The use of FDG-PET to target tumors by radiotherapy

EANM/SNMMI practice guideline for [18F]FDG PET/CT external beam radiotherapy treatment planning in uterine cervical cancer v1.0

PURPOSE

The aim of this EANM / SNMMI Practice Guideline with ESTRO endorsement is to provide general information and specific considerations about [18F]FDG PET/CT in advanced uterine cervical cancer for external beam radiotherapy planning with emphasis on staging and target definition, mostly in FIGO stages IB3-IVA and IVB, treated with curative intention.

METHODS

Guidelines from related fields, relevant literature and leading experts have been consulted during the development of this guideline. As this field is rapidly evolving, this guideline cannot be seen as definitive, nor is it a summary of all existing protocols. Local variations should be taken into consideration when applying this guideline.

CONCLUSION

The background, common clinical indications, qualifications and responsibilities of personnel, procedure / specifications of the examination, documentation / reporting and equipment specifications, quality control and radiation safety in imaging is discussed with an emphasis on the multidisciplinary approach.

[18F]FDG-PET or PET/CT in the evaluation of pelvic and para-aortic lymph nodes in patients with locally advanced cervical cancer: A systematic review of the literature

PURPOSE

Imaging is essential in detecting lymph node metastases for radiotherapy treatment planning in locally advanced cervical cancer (LACC). There are not many data on the performance of [¹⁸F]FDG-PET(CT) in showing lymph node metastases in LACC. We pooled sensitivity and specificity of [¹⁸F]FDG-PET(CT) for detecting pelvic and/or para-aortic lymph node metastases in patients with LACC. Also, the positive and negative posttest probabilities at high and low levels of prevalence were determined.

METHODS

MEDLINE and EMBASE searches were performed and quality characteristics assessed. Logit-sensitivity and logit-specificity estimates with corresponding standard errors were calculated. Summary estimates of sensitivity and specificity with corresponding 95% confidence intervals (CIs) were calculated by anti-logit transformation. Positive and negative likelihood ratios (LRs) were calculated from the mean logit-sensitivity and mean logit-specificity and the corresponding standard errors. The posttest probabilities were determined by Bayesian approach.

RESULTS

Twelve studies were included with a total of 778 patients aged 10-85 years. For pelvic nodes, summary estimates of sensitivity, specificity, LR+ and LR- were: 0.88 (95%CI: 0.40-0.99), 0.93 (95%CI: 0.85-0.97), 11.90 (95%CI: 5.32-26.62) and 0.13 (95%CI: 0.01-1.08). At the lowest prevalence of 0.15 the positive predictive value (PPV) and negative predictive value (NPV) were 0.68 and 0.98, at the highest prevalence of 0.65, 0.96 and 0.81. For the para-aortic nodes, the summary estimates of sensitivity, specificity LR+ and LR- were: 0.40 (95%CI: 0.18-0.66), 0.93 (95%CI: 0.91-0.95), 6.08 (95%CI: 2.90-12.78) and 0.64 (95%CI: 0.42-0.99), respectively. At the lowest prevalence of 0.17 the PPV and NPV were 0.55 and 0.88, at the highest prevalence of 0.50, 0.86 and 0.61.

CONCLUSION

The PPV and NPV of [¹⁸F]FDG-PET(CT) showing lymph node metastases in patients with LACC improves with higher prevalence. Prevalence and predictive values should be taken into account when determining therapeutic strategies based on [¹⁸F]FDG-PET(CT).

PET/MRI-guided GTV delineation during radiotherapy planning in patients with squamous cell carcinoma of the tongue

Purpose

The aim of the study was to evaluate the usefulness and accuracy of 18-fluorine-labeled fluorodeoxyglucose (PET) and magnetic resonance imaging (MRI) hybrid in gross tumor volume (GTV) delineation during radiotherapy planning in patients with carcinoma of the tongue.

Methods

Ten patients with squamous cell carcinoma (SCC) of the tongue underwent computed tomography (CT) and PET/MRI examination. The GTV for primary tumor and lymph nodes (nGTV) were defined on CT (GTV-CT) and compared to GTVs obtained from PET (GTV-PET) and MRI (GTV-MRI) images. Two methods of GTV determination were used: visual interpretation of CT, PET (GTV-PET_vis) and MRI images and quantitative automatic method (Syngovia, Siemens) based on a chosen threshold value (20%, 30%, 40%, 50%) of standardized uptake values (SUV_max) from PET examination (GTV-PET_20%, GTV-PET_30%, etc.). Statistical analysis of differences in GTV values obtained from CT, PET and MRI studies was performed. GTV-CT was used as a reference.

Results

In all, 80% of GTV-MRI and 40% of GTV-PET_vis were larger than GTV-CT. Respectively, 20% of GTV-MRI and 60% of GTV-PET_vis were smaller than GTV-CT. Taking into account all threshold measurements, 70% of volumes were smaller than GTV-CT. GTV-PET_30% were the most closely related volumes to GTV-CT from all threshold methods in 50% of patients. GTV-PET_vis generated the most similar volumes in relation to GTV-CT from all PET measurements. Statistical analysis confirmed those results. Compared to nGTV-CT, 70% of nGTV-MRI and 20% of nGTV-PET_vis were larger. The remaining nGTV-MRI and nGTV-PET_vis measurements were smaller than nGTV-CT. Measurements of all thresholds nGTVs were smaller than nGTV-CTV in 52.5% of cases. nGTV-PET_20% were the most closely related volumes to nGTV-CT in 40% of the cases. Statistical analysis showed that nGTV-PET_20% (p = 0.0468), nGTV-PET_vis (p = 0.0166), and nGTV-PET_50% (p = 0.0166) diverge significantly from nGTV-CT results. nGTV-MRI (p = 0.1141), nGTV-PET_30% (p = 0.2845), and nGTV-PET_40% (p = 0.5076) were significantly related with nGTV-CT.

