Session Item

The use of re-irradiation is increasing, propelled by the introduction of new radiation therapy (RT) techniques. However, high-level evidence to guide clinical practice is scarce. Thus, we investigated international patterns of care of re-irradiation (reRT), presenting hereby the thoracic indications.

We conducted an online survey from March to September 2022. The survey was endorsed by the European Organisation for Radiotherapy and Oncology (ESTRO) and the European Organisation for Research and Treatment of Cancer (EORTC) and distributed to radiation/clinical oncologists, as well as on social media (e.g., Twitter). The survey was split into five sections according to anatomical regions. Participants answered the sections matching their clinical focus. Each section included 14 multiple-choice questions, covering distinct parts of the reRT workflow, including indications, planning & delivery techniques, and follow-up. Percentages in the following refer to the total number of participants answering each question.

In total, 371 physicians responded to the survey, of which 221 concerning thoracic reRT. The most common cancer types treated with re-irradiation were locally recurrent lung cancer (86%), lymph node metastases (79.2%) or lung/pleural metastases (71%) (Fig 1A).
Persistent grade 3 or higher toxicity (76.8%) from previous RT and an ECOG performance status of >2 (65.5%) were the most common conditions precluding thoracic reRT (Fig. 1B). For 52% of the respondents, the minimum interval after which they would consider re-irradiation was 6-12 months (Fig. 2A). In the postoperative setting, 33.6% of the respondents would not deliver reRT, whereas 35.5% would after R1-resection and 35.7% only in case of gross residual disease. ReRT was intended to achieve local control (89.6%) or to alleviate symptoms (69.2%). For treatment planning, most participants co-register CT (89.5%) and/or PET (87.2%) with the planning CT from initial RT (69.9%), using rigid image registration (70.6%). Assuming (partial) recovery of organs at risk (OAR) from RT may allow for higher cumulative doses to be accepted. For the chest wall, 54.4% of the participants allowed higher cumulative doses, while 48.2% and 47.7% did so for lungs and spinal cord, respectively (Fig. 2B).
VMAT (87.3%) and/or SBRT (79.6%) are most commonly utilized to deliver re-irradiation. CBCT is used by 92.2% of respondents for position verification.
After reRT, 61.1% state that patients are followed-up primarily by a radiation oncologist.

Thoracic reRT is applied in patients with locally recurrent and metastatic cancer to achieve different treatment goals, mostly using modern, conformal techniques or SBRT. Clinical practice diverges regarding patient selection, the minimum interval after primary RT, and acceptable OAR dose constraints. Thus, prospective investigation to guide harmonization of decision making and treatment management would be desirable.