Table 2.

Overview about grading scales for radiation-induced lung fibrosis

Grading scale	Grade 1	Grade 2	Grade 3	Grade 4	Grade 5
CTCAE v5.0	Radiologic pulmonary fibrosis < 25% of lung volume associated with hypoxia	Evidence of pulmonary hypertension; radiographic pulmonary fibrosis 25–50% associated with hypoxia	Severe hypoxia; evidence of right-sided heart failure; radiographic pulmonary fibrosis > 50–75%	Life-threatening consequences (e.g., hemodynamic/pulmonary complications); intubation with ventilatory support indicated; radiographic pulmonary fibrosis > 75% with severe honeycombing	Death
RTOG	Asymptomatic or mild symptoms (dry cough); slight radiographic appearances	Moderate symptomatic fibrosis (severe cough); low grade fever; patchy radiographic appearances	Severe symptomatic fibrosis; dense radiographic changes	Severe respiratory insufficiency/ Continuous O2/ Assisted ventilation	Death
LENT-SOMA (EORTC)	Asymptomatic or mild symptoms; radiological abnormalities; 10–25% reduction of respiration volume and/or diffusion capacity	Moderate symptoms; patchy dense abnormalities in imaging; > 25–50% reduction of respiration volume and/or diffusion capacity	Severe symptoms; dense confluent radiographic changes limited to irradation field; > 50–75% reduction of respiration volume and/or diffusion capacity	Severe symptoms requiring continuous O2 or assisted ventilation; dense fibrosis, severe scarring & major retraction of normal lung; > 75% reduction of respiration volume and/or diffusion capacity	Death

CTCAE v5.0 Common terminology criteria for adverse events, version 5.0, RTOG Radiation Therapy Oncology Group, EORTC European Organization for Research and Treatment of Cancer, LENT-SOMA Late effects in normal tissue-subjective objective management analysis