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Background Partial breast irradiation (PBI) is standard of care in low-risk breast cancer patients after breast-conserving surgery (BCS). Pre-operative PBI can result in tumor downstaging and more precise target definition possibly resulting in less treatment-related toxicity. This study aims to assess the pathologic complete response (pCR) rate one year after MR-guided single-dose pre-operative PBI in low-risk breast cancer patients. Methods The ABLATIVE-2 trial is a multicenter prospective single-arm trial using single-dose ablative PBI in low-risk breast cancer patients. Patients ≥ 50 years with non-lobular invasive breast cancer ≤ 2 cm, grade 1 or 2, estrogen receptor-positive, HER2-negative, and tumor-negative sentinel node procedure are eligible. A total of 100 patients will be enrolled. PBI treatment planning will be performed using a radiotherapy planning CT and -MRI in treatment position. The treatment delivery will take place on a conventional or MR-guided linear accelerator. The prescribed radiotherapy dose is a single dose of 20 Gy to the tumor, and 15 Gy to the 2 cm of breast tissue surrounding the tumor. Follow-up MRIs, scheduled at baseline, 2 weeks, 3, 6, 9, and 12 months after PBI, are combined with liquid biopsies to identify biomarkers for pCR prediction. BCS will be performed 12 months after radiotherapy or after 6 months, if MRI does not show a radiologic complete response. The primary endpoint is the pCR rate after PBI. Secondary endpoints are radiologic response, toxicity, quality of life, cosmetic outcome, patient distress, oncological outcomes, and the evaluation of biomarkers in liquid biopsies and tumor tissue. Patients will be followed up to 10 years after radiation therapy. Discussion This trial will investigate the pathological tumor response after pre-operative single-dose PBI after 12 months in patients with low-risk breast cancer. In comparison with previous trial outcomes, a longer interval between PBI and BCS of 12 months is expected to increase the pCR rate of 42% after 6–8 months. In addition, response monitoring using MRI and biomarkers will help to predict pCR. Accurate pCR prediction will allow omission of surgery in future patients. Trial registration The trial was registered prospectively on April 28th 2022 at clinicaltrials.gov (NCT05350722).

Lateral lymph nodes in low, locally advanced, rectal cancer have proven implications for local recurrence rates, which increase drastically in the presence of persistently enlarged lateral lymph nodes. These clinical implications warrant a thorough understanding of lateral nodal disease with awareness and knowledge from all three specialties involved – radiology, radiation oncology, and surgery – to ensure proper treatment. Relevant literature for each specialty, including all current guidelines and perspectives, were examined. Variations in definitions and treatment paradigms were evaluated. There is still no consensus for the standardized treatment of lateral nodal disease. Each discipline works according to their own available evidence, but relevant data are scarce. Current international guidelines and standard recommendations for the diagnostics and treatment of lateral lymph nodes are lacking. This results in differing perspectives and interpretations between the disciplines which can lead to challenging communication in an area where multidisciplinary collaboration is essential. This review addresses this by presenting the current evidence, perspectives and practices of each specialty and makes suggestions for each phase of the diagnostic and treatment process for patients with lateral nodal disease. By doing this, steps are taken toward achieving international consensus, and multidisciplinary collaboration.

BACKGROUND: Radiolabeled prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT) has shown superior diagnostic accuracy to conventional imaging for the detection of prostate cancer deposits . Consequently, clinical management changes have been reported in patients with biochemical recurrence (BCR) of disease after robot-assisted radical prostatectomy (RARP). We hypothesized that, due to the exclusion of patients with metastatic disease on PSMA-PET/CT, those who underwent local salvage radiation therapy (SRT) after restaging PSMA-PET/CT for BCR may have better oncological outcomes than patients who underwent "blind" SRT.OBJECTIVE: To compare the oncological outcome of a patient cohort that underwent PSMA-PET imaging prior to SRT with that of a patient cohort that did not have PSMA-PET imaging before SRT.DESIGN, SETTING, AND PARTICIPANTS: We included 610 patients who underwent SRT, of whom 298 underwent PSMA-PET/CT prior to SRT and 312 did not. No additional hormonal therapy was prescribed.OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: To compare both cohorts, case-control matching was performed, using the prostate-specific antigen (PSA) value at the initiation of SRT, pathological grade group, pathological T stage, surgical margin status, and biochemical persistence after RARP as matching variables. The outcome variable was biochemical progression at 1 yr after SRT, defined as either a rise of PSA ≥0.2 ng/ml above the nadir after SRT or the start of additional treatment.RESULTS AND LIMITATIONS: After case-control matching, 216 patients were matched in both cohorts (108 patients per cohort). In the patient cohort without PSMA-PET/CT prior to SRT, of 108 patients, 23 (21%) had biochemical progression of disease at 1 yr after SRT, compared with nine (8%) who underwent restaging PSMA-PET/CT prior to SRT (p = 0.007).CONCLUSIONS: PSMA-PET/CT is found to be associated with an improved oncological outcome in patients who undergo SRT for BCR after RARP.PATIENT SUMMARY: Performing prostate-specific membrane antigen positron emission tomography/computed tomography imaging in patients with biochemical recurrence of disease after robot-assisted radical prostatectomy, before initiating salvage radiation therapy, resulted in improved short-term oncological outcomes.