Conclusion

Combination of PET/MRI provides more information during target tumor mass delineation in radiotherapy planning of patients with SCC of the tongue than other standard imaging methods. The most frequently matching threshold value was 30% of SUV_max for primary tumor delineation and 30–40% of SUV_max for nGTV determination.

Electronic supplementary material

The online version of this article (10.1007/s00066-019-01480-3) contains supplementary material, which is available to authorized users.

The Path Toward PET-Guided Radiation Therapy for Glioblastoma in Laboratory Animals: A Mini Review

Glioblastoma is the most aggressive and malignant primary brain tumor in adults. Despite the current state-of-the-art treatment, which consists of maximal surgical resection followed by radiation therapy, concomitant, and adjuvant chemotherapy, progression remains rapid due to aggressive tumor characteristics. Several new therapeutic targets have been investigated using chemotherapeutics and targeted molecular drugs, however, the intrinsic resistance to induced cell death of brain cells impede the effectiveness of systemic therapies. Also, the unique immune environment of the central nervous system imposes challenges for immune-based therapeutics. Therefore, it is important to consider other approaches to treat these tumors. There is a well-known dose-response relationship for glioblastoma with increased survival with increasing doses, but this effect seems to cap around 60 Gy, due to increased toxicity to the normal brain. Currently, radiation treatment planning of glioblastoma patients relies on CT and MRI that does not visualize the heterogeneous nature of the tumor, and consequently, a homogenous dose is delivered to the entire tumor. Metabolic imaging, such as positron-emission tomography, allows to visualize the heterogeneous tumor environment. Using these metabolic imaging techniques, an approach called dose painting can be used to deliver a higher dose to the tumor regions with high malignancy and/or radiation resistance. Preclinical studies are required for evaluating the benefits of novel radiation treatment strategies, such as PET-based dose painting. The aim of this review is to give a brief overview of promising PET tracers that can be evaluated in laboratory animals to bridge the gap between PET-based dose painting in glioblastoma patients.

Inclusion of PET-CT into planning of primary or neoadjuvant chemoradiotherapy of esophageal cancer improves prognosis

BACKGROUND

PET-CT is widely used for both the staging and planning of primary or neoadjuvant chemoradiotherapy for esophageal cancer. Inclusion of PET-CT information into radiotherapy planning often leads to substantial modifications of the target volume. In the case of detection of distant metastases, it may also result in a switch to a palliative treatment approach. This spares patients from therapy-related toxicities that provide no clinical benefit. However, due to a lack of studies, it is currently unclear whether the advantages of PET-CT also translate into a measurable improvement in patient survival.

PATIENTS AND METHODS

A retrospective analysis assessed the survival data of 145 patients with esophageal carcinoma stages I (eight patients; 5%), II (45; 31%), III (79; 55%), IV (8; 5%) and unknown (5; 4%). Patients were treated between 1999 and 2014 either with primary chemoradiation (n = 101) or neoadjuvant chemoradiation at the Department of Radiation Oncology, University Medical Center Mainz, followed by transabdominal or transthoracic tumor resection (n = 44). Of the 145 patients, 64 (44%) had undergone PET-CT.

RESULTS

Univariate analysis showed the use of PET-CT to be associated with significantly longer local recurrence-free survival (p = 0.006) and tended to translate into a measurable improvement of overall survival (p = 0.071). Since more patients underwent surgery in the group planned using PET-CT (20% vs. 44%; p = 0.002), we carried out a multivariate Cox regression analysis to adjust for this possible confounding factor. Surgery (p = 0.042; HR 0.55; 95% confidence interval: 0.31-0.98) as well as the use of PET-CT (p = 0.048; HR 0.60; 95% confidence interval: 0.36-0.99) nearly halved the risk of local recurrence. It was only in the group of patients with PET-CT that a trend towards a shorter overall survival was evident in lymph node-positive patients (p = 0.16), whereas nodal stage did not impact on survival in patients staged without PET-CT (p = 0.97).

CONCLUSION

To the best of our knowledge these data suggest for the first time that the use of PET-CT in the framework of staging and planning of primary or neoadjuvant chemoradiotherapy for esophageal cancer has a favorable impact on patient survival.

Maximum standardized uptake value on FDG-PET predicts survival in stage I non-small cell lung cancer following carbon ion radiotherapy

The present study (University Hospital Medical Information Network study no. UMIN000003797) aimed to evaluate whether the maximum standardized uptake value (SUV_max) of pretreatment ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is prognostic factor for stage I non-small cell lung cancer (NSCLC) treated with carbon ion radiotherapy (C-ion RT). Patients treated between June 2010 and June 2013 at Gunma University Heavy Ion Medical Center (Maebashi, Japan) on a prospective protocol were included in the present study. Patients with T1a-b and T2a NSCLC were treated with C-ion RT at a dose of 52.8 Gy [relative biological effectiveness (RBE)] and 60.0 Gy (RBE), respectively, in four fractions. Prior to treatment, all patients underwent FDG-PET, in which the SUV_max of primary tumors was evaluated. Local control, progression-free survival (PFS), and overall survival (OS) were calculated. A total of 45 patients were analyzed and the median follow-up period was 28.9 months. The 2-year local control, PFS and OS rates for all patients were 93, 78 and 89%, respectively. The mean SUV_max of primary tumors was 5.5, and patients were divided into higher (≥5.5) and lower (<5.5) SUV_max groups. The 2-year PFS rates were 61 and 89% for the higher and lower SUV_max groups, respectively (P=0.01), and the 2-year OS rates for the higher and lower SUV_max groups were 76 and 96%, respectively (P=0.01). The higher SUV_max group exhibited a significantly worse PFS and OS compared with the lower SUV_max group; however, the SUV_max was not associated with the local control rate. In total, 2 patients (4%) experienced grade 2 or 3 radiation pneumonitis, with their symptoms improved through conservative treatment. No patients experienced any grade 4 or 5 toxicities. The results of the present study indicate that pretreatment SUV_max is a prognostic indicator for outcomes in patients with stage I NSCLC treated with C-ion RT.

