Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique.

BACKGROUND: Volumetric Modulated Arc Therapy (VMAT) offers better conformity, homogeneity and sparing of the heart and ipsilateral lung for locoregional radiotherapy in left-sided breast cancer compared to three-dimensional conformal radiotherapy (3D-CRT). However, conventional coplanar VMAT (cVMAT) can result in higher doses to the normal tissue on the contralateral side. This study investigates a non-coplanar VMAT-technique (ncVMAT) to mitigate this issue. MATERIAL AND METHODS: CT series of 20 left sided breast cancer patients were included for planning of locoregional breast radiotherapy including internal mammary nodes (IMN). Three treatment plans; 3D-CRT, cVMAT and ncVMAT, were generated for each patient with a prescription dose of 40.05 Gy in 15 fractions. Both VMAT-techniques consisted of a single arc in the axial plane, while ncVMAT included an additional arc in the sagittal plane. All plans were optimized to cover the clinical target volume (CTV) by 38.05 Gy for the breast and 36.05 Gy for lymph nodes, with as low as possible dose to organs at risk. RESULTS: Full CTV coverage was achieved for all plans. Both cVMAT and ncVMAT delivered more conformal and homogeneous target doses than 3D-CRT. Doses to the heart and ipsilateral lung were significantly lower with ncVMAT compared to both cVMAT and 3D-CRT. ncVMAT reduced doses to both the contralateral breast and lung compared to cVMAT and achieved levels similar to 3D-CRT for the contralateral breast and moderately higher doses for the contralateral lung. Delivery of high doses (>30 Gy) to the contralateral side was completely avoided with ncVMAT, contrary to the results for cVMAT and 3D-CRT. CONCLUSION: ncVMAT reduced doses to the heart and ipsilateral lung as compared to both cVMAT and 3D-CRT. All contralateral dose metrics were reduced with the novel ncVMAT technique compared to cVMAT, and the mean contralateral breast doses were similar to 3D-CRT.

Script-based automatic radiotherapy planning for cervical cancer.

BACKGROUND: This study aimed to develop fully automated script-based radiotherapy treatment plans for cervical cancer patients, and evaluate them against clinically accepted plans, as validation before clinical implementation. MATERIAL AND METHODS: In this retrospective planning study, treatment plans for 25 locally advanced cervical cancer (LACC) patients with up to three dose levels were included. Fully automated plans were created using an in-house developed Python script in RayStation, and compared to clinically accepted manually made plans. Quantitatively, relevant dose statistics were compared, and average dose volume histograms (DVHs) were analyzed. Qualitatively, a blinded plan comparison was conducted between the clinical and automatic plans. The accuracy of treatment plan delivery was verified with the Delta4 Phantom+. RESULTS: The quantitative evaluation showed that target coverage was acceptable for all the automatic and clinical plans. The automatic plans were significantly more conformal than the clinical plans; median of 1.03 vs. 1.12. Mean doses to almost all organs at risk (OARs) were reduced in the automatic plans, with a median reduction of between 0.6 Gy and 1.9 Gy. In the blinded plan comparison, the automatic plans were the preferred plans or of equal quality as the clinical plans in 99% of the cases. In addition, plan delivery was excellent, with a mean gamma passing rate of 99.8%. Complete script-based plans were generated in 30-45 min; about four to ten times faster than manually made plans. CONCLUSION: The automatic plans had acceptable target coverage, lower doses to almost all OARs, more conformal dose distributions, and were predominantly preferred by the clinicians. Based on these results, our institution has implemented the script for clinical use.

A cross-sectional study examining the prevalence of cachexia and areas of unmet need in patients with cancer.

PURPOSE: The semantics of defining cancer cachexia over the last decade has resulted in uncertainty as to the prevalence. This has further hindered the recognition and subsequent treatment of this condition. Following the consensus definition for cancer cachexia in 2011, there is now a need to establish estimates of prevalence. Therefore, the primary aim of the present study was to assess the prevalence of cachexia in an unselected cancer population. A secondary aim was to assess patient-perceived need of attention to cachexia. METHODS: A cross-sectional study in hospital patients was undertaken. Key inclusion criteria were the following: age > 18 years, cancer diagnosis, and no surgery the preceding 24 h. Data on demographics, disease, performance status, symptoms, cachexia, and patients' perceived need of attention to weight loss and nutrition were registered. RESULTS: Data were available on 386 of 426 eligible patients. Median age (IQR) was 65 years (56-72), 214 (55%) were male and 302 (78%) had a performance status of 0-1 (Eastern Cooperative Oncology Group). Prevalence of cachexia (inpatients/outpatients) was 51/22%. Prevalence was highest in patients with gastrointestinal cancer (62/42%) and lung cancer (83/36%). There was no major difference in prevalence between patients with metastatic (55/24%) and localized disease (47/19%). Twenty percent of inpatients and 15% of outpatients wanted more attention to weight loss and nutrition. Cachexia (p < 0.001), symptoms of mood disorder (p < 0.001), and male gender (p < 0.01) were independently associated with increased need of attention. CONCLUSION: Cachexia is a prevalent condition, affecting both patients with localized and metastatic cancer. Clinical attention to the condition is a sizeable unmet need.

