ESTRO 2026 Congress report

 

ESTRO 2026 took place in Stockholm from May 15–19, 2026. For oligometastatic disease (OMD) enthusiasts like us, it was pure heaven! Over four days, we had the opportunity to hear results from many cutting-edge trials, ranging from oligometastatic prostate and breast cancer to gynaecological malignancies, as well as stereotactic body radiotherapy (SBRT) outcomes in organ-specific OMD. Here are some of my highlights so far.

 

The Fortress of Oligometastasis: Prostate Cancer

Several important trials in prostate cancer were presented at this year’s congress, further reinforcing its role as one of the hallmark disease sites in oligometastatic research. One of the most anticipated presentations was “Updated Clinical Outcomes and Post-hoc Analysis of Metastasis-Free Survival and Eugonadal MFS from the RADIOSA Randomised Phase II Trial,” presented by Giulia Marvaso. Following the publication of the primary results in The Lancet Oncology last year, which garnered considerable attention, the updated analysis demonstrated that in patients with hormone-sensitive oligorecurrent prostate cancer, the addition of 6 months of androgen deprivation therapy to SBRT improved long-term clinical progression-free survival and metastasis-free survival, while reducing the risk of metastatic progression by 61% compared with SBRT alone. Long-term follow-up also showed a 60% reduction in the risk of poly-metastatic progression and a meaningful delay in the development of castration resistance. However, as Dr. Marvaso emphasised during the presentation, these findings should still be interpreted in the context of a phase II study.

 

What About OMD in Gynaecological Cancers?

Gynaecological malignancies are often underrepresented in OMD basket trials. However, ESTRO 2026 featured several noteworthy presentations. The first was “Post-progression trajectory and survival in oligorecurrent, oligometastatic cervix cancer: Results from the international multicentre RetroCOSMOS study,” presented by Supriya Chopra. This international multi-institutional study included 26 centres and categorised recurrent cervical cancer into three groups: synchronous oligometastatic disease (Class A), metachronous oligometastatic disease (Class B), and oligorecurrent disease (Class C). Among 421 patients, 18.5% were Class A, 30.4% Class B, and 51.1% Class C. Across all groups, up to 70% received systemic therapy, nearly 80% underwent radiotherapy, and 37% received re-irradiation. Median post-progression survival was 71 months for Class A, 38.4 months for Class B, and 49.5 months for Class C. The overall survival results are eagerly awaited. Another important presentation was “Toxicity Profile of SBRT After Bevacizumab in Oligometastatic Ovarian Cancer: A New Perspective for Radiation Oncologists?”, presented by Gabriella Macchia. This subgroup analysis of the MITO RT3/RAD study evaluated patients with oligorecurrent ovarian cancer treated with SBRT within 1 to 12 months after bevacizumab. Forty-one patients with 68 lesions were included. SBRT doses ranged from 20 Gy in 1 fraction to 50 Gy in 5 fractions, with a median PTV of 33 cc. Acute toxicity occurred in 19.5% of patients, all grade 2 or lower. One patient developed grade 2 late intestinal sub-occlusion, while no fistulas or bleeding events were observed. These findings suggest that SBRT administered at least one month after bevacizumab is safe in this setting.

 

Single-fraction SBRT for Lung Oligometastases

The concept of OMD is shaped not only by the primary tumour type, but also by the metastatic site itself. In this context, Neil Wallace presented the abstract “Single-fraction SABR for primary NSCLC and lung oligometastases: a pooled analysis of 1687 patients.” This study evaluated 1687 patients from the US National Cancer Database treated between 2006 and 2021 with single-fraction SABR doses ranging from 26–34 Gy. Among the cohort, 487 patients had pulmonary oligometastases. One- and two-year local control, progression-free survival, and overall survival rates were 95% and 90%, 47% and 32%, and 90% and 75%, respectively. Patients with colorectal cancer metastases demonstrated poorer local control compared with other histologies. Grade ≥2 toxicity was reported in 7.8% of patients, while grade ≥3 toxicity occurred in only 1.8%. During the discussion, it was also emphasised that the median tumour size in the pulmonary metastasis cohort was 13 mm. Overall, single-fraction SABR appears both feasible and highly effective in carefully selected patients.

 

Melek Tugce Yilmaz Aslan, MD

Hacettepe University Faculty of Medicine

Department of Radiation Oncology

Ankara, Turkiye

melektugceyilmaz@gmail.com / X: @mtugceyilmaz