Interobserver variability in clinical target volume delineation for primary mediastinal B-cell lymphoma

PURPOSE

The purpose of this study was to evaluate interobserver variability among radiation oncologists with experience in the field of lymphoma radiation therapy in the delineation of clinical target volume (CTV) in a challenging case of primary mediastinal B-cell lymphoma.

METHODS AND MATERIALS

Ten experienced radiation oncologists were invited to a 1-day contouring session. The case of a 56-year-old man with primary mediastinal B-cell lymphoma with complete metabolic response after chemotherapy was chosen as the sample for the study. A brief presentation of his clinical history was given, together with guidelines for contouring. The 10 CTVs obtained were then compared in terms of variation in total volume and in craniocaudal, laterolateral, and anteroposterior diameters. The CTV with the best Dice similarity coefficient (DSC) between the union of all 10 CTVs and the individual CTV was considered the reference CTV, and the DSC and the Hausdorff distance (HD) for each volume compared with the reference CTV were then calculated.

RESULTS

A significant variability was found in total volume (mean, 498.3 cm(3); range, 181.8-1003 cm(3)) and craniocaudal (median, 144.7 mm; range, 80.6-159 mm), laterolateral (median, 133.5 mm; range, 83.7-149.5 mm), and anteroposterior diameters (median, 136.2 mm; range, 84-150.5 mm). Analysis of the DSC and the HD showed a mean DSC of 0.53 (range, 0.31-0.74) and a mean HD of 6.4 cm (range, 1.8-14.8 cm).

CONCLUSIONS

Results of this study strongly indicate the need to develop and share appropriate contouring guidelines among experts and suggest the promotion of specific educational activities to improve radiation therapy quality in both clinical trials and routine clinical practice.

Use of Positron Emission Tomography/Computed Tomography in Radiation Treatment Planning for Lung Cancer

Radiotherapy (RT) plays an important role in the treatment of lung cancer. Accurate diagnosis and staging are crucial in the delivery of RT with curative intent. Target miss can be prevented by accurate determination of tumor contours during RT planning. Currently, tumor contours are determined manually by computed tomography (CT) during RT planning. This method leads to differences in delineation of tumor volume between users. Given the change in RT tools and methods due to rapidly developing technology, it is now more significant to accurately delineate the tumor tissue. F18 fluorodeoxyglucose positron emission tomography/CT (F18 FDG PET/CT) has been established as an accurate method in correctly staging and detecting tumor dissemination in lung cancer. Since it provides both anatomic and biologic information, F18 FDG PET decreases inter-user variability in tumor delineation. For instance, tumor volumes may be decreased as atelectasis and malignant tissue can be more accurately differentiated, as well as better evaluation of benign and malignant lymph nodes given the difference in FDG uptake. Using F18 FDG PET/CT, the radiation dose can be escalated without serious adverse effects in lung cancer. In this study, we evaluated the contribution of F18 FDG PET/CT for RT planning in lung cancer.

Biological imaging in clinical oncology: radiation therapy based on functional imaging

Radiation therapy is one of the most effective tools for cancer treatment. In recent years, intensity-modulated radiation therapy has become increasingly popular in that target dose-escalation can be done while sparing adjacent normal tissues. For this reason, the development of measures to pave the way for accurate target delineation is of great interest. With the integration of functional information obtained by biological imaging with radiotherapy, strategies using advanced biological imaging to visualize metabolic pathways and to improve therapeutic index and predict treatment response are discussed in this article.

Definitive, Preoperative, and Palliative Radiation Therapy of Esophageal Cancer

BACKGROUND

Long-term survival in patients with esophageal cancer remains dismal despite the recent improvements in surgery, the advances in radiotherapy (RT) technology, and the refinement of systemic treatments, including the advent of targeted therapies. Although surgery constitutes the treatment of choice for early-stage disease (stage I), a multimodal approach, including preoperative or definitive chemoradiotherapy (CRT) and perioperative chemotherapy, is commonly pursued in patients with locally advanced disease.

METHODS

A review of the literature was performed to assess the role of RT, alone or in combination with chemotherapy, in the management of esophageal cancer.

RESULTS

Evidence from large, randomized phase III trials and meta-analyses supports the application of perioperative chemotherapy alone or preoperative concurrent CRT in patients with lower esophageal and esophagogastric junction adenocarcinomas. Preoperative CRT but not preoperative chemotherapy alone is now routinely used in patients with locally advanced squamous cell carcinoma (SCC). Additionally, definitive CRT without surgery has also emerged as a valuable approach in the management of resectable esophageal SCC to avoid surgery-related morbidity and mortality, whereas salvage surgery is reserved for those with persistent disease. Furthermore, brachytherapy offers a valuable option in the palliative treatment of patients with locally advanced, unresponsive disease. Fluorodeoxyglucose-positron emission tomography (FDG-PET) can facilitate a more accurate treatment response assessment and patient selection. Finally, the development of modern RT techniques, such as intensity-modulated and image-guided RT as well as FDG-PET-based RT planning, could further increase the therapeutic ratio of CRT.

CONCLUSION

Altogether, CRT constitutes an important tool in the treatment armamentarium for esophageal cancer. Further optimization of CRT using modern technology and imaging, targeted therapies, and newer chemotherapeutic agents is a major challenge and should be the goal of future research and clinical trials.

Tumour delineation in oesophageal cancer - A prospective study of delineation in PET and CT with and without endoscopically placed clip markers

PURPOSE

The objective was to analyse the value of F-18-fluorodesoxyglucose (FDG)-positron emission tomography/computed tomography (PET/CT) for delineation of the Gross Tumour Volumes (GTVs) in primary radiotherapy of oesophageal cancer.

