Abstract Merkel cell carcinoma (MCC) is a rare malignancy with an annual incidence in Germany of 5.2 per million for men and 3.8 per million for women, predominantly affecting sun-exposed areas in older adults. Despite a frequently unfavorable prognosis, outcomes are multifactorial and depend on tumor site, disease stage, performance status, patient age, sex, and immune competence. The current standard of care prescribes surgical resection followed by adjuvant radiotherapy of the tumor bed, ideally initiated within 8 weeks after surgery to optimize clinical outcomes. In case of lymph node involvement, lymph node dissection and/or radiotherapy of the involved nodal basin are recommended. Furthermore, new evidence supports the effectiveness of shorter radiotherapy approaches, with moderate hypofractionated or even ultrahypofractionated schedules serving as effective options for certain patients, particularly those with frailty or comorbidities, or when it is clinically necessary to minimize the treatment burden. In cases of inoperability, refusal of surgery, or significant frailty, definitive local radiotherapy can achieve sufficient disease control. The synergistic potential of combining immunotherapy with radiation in advanced cases remains a key area for ongoing research.

Die Strahlentherapie ist eine etablierte Behandlungsmodalität der malignen Non-Hodgkin-Lymphome. Allerdings erfordert die zunehmende Komplexität der Behandlungssituationen eine präzise Indikationsstellung und -durchführung. Im vorliegenden Übersichtsartikel werden moderne radioonkologische Therapiestrategien vorgestellt. Es erfolgte eine selektive Literaturrecherche zur strahlentherapeutischen Behandlung maligner Non-Hodgkin-Lymphome mit Fokus auf das diffus großzellige B‑Zell-Lymphom, Marginalzonenlymphom und follikuläre Lymphom. Hierbei wurden relevante Studien sowie die deutsche S3-Leitlinienposition identifiziert und diskutiert. Indolente Lymphome können in frühen Stadien mittels einer Strahlentherapie kurativ behandelt werden. In sorgsam ausgewählten Behandlungsfällen sind Dosisdeeskalationen möglich, werden jedoch gemäß deutscher S3-Leitlinie nicht empfohlen. Bei aggressiven Non-Hodgkin-Lymphomen findet eine konsolidierende Radiotherapie meist im Anschluss an die Systemtherapie statt, um Regionen mit erhöhtem Rezidivrisiko zu adressieren. Besonders Patient*innen mit in der Positronenemissionstomographie (PET-)positiven Restbefunden sollen nachbestrahlt werden. Innovationen wie der Einsatz der Radiotherapie vor oder nach chimärer Antigen-Rezeptor-T-Zell-Therapie und die beginnende Implementierung der online-adaptiven Radiotherapie werden die Behandlungslandschaft in Zukunft erweitern.

Abstract Hodgkin lymphoma (HL) is a B‐cell‐derived malignancy often affecting young adults. Allocation into risk groups is based on staging with positron emission tomography and computed tomography (PET/CT) and the presence or absence of risk factors. Standard treatment for early‐stage favorable classic HL (cHL) consists of two cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD), followed by 20 Gy involved‐site radiotherapy (IS‐RT). Two cycles of escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (eBEACOPP) or a procarbazine‐free eBEACOPP variant plus two cycles of ABVD, followed by 30 Gy IS‐RT in the case of PET/CT positivity and no further treatment in the case of PET/CT negativity after chemotherapy should be considered in patients with early‐stage unfavorable cHL ≤ 60 years. If a less intensive approach is preferred and in individuals > 60 years, four cycles of A(B)VD followed by 30 Gy IS‐RT can be given. In advanced cHL, brentuximab vedotin, etoposide, cyclophosphamide, doxorubicin, dacarbazine, and dexamethasone (BrECADD) for four (in the case of PET/CT negativity after two cycles) or six cycles (in the case of PET/CT positivity after two cycles), followed by PET/CT‐guided 30 Gy IS‐RT should be considered in patients ≤ 60 years. Six cycles of nivolumab and AVD (N‐AVD) followed by PET/CT‐guided 30 Gy IS‐RT represents a less intensive alternative for younger patients and the preferred approach for patients > 60 years. Patients with cHL recurrence should receive checkpoint inhibitor‐containing salvage treatment followed by high‐dose chemotherapy and autologous stem cell transplantation if eligible. Treatment of nodular lymphocyte‐predominant HL differs from cHL in some situations and may contain an anti‐CD20 antibody. This guideline aims at providing recommendations for diagnosis, staging, treatment, and follow‐up of HL.

