Development of a Scoring Instrument for Identification of Pneumonitis in Older Lung Cancer Patients After Radiotherapy (POLCAR): A Protocol for a Prospective Trial

<b>Background/Objectives</b>: Pneumonitis caused by radiotherapy for lung cancer may be missed since it often occurs only several months later. In a previous trial including patients of any age, a scoring system was tested to facilitate the correct diagnosis of radiation pneumonitis. Since elderly lung cancer patients have a greater risk of developing this complication, a separate scoring system for this group appears useful. Our prospective multi-center trial (NCT06480734) investigates a specific tool for elderly patients irradiated for lung cancer. <b>Methods:</b> Patients aged ≥65 years with lung cancer will complete paper-based questionnaires and rate symptoms potentially caused by pneumonitis weekly during and up to 24 weeks following radiotherapy. The total score of this symptom-based scoring system ranging from 0 to 9 points is correlated to pneumonitis. The discriminative power of the scoring system is evaluated by calculating the area under the receiver operating characteristic curve. Optimality is defined as a cut-off score with sensitivity ≥90% and specificity ≥80%. Moreover, the Youden index will be applied. Fifty-nine patients are required for the full analysis set. Assuming 5% will not qualify for this set, 65 patients should be enrolled. Moreover, patient satisfaction with the scoring system is evaluated. If the dissatisfaction rate is >20%, the system needs modifications; if the dissatisfaction rate is >40%, it is considered not useful. An optimal cut-off score facilitating the diagnosis of pneumonitis and its discrimination from other lung diseases will contribute to a corresponding mobile application to be used by elderly lung cancer patients at home.