CANTO-RT: One of the Largest Prospective Multicenter Cohort of Early Breast Cancer Patients Treated with Radiotherapy including Full DICOM RT Data

Essential requirements for reporting radiation therapy in breast cancer clinical trials: An international multi-disciplinary consensus endorsed by the European Society for Radiotherapy and Oncology (ESTRO)

The European Society for Radiotherapy and Oncology (ESTRO) has advocated the establishment of guidelines to optimise precision radiotherapy (RT) in conjunction with contemporary therapeutics for cancer care. Quality assurance in RT (QART) plays a pivotal role in influencing treatment outcomes. Clinical trials incorporating QART protocols have demonstrated improved survival rates with minimal associated toxicity. Nonetheless, in routine clinical practice, there can be variability in the indications for RT, dosage, fractionation, and treatment planning, leading to uncertainty. In pivotal trials reporting outcomes of systemic therapy for breast cancer, there is limited information available regarding RT, and the potential interaction between modern systemic therapy and RT remains largely uncharted. This article is grounded in a consensus recommendation endorsed by ESTRO, formulated by international breast cancer experts. The consensus was reached through a modified Delphi process and was presented at an international meeting convened in Florence, Italy, in June 2023. These recommendations are regarded as both optimal and essential standards, with the latter aiming to define the minimum requirements. A template for a case report form (CRF) has been devised, which can be utilised by all clinical breast cancer trials involving RT. Optimal requirements include adherence to predefined RT planning protocols and centralised QART. Essential requirements aim to reduce variations and deviations from the guidelines in RT, even when RT is not the primary focus of the trial. These recommendations underscore the significance of implementing these practices in both clinical trials and daily clinical routines to generate high-quality data.

CANTO skin: Evaluation of skin toxicity risk factors in patients treated for breast cancer

Skin reaction is a common toxicity during oncology management, especially followed during the radiotherapy. Its assessment and understanding of the factors influencing its occurrence, is a major issue in the management of patients treated for an early breast cancer (BC). We evaluated 8561 patients during their overall management for a BC. We focus on specific skin toxicities: erythema, fibrosis, telangiectasia and changes of skin colour. These toxicities were assessed at the baseline defined as 0-3-6 (M0), 12 (M12), 36 (M36) and 60 (M60) months. The prevalence of toxicities of interest varied over time, so at M0, 30.4% of patients had erythema while 17.7% of patients had fibrosis. At M60, the prevalence of erythema was 2%, while fibrosis remained stable at about 19%. After adjustments, at M0, there was a significant association between the onset of cutaneous erythema and obesity, the presence of axillary dissection, the type of surgery and the tumour phenotype RH+/HER2+. Concerning fibrosis, a significant association was found, at M12, with the age of the patient, obesity, Charlson score and type of surgery. Concerning the modification of skin colour at M12, we find a link between the age of the patient, obesity, tobacco consumption and alcohol consumption. The prevention of this toxicity is a major issue for the quality of life. Our results allow us to understand the risk of developing skin toxicity in a patient, depending on her intrinsic, tumour or therapeutic characteristics and to implement adapted means of prevention and monitoring.

End-to-end framework for automated collection of large multicentre radiotherapy datasets demonstrated in a Danish Breast Cancer Group cohort

Large Digital Imaging and Communications in Medicine (DICOM) datasets are key to support research and the development of machine learning technology in radiotherapy (RT). However, the tools for multi-centre data collection, curation and standardisation are not readily available. Automated batch DICOM export solutions were demonstrated for a multicentre setup. A Python solution, Collaborative DICOM analysis for RT (CORDIAL-RT) was developed for curation, standardisation, and analysis of the collected data. The setup was demonstrated in the DBCG RT-Nation study, where 86% (n = 7748) of treatments in the inclusion period were collected and quality assured, supporting the applicability of the end-to-end framework.

Radiation-induced lung injury after breast cancer treatment: incidence in the CANTO-RT cohort and associated clinical and dosimetric risk factors

Purpose

Radiation-induced lung injury (RILI) is strongly associated with various clinical conditions and dosimetric parameters. Former studies have led to reducing radiotherapy (RT) doses to the lung and have favored the discontinuation of tamoxifen during RT. However, the monocentric design and variability of dosimetric parameters chosen have limited further improvement. The aim of our study was to assess the incidence of RILI in current practice and to determine clinical and dosimetric risk factors associated with RILI occurrence.

Material and methods

Data from 3 out of the 10 top recruiting centers in CANTO-RT, a subset of the CANTO prospective longitudinal cohort (NCT01993498), were retrospectively analyzed for RILI occurrence. This cohort, which recruited invasive cT0-3 cN0-3 M0 breast cancer patients from 2012 to 2018, prospectively recorded the occurrence of adverse events by questionnaires and medical visits at the end of, and up to 60 months after treatment. RILI adverse events were defined in all patients by the association of clinical symptoms and compatible medical imaging.

Results

RILI was found in 38/1565 (2.4%) patients. Grade II RILI represented 15/38 events (39%) and grade III or IV 2/38 events (6%). There were no grade V events. The most frequently used technique for treatment was 3D conformational RT (96%). In univariable analyses, we confirmed the association of RILI occurrence with pulmonary medical history, absence of cardiovascular disease medical history, high pT and pN, chemotherapy use, nodal RT. All dosimetric parameters were highly correlated and had close predictive value. In the multivariable analysis adjusted for chemotherapy use and nodal involvement, pulmonary medical history (OR=3.05, p<0.01) and high V30 Gy (OR=1.06, p=0.04) remained statistically significant risk factors for RILI occurrence. V30 Gy >15% was significantly associated with RILI occurrence in a multivariable analysis (OR=3.07, p=0.03).

Conclusion

Our study confirms the pulmonary safety of breast 3D RT in CANTO-RT. Further analyses with modern radiation therapy techniques such as IMRT are needed. Our results argue in favor of a dose constraint to the ipsilateral lung using V30 Gy not exceeding 15%, especially in patients presenting pulmonary medical history. Pulmonary disease records should be taken into account for RT planning.