PURPOSE: Total neoadjuvant therapy (TNT) has demonstrated superior oncologic outcomes and improved organ preservation in randomized trials for locally advanced rectal cancer (LARC). This study aimed to assess the real-world implementation of TNT in clinical routine and identify barriers to its application. METHODS: This retrospective, multicenter cohort study analyzed 111 patients with LARC treated between February 2021 and May 2024 across three certified colorectal cancer centers in Germany. Patients were stratified into TNT and non-TNT groups according to their neoadjuvant treatment modality. Primary endpoints included treatment adherence, disease-free survival (DFS), postoperative morbidity, and documented reasons for omitting TNT. Outcomes were compared with benchmark protocols from established TNT trials. RESULTS: Despite fulfilling guideline criteria, only 23 of 111 patients (20%) received TNT. Main barriers to TNT included advanced age, comorbidities, and patient refusal. The 1-year DFS rate was 96% in the TNT group and 94% in the non-TNT group. Severe low anterior resection syndrome (LARS) occurred in 9% of TNT patients compared to 22% in the non-TNT group. Postoperative complication rates were similar across both groups. While TNT was associated with favorable trends in disease control and functional outcomes, statistical significance was not reached. CONCLUSION: There is a notable discrepancy between clinical guideline recommendations and real-world TNT implementation in LARC. Addressing patient-specific barriers and adopting standardized, risk-adapted treatment decision frameworks may improve clinical integration of TNT, particularly in older and comorbid populations.

Musculoskeletal disorders, particularly tendinitis and bursitis, are major contributors to global disability and healthcare burden. Low-dose radiotherapy (LDRT) has emerged as a promising treatment for refractory cases, demonstrating anti-inflammatory and anti-proliferative effects, especially in inflammatory conditions. However, the lack of standardized treatment volumes hampers reproducibility, radiation safety, and broader clinical adoption. To address this gap, an international panel of experts applied the Delphi method to develop consensus-based target volumes for LDRT in common indications such as shoulder bursitis, lateral elbow tendinitis, trochanteric pain syndrome, achilles tendinitis, and plantar fasciitis. Utilizing a standardized CT-based homunculus, target volumes were delineated in a 3D Cartesian coordinate system to enable precise definition of gross tumor volume (GTV), clinical target volume (CTV), and planning target volume (PTV). Additionally, associated ICD-10 codes were defined to facilitate clinical documentation, billing, and future research. This structured approach provides a foundation for consistent treatment protocols, improved radiation protection, and future prospective trials to refine LDRT application in benign musculoskeletal conditions.

Abstract Background Re-irradiation (re-RT) has gained popularity in the treatment of recurrent or progressive glioblastoma (rGBM) after first-line treatment. However, uncertainties regarding optimal treatment dose, fraction size and target volume definition remain. In this multicenter analysis of the Western German Cancer Center (WTZ), we analyze prognostic factors for patients treated with re-RT for rGBM with different fraction regimens. Methods We analyzed patients with rGBM (CNS-WHO °4, IDH-wildtype) who received re-RT after standard first-line treatment (±salvage resection/chemotherapy) between 01/2010 and 12/2021. Clinical, histopathological, and radiological data were evaluated to identify prognostic factors influencing event-free and overall survival, as well as treatment tolerability. Results We identified 118 patients of whom 87 received normofractionated (1.8-2 Gy/fx) re-RT with a mean dose of 40.8 Gy using a mean GTV-PTV margin of 8.8 mm. 31 patients were treated with moderate hypofractionation (2.4-3.5 Gy/fx) up to a mean dose of 36 Gy with a mean GTV-PTV margin of 4.1 mm. Propensity score weighting was used to compensate prognostic factors between these two cohorts. Re-resection classification (no, STR, GTR, p < 0.0001), age at diagnosis (p = 0.0082), unifocal vs. multifocal progression (p = 0.021) and time between first and second RT (p = 0.0109) were identified as significant prognostic factors using stepwise parameter selection. The propensity score weighted survival was 8.8 months for normofractionation and 9.9 months for hypofractionation (p = 0.63). Conclusion Age at initial diagnosis, progression pattern and time between first and second RT are prognostic for patients undergoing re-irradiation. No significant survival difference between normofractionated and hypofractionated approaches was detected, which should be further investigated.

PURPOSE:Low-dose radiation therapy (LDRT) is a minimally invasive treatment option for pain management in selected patients with osteoarthritis (OA). However, standardized and internationally accepted target volume definitions are still lacking. METHODS AND MATERIALS:An international expert consortium of 15 institutions from Europe and the United States conducted a Delphi consensus process to define joint-specific target volumes based on the 3-dimensional (3D) concept of the clinical target volume (CTV). A standardized computed tomography data set ("homunculus") was used by all participants to ensure uniform anatomical reference for target volume delineation. RESULTS:Target volume definition includes inflammatory and OA-specific pathological features such as joint effusion, cysts, and subchondral sclerosis. The CTV encompasses the joint capsule and varies in its cranio-caudal extent among individual patients. Using joint-specific isocenter definitions-such as the midpoint between the femoral condyles for the knee joint-the 3D boundaries of the CTV can be determined. This approach enables anatomically precise delineation of the target volume, ensuring inclusion of inflammation-relevant structures while excluding uninvolved bone and soft tissue. CONCLUSIONS:This international consensus statement provides practical guidance for a standardized 3D target volume definition in the radiation therapy of OA. Accurate knowledge of joint anatomy and pathology, combined with precise target volume delineation and careful consideration of the clinical context, such as symptom distribution and the pattern of joint involvement, may support more consistent LDRT treatment planning for OA. These target volume definitions also provide a structured basis for future clinical studies and further clinical validation.