The aim of this study was to assess the association between radiological and histopathological response after neoadjuvant radiotherapy (nRT) in soft tissue sarcoma (STS), as well as the prognostic value of the different response evaluation methods on the oncological outcome. A retrospective cohort of patients with localized STS of the extremity and trunk wall, treated with nRT followed by resection were included. The radiological response was assessed by RECIST 1.1 (RECIST) and MR-adapted Choi (Choi), histopathologic response was evaluated according to the EORTC-STBSG recommendations. Oncological outcome parameters of interest were local recurrence-free survival (LRFS), disease metastases-free survival (DMFS), and overall survival (OS). For 107 patients, complete pre- and postoperative pathology and imaging datasets were available. Most tumors were high-grade (77%) and the most common histological subtypes were undifferentiated pleomorphic sarcoma/not otherwise specified (UPS/NOS, 40%), myxoid liposarcoma (MLS, 21%) and myxofibrosarcoma (MFS, 16%). When comparing RECIST to Choi, the response was differently categorized in 58%, with a higher response rate (CR + PR) with Choi. Radiological responders showed a significant lower median percentage of viable cells (RECIST p = .050, Choi p = .015) and necrosis (RECIST p < .001), and a higher median percentage of fibrosis (RECIST p = .005, Choi p = .008), compared to radiological non-responders (SD + PD). RECIST, Choi, fibrosis, and viable cells were not significantly associated with altered oncological outcome, more necrosis was associated with poorer OS (p = .038). RECIST, Choi and the EORTC-STBSG response score show incongruent results in response evaluation. The radiological response was significantly correlated with a lower percentage of viable cells and necrosis, but a higher percentage of fibrosis. Apart from necrosis, radiological nor other histopathological parameters were associated with oncologic outcomes.
Some aspects of the treatment protocol for breast cancer during pregnancy (PrBC) have not been thoroughly studied. This study provides clarity regarding the safety of the use of 125I-seeds as a localization technique for breast-conserving surgery in patients with PrBC.To calculate the exposure to the fetus of one 125I-seed implanted in a breast tumor, we developed a model accounting for the decaying 125I-source, time to surgery, and the declining distance between the 125I-seed and the fetus. The primary outcome was the maximum cumulative fetal dose of radiation at consecutive gestational ages (GA).The cumulative fetal dose remains below 1 mSv if a single 125I-seed is implanted at a GA of 26 weeks. After a GA of 26 weeks, the fetal dose can be at a maximum of 11.6 mSv. If surgery takes place within two weeks of implantation from a GA of 26 weeks, and one week above a GA of 32 weeks, the dose remains below 1 mSv.The use of 125I-seeds is safe in PrBC. The maximum fetal exposure remains well below the threshold of 100 mSv, and therefore, does not lead to an increased risk of fetal tissue damage. Still, we propose keeping the fetal dose as low as possible, preferably below 1 mSv.
Merkel cell carcinoma (MCC) is a cutaneous tumor with a high tendency to metastasize, and a significant proportion of patients have metastases at first presentation. This study aims to determine the value of baseline ultrasound (US) and 18 fluorodeoxyglucose-positron emission tomography/computed tomography (18 FDG-PET/CT) imaging in both patients with clinically localized MCC (Stage I/II) and patients who present with palpable lymph nodes (Stage III).This retrospective cohort included 135 MCC patients who underwent baseline US (with fine needle aspiration cytology (FNAC)) and/or FDG-PET/CT imaging between 2015 and 2021.Of the 104 patients with clinically localized disease, 48% were upstaged to Stage III and 3% to Stage IV by imaging or sentinel lymph node biopsy (SLNB). FDG-PET/CT imaging identified regional metastases in 23%, while US with FNAC identified regional metastases in 19%. SLNB was performed in 56 patients, of whom 57% were upstaged to Stage III. Of the 31 patients who presented with palpable lymph nodes, 16% were upstaged to Stage IV by FDG-PET/CT imaging.Baseline imaging frequently upstages Stage I/II MCC patients to Stage III, both by US and FDG-PET/CT, Stage IV disease is rarely identified. Patients who present with palpable nodes are frequently upstaged to Stage IV by FDG-PET/CT imaging.
<div>AbstractPurpose:<p>Gastrointestinal stromal tumors (GIST) commonly arise in different regions of the stomach and are driven by various mutations (most often in <i>KIT, PDGFRA</i>, and <i>SDHx</i>). We hypothesized that the anatomic location of gastric GIST is associated with unique genomic profiles and distinct driver mutations.</p>Experimental Design:<p>We compared <i>KIT</i> versus non-<i>KIT</i> status with tumor location within the National Cancer Database (NCDB) for 2,418 patients with primary gastric GIST. Additionally, we compiled an international cohort (TransAtlantic GIST Collaborative, TAGC) of 236 patients and reviewed sequencing results, cross-sectional imaging, and operative reports. Subgroup analyses were performed for tumors located proximally versus distally. Risk factors for <i>KIT</i> versus non-<i>KIT</i> tumors were identified using multivariate regression analysis. A random forest machine learning model was then developed to determine feature importance.</p>Results:<p>Within the NCDB cohort, non-<i>KIT</i> mutants dominated distal tumor locations (<i>P</i> < 0.03). Proximal GIST were almost exclusively <i>KIT</i> mutant (96%) in the TAGC cohort, whereas 100% of <i>PDGFRA</i> and <i>SDH</i>-mutant GIST occurred in the distal stomach. On multivariate regression analysis, tumor location was associated with <i>KIT</i> versus non-<i>KIT</i> mutations. Using random forest machine learning analysis, stomach location was the most important feature for predicting mutation status.</p>Conclusions:<p>We provide the first evidence that the mutational landscape of gastric GIST is related to tumor location. Proximal gastric GIST are overwhelmingly <i>KIT</i> mutant, irrespective of morphology or age, whereas distal tumors display non-<i>KIT</i> genomic diversity. Anatomic location of gastric GIST may therefore provide immediate guidance for clinical treatment decisions and selective confirmatory genomic testing when resources are limited.</p></div>
Poster: ECR 2017 / C-2823 / Mamaloc: magnetic marker localization for non-palpable breast cancer, a novel localization technology from the radiologists’ perspective. by: B. Schermers1, C. Loo 1, P. de Koekkoek1, C. A. H. Lange1, I. M. de Zwart1, A. Bruining1, J. van der Hage1, F. van Duijnhoven1, T. J. Ruers2; 1Amsterdam/NL, 2Enschede/NL
