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Interobserver Reliability in Describing Radiographic Lung Changes After Stereotactic Body Radiation Therapy

2017; Elsevier BV; Volume: 99; Issue: 2 Linguagem: Inglês

10.1016/j.ijrobp.2017.06.487

1879-355X

Noah S. Kalman, G Hugo, Jonathan B. Kahn, Sherry Zhao, Nuzhat Jan, R.N. Mahon, Elisabeth Weiss,

Head and Neck Cancer Studies

Radiographic lung changes after stereotactic body radiotherapy (SBRT) vary widely between patients. Accurate interpretation of post-SBRT radiographic change is critical to identify tumor recurrence versus benign change. Standardized descriptions of acute (within 6 months of treatment) and late (>6 months after treatment) lung changes have been proposed (Bradley et al., Lung Cancer 2011). These descriptions help identify benign radiographic change, but the reliable application of these classification systems has not been demonstrated. Herein we examine the inter-observer reliability of classifying acute and early late lung changes after SBRT. Two hundred eighty follow-up CT scans at 3, 6, and 12 months post-treatment were analyzed in 100 patients undergoing thoracic SBRT. All patients had 3 and 6 month scans performed. Standardized descriptions of acute lung changes (3 and 6 month scans) include diffuse consolidation (group 1), patchy consolidation and ground glass opacity (GGO) (group 2), diffuse GGO (group 3), patchy GGO (group 4), and no change (group 5). Late lung change classifications (12 month scans) include modified conventional pattern (group A), mass-like pattern (group B), scar-like pattern (group C), and no change (group D). Four physicians scored the images independently in a blinded fashion. Fleiss’ kappa scores were used to quantify inter-observer agreement. Kappa scores were 0.30 at 3 months, 0.20 at 6 months, and 0.25 at 12 months. The proportion of patients in each category at 3 months was as follows: 1, 11%; 2, 15%; 3, 10%; 4, 15%; and 5, 49%. At 6 months, classifications were as follows: 1, 21%; 2, 28%; 3, 11%; 4, 15%; and 5, 25%. The percentage of patients in each category at 12 months was as follows: A, 46%; B, 16%; C, 26%; D, 12%. Uniform scoring occurred in 26, 8, and 14 cases at 3, 6, and 12 months, respectively. In 85% of consensus descriptions of acute lung changes, no change (group 5) was observed. At 12 months, 79% of consensus descriptions observed modified conventional pattern (group A). Inter-observer reliability scores indicate a poor to moderate agreement for acute and early late lung change classifications after SBRT. Qualitative descriptions of post-SBRT radiographic lung changes are insufficient to categorize these findings, as most patient scans do not fit clearly into a single classification. Objective measures of radiographic lung changes may offer a better alternative to categorize these changes than qualitative descriptions.