction chemotherapy is mandated before starting isotoxic radiotherapy. The dose of radiation will be increased until one or more of the organs at risk tolerance or the maximum dose of 79.2 Gy is reached. The primary end point is feasibility, with accrual rates, local control and overall survival our secondary end points. Patients will be followed up for 5 years. Ethics and dissemination The study has received ethical approval (REC reference: 13/NW/0480) from the National Research Ethics Service (NRES) Committee North West—Greater Manchester South. The trial is conducted in accordance with the Declaration of Helsinki and Good Clinical Practice (GCP). The trial results will be published in a peer-reviewed journal and presented internationally. Trial registration number NCT01836692; Pre-results.

Occult Nodal Disease in Patients With Non–Small-Cell Lung Cancer Who are Suitable for Stereotactic Ablative Body Radiation

INTRODUCTION Stereotactic ablative body radiotherapy is a therapeutic option for patients with peripheral stage I NSCLC in whom surgical resection is considered high risk. Patients receiving SABR do not undergo systematic nodal dissection and any occult nodal metastases will therefore go undetected. Our aim was to determine what proportion of cases this might represent. MATERIALS AND METHODS We retrospectively studied patients who underwent lung resections for presumed stage I NSCLC between 2008 and 2011 at a United Kingdom teaching hospital. We reviewed postoperative pathological lymph node staging and analyzed a subset of these patients in whom SABR would have been be technically possible. RESULTS We reviewed 128 cases of presumed NSCLC preoperatively staged as T1/2a N0 M0. Of 89 cases with peripheral tumor location, 8 patients (8.9%) had nodal involvement at surgical resection. CONCLUSION Our data show that approximately 1 in 11 patients with peripheral stage I NSCLC will have occult mediastinal/hilar nodal involvement. Although this is a relatively small proportion, routine use of EBUS-TBNA for nodal staging in patients undergoing SABR might identify a greater proportion of patients with nodal disease compared with a strategy of nodal staging directed according to positron emission tomography-computed tomography findings.