METHOD

20 consecutive and prospective patients (13 men, 7 women) underwent FDG-PET/CT for initial staging and radiation treatment planning. After endoscopy-guided clipping of the tumour another CT study was acquired. The CT and the FDG-PET/CT were registered with a rigid and a non-rigid registration algorithm to compare the overlap between GTV contours defined with the following methods: manual GTV definition in (1) the CT image of the FDG-PET/CT, (2) the PET image of the FDG-PET/CT, (3) the CT study based on endoscopic clips (CT clip), and (4) in the PET-data using different semi-automatic PET segmentation algorithms including a gradient-based algorithm. The absolute tumour volumes, tumour length in cranio-caudal direction, as well as the overlap with the reference volume (CT-clip) were compared for all lesions and separately for proximal/distal tumours.

RESULTS

In 6 of the patients, FDG-PET/CT discovered previously unknown tumour locations, which resulted in either altered target volumes (n=3) or altered intent of treatment from curative to palliative (n=3) by upstaging to stage IV. For tumour segmentation a large variability between all algorithms was found. For the absolute tumour volumes with CT-clip as reference, no single PET-based segmentation algorithm performed better compared to using the manual CT delineation alone. The best correlation was found between the CT-clip and the gradient based segmentation algorithm (PET-edge, R(2)=0.84) as well as the manual CT-delineation (CT-manual R(2)=0.89). Non-rigid registration between CT and image FDG-PET/CT did not decrease variability between segmentation methods compared to rigid registration statistically significant. For the analysis of tumour length no homogeneous correlation was found.

CONCLUSION

Whereas FDG-PET was highly relevant for staging purposes, CT imaging with clipping of the tumour extension remains the gold standard for GTV delineation.

Optimising delineation accuracy of tumours in PET for radiotherapy planning using blind deconvolution

Positron emission tomography (PET) imaging has been proven to be useful in radiotherapy planning for the determination of the metabolically active regions of tumours. Delineation of tumours, however, is a difficult task in part due to high noise levels and the partial volume effects originating mainly from the low camera resolution. The goal of this work is to study the effect of blind deconvolution on tumour volume estimation accuracy for different computer-aided contouring methods. The blind deconvolution estimates the point spread function (PSF) of the imaging system in an iterative manner in a way that the likelihood of the given image being the convolution output is maximised. In this way, the PSF of the imaging system does not need to be known. Data were obtained from a NEMA NU-2 IQ-based phantom with a GE DSTE-16 PET/CT scanner. The artificial tumour diameters were 13, 17, 22, 28 and 37 mm with a target/background ratio of 4:1. The tumours were delineated before and after blind deconvolution. Student's two-tailed paired t-test showed a significant decrease in volume estimation error (p < 0.001) when blind deconvolution was used in conjunction with computer-aided delineation methods. A manual delineation confirmation demonstrated an improvement from 26 to 16 % for the artificial tumour of size 37 mm while an improvement from 57 to 15 % was noted for the small tumour of 13 mm. Therefore, it can be concluded that blind deconvolution of reconstructed PET images may be used to increase tumour delineation accuracy.

Cancer biomarker discovery: current status and future perspectives

PURPOSE

Cancer is a multigene disease which arises as a result of mutational and epigenetic changes coupled with activation of complex signaling networks. The use of biomarkers for early cancer detection, staging and individualization of therapy might improve patient care. A few fundamental issues such as tumor heterogeneity, a highly dynamic nature of the intrinsic and extrinsic determinants of radio- and chemoresistance, along with the plasticity and diversity of cancer stem cells (CSC) make biomarker development a challenging task. In this review we outline the preclinical strategies of cancer biomarker discovery including genomic, proteomic, metabolomic and microRNomic profiling, comparative genome hybridization (CGH), single nucleotide polymorphism (SNP) analysis, high throughput screening (HTS) and next generation sequencing (NGS). Other promising approaches such as assessment of circulating tumor cells (CTC), analysis of CSC-specific markers and cell-free circulating tumor DNA (ctDNA) are also discussed.

CONCLUSIONS

The emergence of powerful proteomic and genomic technologies in conjunction with advanced bioinformatic tools allows the simultaneous analysis of thousands of biological molecules. These techniques yield the discovery of new tumor signatures, which are sensitive and specific enough for early cancer detection, for monitoring disease progression and for proper treatment selection, paving the way to individualized cancer treatment.

The role of radiotherapy in the multimodal management of esophageal cancer

Despite recent improvements in surgery and radiotherapy, and refinements of systemic treatment options, including incorporation of targeted agents, long-term survival remains poor for patients with esophageal cancer. While surgical resection alone constitutes the standard approach for early-stage disease (stage I), multimodality therapy, including perioperative chemotherapy and neoadjuvant or definitive chemoradiotherapy (CRT), are internationally accepted treatment options for patients with locally advanced disease. In lower esophageal and esophagogastric junction adenocarcinomas, data from large, randomized phase III trials and meta-analyses support the use of both perioperative chemotherapy alone or neoadjuvant concurrent CRT. In patients with locally advanced squamous cell carcinoma (SCC) of the esophagus, neoadjuvant CRT but not neoadjuvant chemotherapy alone is the preferred treatment approach. Definitive CRT without surgery has also emerged as a useful option for the treatment of resectable SCC of the esophagus, avoiding potential surgical morbidity and mortality, with salvage surgery reserved for those with persistent disease. Functional imaging modalities, such as PET-CT, may create new opportunities for a more adequate therapy response assessment and patient selection. Patients with SCC that show clinical response by PET-CT are considered to have a more favorable outcome, regardless of whether surgery will be performed or not. In nonresponding patients, salvage surgery improves survival, especially if complete resection is achieved. Recent technological advances in radiotherapy, such as intensity-modulated radiotherapy, image guided-radiotherapy and PET-CT-based radiotherapy planning, may further improve the therapeutic ratio of CRT. Moreover, the traditional backbone of CRT, platinum plus fluorouracil, may be supplanted by more modern and easier-to-administer regimens incorporating taxanes, irinotecan and targeted agents.