BACKGROUND AND PURPOSE: Neoadjuvant chemoradiotherapy (nCRT) is used in locally recurrent rectal cancer (LRRC) to increase chances of a radical surgical resection. Delineation in LRRC is hampered by complex disease presentation and limited clinical exposure. Within the PelvEx II trial, evaluating the benefit of chemotherapy preceding nCRT for LRRC, a delineation guideline was developed by an expert LRRC team.MATERIALS AND METHODS: Eight radiation oncologists, from Dutch and Swedish expert centres, participated in two meetings, delineating GTV and CTV in six cases. Regions at-risk for re-recurrence or irradical resection were identified by eleven expert surgeons and one expert radiologist. Target volumes were evaluated multidisciplinary. Inter-observer variation was analysed.RESULTS: Inter-observer variation in delineation of LRRC appeared large. Multidisciplinary evaluation per case is beneficial in determining target volumes. The following consensus regarding target volumes was reached. GTV should encompass all tumour, including extension into OAR if applicable. If the tumour is in fibrosis, GTV should encompass the entire fibrotic area. Only if tumour can clearly be distinguished from fibrosis, GTV may be reduced, as long as the entire fibrotic area is covered by the CTV. CTV is GTV with a 1 cm margin and should encompass all at-risk regions for irradical resection or re-recurrence. CTV should not be adjusted towards other organs. Multifocal recurrences should be encompassed in one CTV. Elective nodal delineation is only advised in radiotherapy-naïve patients.CONCLUSION: This study provides a first consensus-based delineation guideline for LRRC. Analyses of re-recurrences is needed to understand disease behaviour and to optimize delineation guidelines accordingly.

Purpose The European Organisation for Research and Treatment of Cancer conducted a randomized trial investigating the role of radiotherapy (RT) after local excision (LE) of ductal carcinoma-in-situ (DCIS) of the breast. We analyzed the efficacy of RT with 10 years follow-up on both the overall risk of local recurrence (LR) and related to clinical, histologic, and treatment factors. Patients and Methods After complete LE, women with DCIS were randomly assigned to no further treatment or RT (50 Gy). One thousand ten women with mostly (71%) mammographically detected DCIS were included. The median follow-up was 10.5 years. Results The 10-year LR-free rate was 74% in the group treated with LE alone compared with 85% in the women treated by LE plus RT (log-rank P < .0001; hazard ratio [HR] = 0.53). The risk of DCIS and invasive LR was reduced by 48% (P = .0011) and 42% (P = .0065) respectively. Both groups had similar low risks of metastases and death. At multivariate analysis, factors significantly associated with an increased LR risk were young age (≤ 40 years; HR = 1.89), symptomatic detection (HR = 1.55), intermediately or poorly differentiated DCIS (as opposed to well-differentiated DCIS; HR = 1.85 and HR = 1.61 respectively), cribriform or solid growth pattern (as opposed to clinging/micropapillary subtypes; HR = 2.39 and HR = 2.25 respectively), doubtful margins (HR = 1.84), and treatment by LE alone (HR = 1.82). The effect of RT was homogeneous across all assessed risk factors. Conclusion With long-term follow-up, RT after LE for DCIS continued to reduce the risk of LR, with a 47% reduction at 10 years. All patient subgroups benefited from RT.