Background: The total marrow and lymph node irradiation (TMLI) target includes the bones, spleen, and lymph node chains, with the latter being the most challenging structures to contour. We evaluated the impact of introducing internal contour guidelines to reduce the inter- and intraobserver lymph node delineation variability in TMLI treatments. Methods: A total of 10 patients were randomly selected from our database of 104 TMLI patients so as to evaluate the guidelines’ efficacy. The lymph node clinical target volume (CTV_LN) was recontoured according to the guidelines (CTV_LN_GL_RO1) and compared to the historical guidelines (CTV_LN_Old). Both topological (i.e., Dice similarity coefficient (DSC)) and dosimetric (i.e., V95 (the volume receiving 95% of the prescription dose) metrics were calculated for all paired contours. Results: The mean DSCs were 0.82 ± 0.09, 0.97 ± 0.01, and 0.98 ± 0.02, respectively, for CTV_LN_Old vs. CTV_LN_GL_RO1, and between the inter- and intraobserver contours following the guidelines. Correspondingly, the mean CTV_LN-V95 dose differences were 4.8 ± 4.7%, 0.03 ± 0.5%, and 0.1 ± 0.1%. Conclusions: The guidelines reduced the CTV_LN contour variability. The high target coverage agreement revealed that historical CTV-to-planning-target-volume margins were safe, even if a relatively low DSC was observed.

Aims: We report the mature toxicity data of a phase II non-randomized trial on the use of SBRT for lung and liver oligometastases. Methods: Oligometastatic patients from breast cancer were treated with SBRT for up to five lung and/or liver lesions. Inclusion criteria were: age > 18 years, ECOG 0–2, diagnosis of breast cancer, less than five lung/liver lesions (with a maximum diameter <5 cm), metastatic disease confined to the lungs and liver or extrapulmonary or extrahepatic disease stable or responding to systemic therapy. Various dose–fractionation schedules were used. Then, a 4D-CT scan and FDG-CTPET were acquired for simulation and fused for target definition. Results: From 2015 to 2021, 64 patients and a total of 90 lesions were irradiated. Treatment was well tolerated, with no G 3–4 toxicities. No grade ≥3 toxicities were registered and the coprimary endpoint of the study was met. Median follow-up was 19.4 months (range 2.6–73.1). Conclusions: The co-primary endpoint of this phase II trial was met, showing excellent tolerability of SBRT for lung and liver oligometastatic in breast cancer patients. Until efficacy data will mature with longer follow-up, SBRT should be regarded as an opportunity for oligometastatic breast cancer patients.

Background: Stereotactic ablative radiotherapy (SABR) is emerging as a potential local treatment option for oligometastatic RCC. This study aims to evaluate the efficacy of SABR in patients with oligorecurrent RCC. Methods: A total of 50 patients with histologically confirmed RCC underwent SABR for oligorecurrence between 2006 and 2022. Eligible patients had up to five extracranial metastases and were systemic treatment-naïve at the time of irradiation. The primary endpoints of the analysis were overall survival (OS), local control (LC), distant metastasis–free survival (DMFS), and time to systemic therapy initiation. Results: The median OS was not reached, with 1- and 3-year OS rates of 93.8% and 77.5%, respectively. LC rates at one and three years were 95.8% and 86.5%, respectively. The median time to systemic therapy initiation was 63.8 months, and the median DMFS was 17.9 months, with one- and three-year rates of 63.4% and 36.6%, respectively. Multiple metastases were a negative predictive factor for DMFS (HR 2.39, p = 0.023), whereas lung metastases were associated with a more favorable outcome (HR 0.38, p = 0.011). Conclusions: SABR offers a valuable treatment option for oligometastatic RCC, demonstrating significant potential for achieving long-term disease control and delaying the need for systemic therapy.