ESTRO 2026 Congress Report
By the ESTRO Skin Focus Group
This report provides a summary of those presentations dedicated to skin cancer and soft-tissue sarcoma that were delivered at ESTRO 2026.
Of all 220 sessions at ESTRO 2026, three were dedicated to skin cancer and nine to soft-tissue sarcoma. The two symposia on skin cancer comprised six oral presentations, two proffered papers, two mini-oral presentations, two poster presentations, and twenty-six digital posters. The nine sessions focusing on soft-tissue sarcoma comprised one proffered paper presentation, one symposium, and seven poster sessions.
Soft-tissue sarcomas
At #ESTRO2026, the sarcoma track highlighted how precision radiotherapy is increasingly being tailored to histology, anatomy, and tumour biology.
The long-term update of the DOREMY trial by Jules Lansu et al. confirmed that dose de-escalation in myxoid liposarcoma remains highly effective. Preoperative radiation therapy with 36 Gy in 18 fractions achieved excellent 5-year local control (98%) with very limited severe late toxicity, reinforcing the exceptional radiosensitivity of this subtype and supporting reduced-dose strategies in selected patients.
Similarly, Siyer Roohani et al. presented important data from SU2C-SARC032 showing that reduced target volume margins in extremity and truncal soft-tissue sarcoma can safely maintain excellent local control. Using 3cm longitudinal and 1.5 cm radial CTV margins, only two local recurrences were observed after more than four years of follow-up, both occurring in-field, while rates of fibrosis, oedema, and fractures remained low.
A different approach to treatment intensification was explored by Bradley Eckelmann et al., who reported prospective phase II results of dose-escalated hypofractionated radiation therapy for inoperable soft-tissue sarcoma. Treatment with 54 Gy in 6 fractions, including MRI-guided delivery in half of patients, achieved high local control with limited acute toxicity, although distant progression and late grade 3 toxicity remain important challenges.
Advanced imaging also featured prominently. Benoît Allignet et al. demonstrated the feasibility of a rapid multiparametric quantitative MRI workflow capable of assessing tumour hypoxia without contrast injection. Biomarkers such as rOEF and SvO2 correlated strongly with pathological response after neoadjuvant radiation therapy, opening the door to biologically guided adaptation strategies in soft-tissue sarcoma.
In rare bone and soft-tissue tumours, Mariam Ebrahim and colleagues presented real-world outcomes from The Christie Proton Centre for non-skull base chordoma and chondrosarcoma. Proton beam therapy achieved excellent long-term local control and survival outcomes, with no grade 4–5 acute toxicity observed.
Finally, Kevin Liu and colleagues reported prospective phase II data on preoperative intensity-modulated proton therapy with simultaneous integrated boost for retroperitoneal sarcoma. Selective dose escalation to high-risk posterior margins resulted in a low 4-year local failure rate despite frequent positive-margin resections, further supporting the role of highly conformal proton strategies in retroperitoneal disease.
An excellent complementary symposium, chaired by Beate Timmermann and Enrico Pozzo, focused on “Optimising radiotherapy for soft-tissue sarcomas: Bridging clinical evidence and technological progress.” The session covered the current role of RT in retroperitoneal sarcoma (Lisette Wiltink), definitive strategies for unresectable disease including hypofractionation and particle therapy (Carlo Greco), SBRT for oligometastatic sarcoma (Siyer Roohani), and the emerging role of daily adaptive radiotherapy in sarcoma treatment (Mateusz Spalek).
Overall, the ESTRO 2026 sarcoma sessions reflected a clear movement toward smarter, more individualised radiotherapy — through dose de-escalation where biology allows it, selective intensification where risk remains high, and increasing integration of advanced imaging, adaptive workflows and proton therapy.
Skin cancer
Prof Roland Kaufmann, Frankfurt, Germany and Prof. Agata Rembielak, Manchester, United Kingdom, co-chaired the 3rd Joint ESTRO-EADO Symposium: “Immuno-radiotherapy in the personalised oncology era: a promising strategy for cutaneous SCC”. The multi-professional speakers panel included Prof. Christoffer Gerbhardt, Hamburg, Germany; Prof Luca Tagliaferri, Rome, Italy; Dr. Romaana Mir, of Mount Vernon Cancer Centre, United Kingdom; and Dr. Vassilis Vassiolou, BOCOC, Cyprus.
Prof Kaufmann opened the joint EADO-ESTRO Symposium with a compelling argument against routine radiation delivery alongside immunotherapy in advanced cutaneous squamous cell carcinoma (cSCC). He outlined the dermatologist's goals of cSCC management as being primary prevention through the treatment of actinic keratosis and early detection of invasive disease. The clinical evidence supporting routine radio-immunotherapy was described as sparse, as the synergistic impact from the combination of treatment modalities is not yet fully understood. Randomised data are difficult to obtain in this often-older patient population, and hence the optimal sequence and dose of radiation remain unresolved. Prof Tagliaferri opened the counter-pro argument by highlighting that technical advances in radiation delivery facilitate curative intent treatment in sensitive anatomical sites. The advent of Cemiplimab immunotherapy was celebrated, and in circumstances of tumour progression during Cemiplimab treatment, Professor Tagliaferri described short-course palliative dose radiation-immuno boost as an important strategy to enable recapture of response to immunotherapy.