Multicenter evaluation of different target volume delineation concepts in pediatric Hodgkin's lymphoma. A case study

BACKGROUND AND PURPOSE

In pediatric Hodgkin's lymphoma (PHL) improvements in imaging and multiagent chemotherapy have allowed for a reduction in target volume. The involved-node (IN) concept is being tested in several treatment regimens for adult Hodgkin's lymphoma. So far there is no consensus on the definition of the IN. To improve the reproducibility of the IN, we tested a new involved-node-level (INL) concept, using defined anatomical boundaries as basis for target delineation. The aim was to evaluate the feasibility of IN and INL concepts for PHL in terms of interobserver variability.

PATIENTS AND METHODS

The INL concept was defined for the neck and mediastinum by the PHL Radiotherapy Group based on accepted concepts for solid tumors. Seven radiation oncologists from six European centers contoured neck and mediastinal clinical target volumes (CTVs) of 2 patients according to the IN and the new INL concepts. The median CTVs, coefficient of variation (COV), and general conformity index (CI) were assessed. The intraclass correlation coefficient (ICC) for reliability of delineations was calculated.

RESULTS

All observers agreed that INL is a feasible and practicable delineation concept resulting in stronger interobserver concordance than the IN (mediastinum CI(INL) = 0.39 vs. CI(IN) = 0.28, neck left CI(INL) = 0.33; CI(IN) = 0.18; neck right CI(INL) = 0.24, CI(IN) = 0.14). The COV showed less dispersion and the ICC indicated higher reliability of contouring for INL (ICC(INL) = 0.62, p < 0.05) as for IN (ICC(IN) = 0.40, p < 0.05).

CONCLUSION

INL is a practical and feasible alternative to IN resulting in more homogeneous target delineation, and it should be therefore considered as a future target volume concept in PHL.

Highly cited German research contributions to the fields of radiation oncology, biology, and physics: focus on collaboration and diversity

BACKGROUND AND PURPOSE

Tight budgets and increasing competition for research funding pose challenges for highly specialized medical disciplines such as radiation oncology. Therefore, a systematic review was performed of successfully completed research that had a high impact on clinical practice. These data might be helpful when preparing new projects.

METHODS

Different measures of impact, visibility, and quality of published research are available, each with its own pros and cons. For this study, the article citation rate was chosen (minimum 15 citations per year on average). Highly cited German contributions to the fields of radiation oncology, biology, and physics (published between 1990 and 2010) were identified from the Scopus database.

RESULTS

Between 1990 and 2010, 106 articles published in 44 scientific journals met the citation requirement. The median average of yearly citations was 21 (maximum 167, minimum 15). All articles with ≥ 40 citations per year were published between 2003 and 2009, consistent with the assumption that the citation rate gradually increases for up to 2 years after publication. Most citations per year were recorded for meta-analyses and randomized phase III trials, which typically were performed by collaborative groups.

CONCLUSION

A large variety of clinical radiotherapy, biology, and physics topics achieved high numbers of citations. However, areas such as quality of life and side effects, palliative radiotherapy, and radiotherapy for nonmalignant disorders were underrepresented. Efforts to increase their visibility might be warranted.

Intensity-modulated stereotactic radiotherapy for the treatment of medically inoperable patients with NSCLC stage I

The standard treatment for stage I non-small cell lung cancer (NSCLC) is lobectomy. However, a considerable number of patients are not eligible for standard lung surgery due to poor pulmonary function or comorbidities. We evaluated the efficacy and tolerability of intensity-modulated stereotactic radiotherapy (IMSRT) with moderate hypofractionation for these patients. Twelve patients were selected for IMSRT. 4D-CT planning was performed by gating CT-scanning positioning. The applied doses ranged between 10x4.5 Gy (80% ID) (N=1), 12x4.5 Gy (95% ID) (N=1) and 10x5.5 Gy (95% ID) (N=10). Long-term follow-up was performed including spirometry and CT for evaluation of local, locoregional and distant control. Even in patients with poor pulmonary function IMRST was safe and well tolerated. No severe acute adverse effects were observed. Estimated local control at 2 years was 90%. Moreover, IMSRT does not induce a significant deterioration of pulmonary function. IMRST is safe and feasible even for patients with very poor pulmonary function. The applied dose provides a high local control rate, although the biological equivalent dose (BED) is lower compared to the average of other SRT regimens. Therefore, IMRST may be an efficient alternative for all NSCLC stage I patients with contraindications to standard lobectomy especially in patients with small tumors in high-risk localisations.

Use of FDG-PET in Radiation Treatment Planning for Thoracic Cancers

Radiotherapy plays an important role in the treatment for thoracic cancers. Accurate diagnosis is essential to correctly perform curative radiotherapy. Tumor delineation is also important to prevent geographic misses in radiotherapy planning. Currently, planning is based on computed tomography (CT) imaging when radiation oncologists manually contour the tumor, and this practice often induces interobserver variability. F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) has been reported to enable accurate staging and detect tumor extension in several thoracic cancers, such as lung cancer and esophageal cancer. FDG-PET imaging has many potential advantages in radiotherapy planning for these cancers, because it can add biological information to conventional anatomical images and decrease the inter-observer variability. FDG-PET improves radiotherapy volume and enables dose escalation without causing severe side effects, especially in lung cancer patients. The main advantage of FDG-PET for esophageal cancer patients is the detection of unrecognized lymph node or distal metastases. However, automatic delineation by FDG-PET is still controversial in these tumors, despite the initial expectations. We will review the role of FDG-PET in radiotherapy for thoracic cancers, including lung cancer and esophageal cancer.

Postoperative versus definitive chemoradiation in early-stage anal cancer. Results of a matched-pair analysis

BACKGROUND AND PURPOSE

The goal of the present study was to comparatively assess the results of definitive chemoradiation (CRT) with or without previous macroscopically complete resection in patients with early-stage node-negative (T1-2 N0) anal carcinoma.