Is it possible to detect an improvement in cancer pain management? A comparison of two Norwegian cross-sectional studies conducted 5 years apart.

PURPOSE: Cancer pain (CP) management is challenging. In recent years, efforts were undertaken to achieve better CP management, e.g. clinical research, new treatment modalities, development of guidelines, education and focus on implementation. The aim of the present study was to compare the prevalence and characteristics of pain and breakthrough pain (BTP) between cross-sectional studies conducted in 2008 and 2014. It was hypothesized that an improvement in pain control would be observed the years in between. METHODS: Two cross-sectional studies were conducted where adult cancer patients answered questions from Brief Pain Inventory and the Alberta Breakthrough Pain Assessment Tool for cancer patients. Physicians reported socio-demographic and medical data. Regression models were applied for analysis. RESULTS: In total, 168 inpatients, 92 in 2008 and 76 in 2014, and 675 outpatients, 301 in 2008 and 374 in 2014, were included. The patient characteristics of the samples were comparable. Prevalence of CP among inpatients was 55 % in 2008 and 53 % in 2014, and among outpatients, 39 and 35 %, respectively. Inpatients reported average pain intensity (0-10 numerical rating scale, NRS) of 3.60 (standard deviation, SD 1.84) (2008) and 4.08 (SD 2.11) (2014); prevalence of BTP was 52 % (2008) and 41 % (2014). For outpatients, average pain intensity was 3.60 (SD 2.04) (2008) and 3.86 (SD 2.20) (2014); prevalence of BTP was 43 % (2008) and 37 % (2014). None of the differences were statistically significant. CONCLUSION: Unexpectedly, no improvement in pain control was observed. Efforts are still needed to improve cancer pain management.

Monte Carlo linear accelerator simulation of megavoltage photon beams: independent determination of initial beam parameters.

PURPOSE: To individually benchmark the incident electron parameters in a Monte Carlo model of an Elekta linear accelerator operating at 6 and 15 MV. The main objective is to establish a simplified but still precise benchmarking procedure that allows accurate dose calculations of advanced treatment techniques. METHODS: The EGSnrc Monte Carlo user codes BEAMnrc and DOSXYZnrc are used for photon beam simulations and dose calculations, respectively. A 5 × 5 cm(2) field is used to determine both the incident electron energy and the electron radial intensity. First, the electron energy is adjusted to match the calculated depth dose to the measured one. Second, the electron radial intensity is adjusted to make the calculated dose profile in the penumbrae region match the penumbrae measured by GafChromic EBT film. Finally, the mean angular spread of the incident electron beam is determined by matching calculated and measured cross-field profiles of large fields. The beam parameters are verified for various field sizes and shapes. RESULTS: The penumbrae measurements revealed a non-circular electron radial intensity distribution for the 6 MV beam, while a circular electron radial intensity distribution could best describe the 15 MV beam. These electron radial intensity distributions, given as the standard deviation of a Gaussian distribution, were found to be 0.25 mm (in-plane) and 1.0 mm (cross-plane) for the 6 MV beam and 0.5 mm (both in-plane and cross-plane) for the 15 MV beam. Introducing a small mean angular spread of the incident electron beam has a considerable impact on the lateral dose profiles of large fields. The mean angular spread was found to be 0.7° and 0.5° for the 6 and 15 MV beams, respectively. CONCLUSIONS: The incident electron beam parameters in a Monte Carlo model of a linear accelerator could be precisely and independently determined by the benchmarking procedure proposed. As the dose distribution in the penumbra region is insensitive to moderate changes in electron energy and angular spread, accurate penumbra measurements is feasible for benchmarking the electron radial intensity distribution. This parameter is particularly important for accurate dosimetry of mlc-shaped fields and small fields.

Training, validation, and clinical implementation of a deep-learning segmentation model for radiotherapy of loco-regional breast cancer.