Elizabeth Barnes and Kurian Joseph, Canada, co-chaired the Meet the Expert ESTRO Guideline Session on Merkel cell carcinoma. Brendan McCann, Glasgow, Scotland, guideline primary author, introduced the first ESTRO Clinical Practice Guideline in this rare tumour type with Mateusz Spalek, Poland, and Romaana Mir presenting a classical and non-classical case. A management vote for a patient with non-classical stage IIIB Merkel cell carcinoma with tumour nodules at the lower leg and no distant metastases was split with 40% of the audience favouring radical dose radiation to the lower leg, 46% immunotherapy, and 13% palliative dose radiation – illustrating the clinical uncertainty and the need to balance local control against the risk of distant metastases.
Kurian Joseph, Alberta, Canada, detailed late recurrences following Merkel cell carcinoma from an international cohort of 949 patients. 48/949 (5.1%) patients developed a local recurrence; half (21/48) developed local recurrence at a median of 24 months. Isolated lymph node recurrence occurred in 8 patients at a median of 47 months, and isolated distant recurrence was seen in 6 patients at a median of 45.5 months. Among the 20 patients with both lymph node and distant recurrences, lymph node disease preceded distant spread by a median of 17 months. The cascade pattern of spread of local, lymph node, to distant sites is observed and is consistent with that in the literature. Joseph remarked that extended surveillance beyond three years is recommended to capture these late relapses.
Magdalena Stankiewicz, Gliwice, Poland, presented highlights in skin brachytherapy. High dose rate contact interventional radiotherapy is an effective treatment for keratinocyte carcinoma (KC) (cSCC and basal cell carcinoma). Flat contact HDR applicators may be suboptimal in curved anatomical regions, and Stankiewicz discussed the Nautilus Effect, a curvature-dependent asymmetry of dose distribution. This dosimetric study demonstrated that increased curvature produced asymmetric dosimetric effects with a strong correlation between curvature and normalised mean dose R2 = 0.98. The preliminary findings support the development of personalised 3D printed applicators to facilitate homogenous dose distribution to the target volume.
Panagiotis Balermpas et al., Zurich, Switzerland, reported outcomes from Flash-Skin I: A Phase I Clinical Study of LINAC-based Electron Flash Radiotherapy for Palliative Treatment of Malignant Melanoma Skin Lesions. Flash-Skin I delivered two fractions of 9Gy eFlash-RT over seven days (dose rate 216Gy/s), followed by one 9Gy fraction of conventional electron radiotherapy (dose rate 0.17Gy/s). The primary endpoint was dose-limiting skin toxicity at six weeks. At median follow-up of 427 days, there were no grade III dose-limiting events with complete, partial, and stable responses seen. Electron flash radiotherapy delivered with a modified C-arm linac was deemed safe with limited toxicity.
Romaana Mir presented “Skin Cosmesis Assessment Tools for Patients with Keratinocyte Carcinoma: A Systematic Review on behalf of the ESTRO Skin and Soft Tissue Focus Group”. KCs are highly prevalent and rarely impact mortality. Post-treatment skin cosmesis, described as how good the skin looks, is paramount as the sequelae of treatment are visible and impact social functioning. There is no consensus on reporting post-treatment cosmesis, and this lack of consensus precludes standardised cosmesis comparisons between treatments. The systematic review identified eighty-five records, comprising 14953 patients treated between 1955 and 2022 for 16752 lesions: 12064 basal cell carcinomas (BCC), 3525 cutaneous squamous cell carcinomas (cSCC), 639 other, and 524 not specified. Most studies were retrospective with heterogeneous assessment methods, limiting comparability. A planned collaboration between the ESTRO Focus Group and GEC‑ESTRO will aim to define standardised skin cosmesis evaluation tools for this area of unmet need.
Thirty-six skin cancer digital posters were selected for presentation at ESTRO 2026, including optimal strategies for local control of uveal melanoma, single institution outcomes following adjuvant radiation in high-risk cSCC, combination radiation modalities in cSCC, impact of radiation on skin of colour, and clinical outcomes following the management of melanoma brain metastases.
Dr Romaana Mir, MB ChB, MSc, FRCP, FRCR, MD(Res)
Mount Vernon Cancer Centre
Northwood, UK
Secretary ESTRO Skin and Soft Tissue Focus Group
romaana.mir@nhs.net
Dr Siyer Roohani, MD
Department of Radiation Oncology
Hubertus Wald Tumorzentrum
Universitäres Cancer Centre Hamburg, Germany
s.roohani@uke.de
Member of the ESTRO Skin Focus Group