PATIENTS AND METHODS

A total of 20 patients with T1-2 N0 anal carcinoma who received radiotherapy (RT) with or without chemotherapy following incidental R0/1 tumor resection (S/CRT group) were selected. These were matched to 20 comparable patients who underwent definitive chemoradiation without previous surgery (CRT group). Major objectives of this analysis were treatment outcomes in terms of locoregional tumor control (LRC), overall survival (OS), colostomy-free survival, and toxicity.

RESULTS

Patients treated postoperatively received significantly lower RT doses (median 54.0 Gy vs. 59.7 Gy; p < 0.001) and less frequently concomitant chemotherapy than those treated definitely. The 5-year LRC and 5-year OS rates were 97.5% and 90.0%, respectively, without significant differences between the S/CRT and the CRT groups. The distribution of acute and late toxicities was comparable, and the 5-year colostomy-free survival was 95% in both groups.

CONCLUSION

This matched-pair comparison of incidental R0/1 resection plus dose-reduced CRT with standard definitive CRT of early-stage anal cancer shows similar treatment results. Thus, dose-reduced RT with or without chemotherapy may be considered in R0/1 resected patients with T1-2 N0 anal carcinoma.

Evidence for the use PET for radiation therapy planning in patients with cervical cancer: a systematic review

BACKGROUND AND OBJECTIVE

In recent years, the role of positron emission tomography (PET) in the staging and management of gynecological cancers has been increasing. The aim of this study was to systematically review the role of PET in radiotherapy planning and brachytherapy treatment optimization in patients with cervical cancer.

DESIGN AND SETTING

Systematic literature review.

METHODS

Systematic review of relevant literature addressing the utilization of PET and/or PET-computed tomography (CT) in external-beam radiotherapy planning and brachytherapy treatment optimization. We performed an extensive PubMed database search on 20 April 2011. Nineteen studies, including 759 patients, formed the basis of this systematic review.

RESULTS

PET/ PET-CT is the most sensitive imaging modality for detecting nodal metastases in patients with cervical cancer and has been shown to impact external-beam radiotherapy planning by modifying the treatment field and customizing the radiation dose. This particularly applies to detection of previously uncovered para-aortic and inguinal nodal metastases. Furthermore, PET/ PET-CT guided intensity-modulated radiation therapy (IMRT) allows delivery of higher doses of radiation to the primary tumor, if brachytherapy is unsuitable, and to grossly involved nodal disease while minimizing treatment-related toxicity. PET/ PET-CT based brachytherapy optimization allows improved tumor-volume dose distribution and detailed 3D dosimetric evaluation of risk organs. Sequential PET/ PET-CT imaging performed during the course of brachytherapy form the basis of “adaptive” brachytherapy in cervical cancer.

CONCLUSIONS

This review demonstrates the effectiveness of pretreatment PET/ PET-CT in cervical cancer patients treated by radiotherapy. Further prospective studies are required to define the group of patients who would benefit the most from this procedure.

Intensity-modulated arc therapy with cisplatin as neo-adjuvant treatment for primary irresectable cervical cancer. Toxicity, tumour response and outcome

PURPOSE

The goal of this work was to evaluate the feasibility and outcome of intensity-modulated arc therapy ± cisplatin (IMAT ± C) followed by hysterectomy for locally advanced cervical cancer.

PATIENTS AND METHODS

A total of 30 patients were included in the study. The primary tumour and PET-positive lymph node(s) received a simultaneous integrated boost. Four weeks after IMAT ± C treatment, response was evaluated. Resection consisted of hysterectomy with or without lymphadenectomy. Tumour response, acute and late radiation toxicity, postoperative morbidity and outcome were evaluated.

RESULTS

All hysterectomy specimens were macroscopically tumour-free with negative resection margins; pathological complete response was 40%. In 2 patients, one resected lymph node was positive. There was no excess in postoperative morbidity. Apart from two grade 3 hematologic toxicities, no grade 3 or 4 acute radiation toxicity was observed. No grade 3, 1 grade 4 (4%) intestinal, and 4 grade 3 (14%) urinary late toxicities were observed. The 2-year local and regional control rates were 96% and 100%, respectively. The 2-year distant control rate was 92%. Actuarial 2-year progression free survival rate was 89%. Actuarial 1- and 2-year overall survival rates were 96% and 91%, while 3-year overall survival was 84%.

CONCLUSION

Surgery after IMAT ± C is feasible with low postoperative morbidity and radiation toxicity. Local, regional, distant control and survival rates are promising.

Respiratory gated [18F]FDG PET/CT for target volume delineation in stereotactic radiation treatment of liver metastases

PURPOSE

The use of 4D-[(18)F]fluorodeoxyglucose (FDG) PET/CT in combination with respiratory gated magnet resonance imaging (MRI) in target volume definition for stereotactic radiation of liver metastases was investigated.

METHODS AND MATERIALS

A total of 18 patients received respiration gated FDG-PET/CT and MRI. Data were fused using a rigid co-registration algorithm. The quality of the co-registration was rated on a scale from 1 (excellent) to 5 (poor) for co-registration of MRI with gated PET and ungated PET. Gross tumor volume (GTV) was delineated in CT (GTV (CT)), MRI (GTV(MRI)), and PET (GTV(PET)). MRI- and PET-based GTVs were defined by three observers each. Interobserver variability was calculated for all patients as well as for subgroups with and without previous treatment of liver metastases. All GTVs were compared for all patients and separately for patients with previous local therapy. In addition, a semiautomatic segmentation algorithm was applied on the PET images.

