Background: Recently, an increasing international interest has arisen in using morbidity and mortality rates to monitor the quality of hospital cares (1, 2). Many hospitals have integrated the morbidity and mortality review (MMR) meetings into their governance processes, by making them mandatory and more accountable for taking corrective action (3-5).

Quality of radiotherapy (RT) delivery is highly operator dependent. The operator is a team of professionals including radiation oncologists, planning dosimetrists, physicists and technicians. Because of this complex, multi-step process, there is margin for error, which may affect outcomes and toxicity. Some deviations may have minimal effects on outcome, while others may have a profound effect and compromise long-term results. For the morbidity after RT, MMR is identified as one of the most adapted process to highlight whether and how these meetings provide assurance within the organizations' governance processes in radiation departments.

In France, many teams have not reached a formalized procedure for a systematic MMR. Furthermore, implementation of MMR in RT departments is very heterogeneous and not always meets the criteria defined by the Health Authorities (HAS) (6).

Systemic analysis conducted during the MMR is a comprehensive analysis of the situation, taking into account all technical and human elements. The diagnosis and type of morbidity depends on the irradiated volume, the dose delivered to the organ at risk and the individual radiosensitivity.

Follow-up after RT is important to evaluate outcome results and late toxicity. In general, late effects consist of tissue fibrosis and vascular damage, which can result in cosmetic and functional deterioration. Some of the radiation-induced sequelea may require particular management including hospitalization (lung fibrosis, gastro-intestinal and genito-urinary toxicities,..), while for other ones, only local treatments are needed (mucosal toxicity, skin fibrosis…). The challenge for clinicians in the frame of the MMR is to make sure that there is no controversy about the delivered RT quality and investigate other potential causes such as particular intrinsic radiosensitivity of the patient for a given standard treatment.

The study consist of a prospective registration in a dedicated database (PROUST) of severe radiation toxicity that aims to implement MMR procedure in the French radiotherapy departments.

Inclusion Criteria:

• Age ≥ 18 years
• Patients who received RT alone or associated to other anti-cancer treatments
• Significant and durable toxicity grade > 3 whatever the organs concerned by radiation exposure
• Completion of baseline clinical and dosimetric data collection
• Patients with no psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
• Signed informed consent to participate in the study must be obtained from patients after they have been fully informed on the nature and interest to investigated radiosensitivity by the investigator.

Exclusion Criteria:

• No formal MMR meeting in the center where the patient has been treated
• No clinical and/or dosimetric available data
• No quality of life questionnaire completion whatever the cause
• Patients who do not agree to have at least one of the planed biologic tests, namely, skin biopsy and blood samples.
• Absence of affiliation to National French social security system
• Patient deprived of freedom or under legal protection (guardianship,curatorship)

Datas are own by Assistance Publique - Hôpitaux de Paris, please contact sponsor for further information