AIM: To train and validate a comprehensive deep-learning (DL) segmentation model for loco-regional breast cancer with the aim of clinical implementation. METHODS: DL segmentation models for 7 clinical target volumes (CTVs) and 11 organs at risk (OARs) were trained on 170 left-sided breast cancer cases from two radiotherapy centres in Norway. Another 30 patient cases were used for validation, which included the evaluation of Dice similarity coefficient and Hausdorff distance, qualitative scoring according to clinical usability, and relevant dosimetric parameters. The manual inter-observer variation (IOV) was also evaluated and served as a benchmark. Delineation of the target volumes followed the ESTRO guidelines. RESULTS: Based on the geometric similarity metrics, the model performed significantly better than IOV for most structures. Qualitatively, no or only minor corrections were required for 14% and 71% of the CTVs and 72% and 26% of the OARs, respectively. Major corrections were required for 15% of the CTVs and 2% of the OARs. The most frequent corrections occurred in the cranial and caudal parts of the structures. The dose coverage, based on D98 > 95%, was fulfilled for 100% and 89% of the breast and lymph node CTVs, respectively. No differences in OAR dose parameters were considered clinically relevant. The model was implemented in a commercial treatment planning system, which generates the structures in 1.5 min. CONCLUSION: Convincing results from the validation led to the decision of clinical implementation. The clinical use will be monitored regarding applicability, standardization and efficiency.

Explaining variation in cancer survival between 11 jurisdictions in the International Cancer Benchmarking Partnership: a primary care vignette survey.

OBJECTIVES: The International Cancer Benchmarking Partnership (ICBP) is a collaboration between 6 countries and 12 jurisdictions with similar primary care-led health services. This study investigates primary care physician (PCP) behaviour and systems that may contribute to the timeliness of investigating for cancer and subsequently, international survival differences. DESIGN: A validated survey administered to PCPs via the internet set out in two parts: direct questions on primary care structure and practice relating to cancer diagnosis, and clinical vignettes, assessing management of scenarios relating to the diagnosis of lung, colorectal or ovarian cancer. PARTICIPANTS: 2795 PCPs in 11 jurisdictions: New South Wales and Victoria (Australia), British Columbia, Manitoba, Ontario (Canada), England, Northern Ireland, Wales (UK), Denmark, Norway and Sweden. PRIMARY AND SECONDARY OUTCOME MEASURES: Analysis compared the cumulative proportion of PCPs in each jurisdiction opting to investigate or refer at each phase for each vignette with 1-year survival, and conditional 5-year survival rates for the relevant cancer and jurisdiction. Logistic regression was used to explore whether PCP characteristics or system differences in each jurisdiction affected the readiness to investigate. RESULTS: 4 of 5 vignettes showed a statistically significant correlation (p<0.05 or better) between readiness to investigate or refer to secondary care at the first phase of each vignette and cancer survival rates for that jurisdiction. No consistent associations were found between readiness to investigate and selected PCP demographics, practice or health system variables. CONCLUSIONS: We demonstrate a correlation between the readiness of PCPs to investigate symptoms indicative of cancer and cancer survival rates, one of the first possible explanations for the variation in cancer survival between ICBP countries. No specific health system features consistently explained these findings. Some jurisdictions may consider lowering thresholds for PCPs to investigate for cancer-either directly, or by specialist referral, to improve outcomes.

Superficial doses in breast cancer radiotherapy using conventional and IMRT techniques: a film-based phantom study.

BACKGROUND AND PURPOSE: Superficial doses in radiotherapy are affected by the treatment technique. The implications for breast cancer treatments were evaluated. MATERIAL AND METHODS: Four treatment techniques relevant for breast cancer irradiation were evaluated; tangential standard, tangential IMRT, 7-field IMRT (arc-like field arrangement) and hybrid IMRT (an IMRT plan mixed with non-modulated fields). Only 6MV photons were used. GafChromic EBT film was used for dose measurements at the surface, in the skin (0-5mm depth) and in the superficial parts of CTV (5-10mm depth) of an anthropomorphic thorax phantom. RESULTS: Only small differences in superficial doses were observed between tangential standard and tangential IMRT. Compared to the tangential standard plan, the surface and skin doses were reduced with the 7-field IMRT plan, on average by 20% and 5%, respectively, while hybrid IMRT reduced the surface and skin doses medially (by 44% and 8%, respectively) and increased the surface and skin dose laterally (by 40% and 15%, respectively). Minimum superficial CTV doses varied between regions, but were mainly between 90% and 95% of the target dose for all plans, only the hybrid IMRT plan resulted in a region with minimum dose below 90%. CONCLUSIONS: Compared to tangential irradiation, skin sparing was achieved by the 7-field IMRT plan. The minimum dose in the superficial parts of the CTV was below 95% of the target dose for all plans investigated.