RESULTS

Co-registration  between MR and PET images was rated with 3.3 in average when non-gated PET was used and improved significantly (p < 0.01) to 2.1 using gated PET. The average GTV(CT)  was 51.5 ml, GTV(MRI)  51.8 ml, and the average GTV(PET)  48.1 ml. Volumes delineated in MRI were 9.9% larger compared to those delineated in CT. Volumes delineated in PET were 13.8% larger than in MRI. The differences between the GTVs were more pronounced in patients with previous treatment. The GTVs defined in MRI showed an interobserver variability of 47.9% (84.1% with previous treatment and 26.2% without previous treatment). The PET-defined GTVs showed an interobserver variability of 21% regardless of previous treatment. Semiautomatic segmentation did not provide satisfying results.

CONCLUSION

FDG-PET can distinguish vital tumor tissue and scar tissue, and therefore alters the GTV especially in patients with previous local treatment. In addition, it reduces the interobserver variability significantly compared to MRI. However, respiratory gated PET is necessary for good co-registration of PET and MRI.

Application of metabolic PET imaging in radiation oncology

Positron emission tomography (PET) is a noninvasive imaging technique that provides functional or metabolic assessment of normal tissue or disease conditions and is playing an increasing role in cancer radiotherapy planning. (18)F-Fluorodeoxyglucose PET imaging (FDG-PET) is widely used in the clinic for tumor imaging due to increased glucose metabolism in most types of tumors; its role in radiotherapy management of various cancers is reviewed. In addition, other metabolic PET imaging agents at various stages of preclinical and clinical development are reviewed. These agents include radiolabeled amino acids such as methionine for detecting increased protein synthesis, radiolabeled choline for detecting increased membrane lipid synthesis, and radiolabeled acetate for detecting increased cytoplasmic lipid synthesis. The amino acid analogs choline and acetate are often more specific to tumor cells than FDG, so they may play an important role in differentiating cancers from benign conditions and in the diagnosis of cancers with either low FDG uptake or high background FDG uptake. PET imaging with FDG and other metabolic PET imaging agents is playing an increasing role in complementary radiotherapy planning.

A review of clinical trials of cetuximab combined with radiotherapy for non-small cell lung cancer

Treatment of non-small cell lung cancer (NSCLC) is challenging in many ways. One of the problems is disappointing local control rates in larger volume disease. Moreover, the likelihood of both nodal and distant spread increases with primary tumour (T-) stage. Many patients are elderly and have considerable comorbidity. Therefore, aggressive combined modality treatment might be contraindicated or poorly tolerated. In many cases with larger tumour volume, sufficiently high radiation doses can not be administered because the tolerance of surrounding normal tissues must be respected. Under such circumstances, simultaneous administration of radiosensitizing agents, which increase tumour cell kill, might improve the therapeutic ratio. If such agents have a favourable toxicity profile, even elderly patients might tolerate concomitant treatment. Based on sound preclinical evidence, several relatively small studies have examined radiotherapy (RT) with cetuximab in stage III NSCLC. Three different strategies were pursued: 1) RT plus cetuximab (2 studies), 2) induction chemotherapy followed by RT plus cetuximab (2 studies) and 3) concomitant RT and chemotherapy plus cetuximab (2 studies). Radiation doses were limited to 60-70 Gy. As a result of study design, in particular lack of randomised comparison between cetuximab and no cetuximab, the efficacy results are difficult to interpret. However, strategy 1) and 3) appear more promising than induction chemotherapy followed by RT and cetuximab. Toxicity and adverse events were more common when concomitant chemotherapy was given. Nevertheless, combined treatment appears feasible. The role of consolidation cetuximab after RT is uncertain. A large randomised phase III study of combined RT, chemotherapy and cetuximab has been initiated.

Salvage radiotherapy in patients with recurrent esophageal carcinoma

PURPOSE

The feasibility and effectiveness of radiotherapy in the management of recurrent esophageal carcinoma (REC) is reported.

PATIENTS AND METHODS

A consecutive cohort of 54 patients with rcT1-4, rcN0-1, or cM0 recurrent esophageal carcinoma (69% squamous cell carcinoma, 31% adenocarcinoma) was treated between 1988 and 2010. The initial treatment for these patients was definitive radiochemotherapy, surgery alone, or neoadjuvant radiochemotherapy + surgical resection in 8 (15%), 33 (61%), and 13 (24%) patients, respectively. The median time to recurrence from initial treatment was 19 months (range 4-79 months). The site of the recurrence was anastomotic or local, nodal, or both in 63%, 30%, and 7% of patients, respectively. Salvage radio(chemo)therapy was carried out with a median dose of 45 Gy (range 30-68 Gy).

RESULTS

Median follow-up time for surviving patients from the start of R(C)T was 38 months (range 10-105 months). Relief of symptoms was achieved in 19 of 28 symptomatic patients (68%). The median survival time was 12 months (95% confidence interval (CI) 7-17 months) and the median recurrence-free interval was 8 months (95% CI 4-12 months). The survival rates at 1, 2, and 3 years were 55 ± 7%, 29 ± 6%, and 19 ± 5%, respectively. The recurrence-free survival rates at 1, 2, and 3 years were 44 ± 7%, 22 ± 6%, and 15 ± 5%, respectively. A radiation dose ≥ 45 Gy and conformal RT were associated with a better prognosis.

CONCLUSION

RT is feasible and effective in the management of recurrent esophageal carcinoma, especially for relief of symptoms. Toxicity is in an acceptable range. The outcome of REC is poor; however, long-term survival of patients with recurrent esophageal carcinoma after radiochemotherapy might be possible, even with a previous history of radiotherapy in the initial treatment. If re-irradiation of esophageal carcinoma is contemplated, three-dimensional conformal techniques and a minimum total dose of 45 Gy are recommended.

PET-guided dose escalation tomotherapy in malignant pleural mesothelioma

PURPOSE

To test the feasibility of salvage radiotherapy using PET-guided helical tomotherapy in patients with progressive malignant pleural mesothelioma (MPM).

PATIENTS AND METHODS

A group of 12 consecutive MPM patients was treated with 56 Gy/25 fractions to the planning target volume (PTV); FDG-PET/CT simulation was always performed to include all positive lymph nodes and MPM infiltrations. Subsequently, a second group of 12 consecutive patients was treated with the same dose to the whole pleura adding a simultaneous integrated boost of 62.5 Gy to the FDG-PET/CT positive areas (BTV).

RESULTS

Good dosimetric results were obtained in both groups. No grade 3 (RTOG/EORTC) acute or late toxicities were reported in the first group, while 3 cases of grade 3 late pneumonitis were registered in the second group: the duration of symptoms was 2-10 weeks. Median overall survival was 8 months (1.2-50.5 months) and 20 months (4.3-33.8 months) from the beginning of radiotherapy, for groups I and II, respectively (p=0.19). A significant impact on local relapse from radiotherapy was seen (median time to local relapse: 8 vs 17 months; 1-year local relapse-free rate: 16% vs 81%, p=0.003).

CONCLUSIONS

The results of this pilot study support the planning of a phase III study of combined sequential chemoradiotherapy with dose escalation to BTV in patients not able to undergo resection.

Extrapulmonary small cell carcinoma: An indication for prophylactic cranial irradiation? A single center experience

BACKGROUND

Information about extrapulmonary small cell carcinoma (EPSCC) is limited and the role of prophylactic cranial irradiation (PCI) is unknown.

PATIENTS AND METHODS

Disease presentation and outcome of all EPSCC at our hospital between 1990 and 2009 were retrospectively analyzed.

RESULTS

Of 30 EPSCC, the male:female ratio was 58%:42%; 83% had a performance status of 0-2. Median age was 71 years (32-80). Seventeen (57%) had limited stage (LS), 13 (43%) extensive stage (ES). The location of the primary tumor was gastrointestinal (n = 8), unknown (6), gynecological (6), urogenital (5), and ear nose throat (5). Four (13%) developed brain metastases (2 ES, 2 LS). In ES, first line chemotherapy (CT) was given in 85%, mostly platinum-etoposide (64%). Response rate was 90%. In LS, CT and radiotherapy (RT) ± resection resulted in persistent remissions in 67% of patients. Median survival was 16 months (1-107 months), 18 months (1-107 months), and 9 months (0.4-25 months) for LS + ES, LS, and ES, respectively. Weight loss ≥5 % and ECOG performance status 3 + 4 were associated with poorer survival (p < 0.001 and p < 0.01, respectively).

CONCLUSION

The incidence of brain metastases was relatively low (13%). More studies are necessary, before routinely offering PCI to patients with EPSCC. Best survival outcomes in LS were achieved with multimodality treatment including CT and RT. Prognosis was poor in patients with ES.

Interobserver variability of clinical target volume delineation in supra-diaphragmatic Hodgkin's disease: a multi-institutional experience

BACKGROUND

To determine interobserver variability in clinical target volume (CTV) of supra-diaphragmatic Hodgkin's lymphoma.

MATERIALS AND METHODS

At the 2008 AIRO (Italian Society of Radiation Oncology) Meeting, the Radiation Oncology Department of Chieti proposed a multi-institutional contouring dummy-run of two cases of early stage supra-diaphragmatic Hodgkin's lymphoma after chemotherapy. Clinical history, diagnostics, and planning CT imaging were available on Chieti's radiotherapy website (www.radioterapia.unich.it). Participating centers were requested to delineate the CTV and submit it to the coordinating center. To quantify interobserver variability of CTV delineations, the total volume, craniocaudal, laterolateral, and anteroposterior diameters were calculated.

RESULTS

A total of 18 institutions for case A and 15 institutions for case B submitted the targets. Case A presented significant variability in total volume (range: 74.1-1,157.1 cc), craniocaudal (range: 6.5-22.5 cm; median: 16.25 cm), anteroposterior (range: 5.04-14.82 cm; median: 10.28 cm), and laterolateral diameters (range: 8.23-22.88 cm; median: 15.5 cm). Mean CTV was 464.8 cc (standard deviation: 280.5 cc). Case B presented significant variability in total volume (range: 341.8-1,662 cc), cranio-caudal (range: 8.0-28.5 cm; median: 23 cm), anteroposterior (range: 7.9-1.8 cm; median: 11.1 cm), and laterolateral diameters (range: 12.9-24.0 cm; median: 18.8 cm). Mean CTV was 926.0 cc (standard deviation: 445.7 cc).

CONCLUSION

This significant variability confirms the need to apply specific guidelines to improve contouring uniformity in Hodgkin's lymphoma.

New approach for treatment of vertebral metastases using intensity-modulated radiotherapy

PURPOSE

To perform aggressive radiotherapy for vertebral metastases. Using very steep dose gradients from intensity-modulated radiotherapy (IMRT), a protocol based on the concept of partial volume dose to the spinal cord was evaluated.

PATIENTS AND METHODS

50 patients with vertebral metastases were treated using IMRT. In previously unirradiated cases, where a prescribed dose of 80 Gy (BED10) was delivered, the constraint to the spinal cord should be less than 100 Gy (BED2). For previously irradiated cases, on the other hand, the dose is the same as in the previously unirradiated case; however, constraints for the spinal cord are a cumulative BED2 of less than 150 Gy, BED2 of less than 100 Gy in each instance, and a treatment gap of more than 6 months. There were 6 patients considered for a partial volume dose to the spinal cord. They all received higher BED2, ranging from 51-157 Gy of D1cc.

RESULTS

Among the 24 patients who survived longer than 1 year, there was 1 case of transient radiation myelitis. There were no other cases of spinal cord sequelae.

CONCLUSION

Based on the present results, we recommend a BED2 of 100 Gy or less at D1cc as a constraint for the spinal cord in previously unirradiated cases, and a cumulative BED2 of 150 Gy or less at D1cc in previously irradiated cases, when the interval was not shorter than 6 months and the BED2 for each session was 100 Gy or less. The prescribed BED10 of 80 Gy could be safely delivered to the vertebral lesions.