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Thoracic reirradiation for lung cancer: a literature review and practical guide.

INTRODUCTION
Approximately half of all patients with lung cancer (LC) experience locoregional failure after initial treatment. Historically, thoracic reirradiation (ReRT) has been limited by toxicity concerns and lack of robust evidence. Our objective was to perform a systematic literature review regarding ReRT.


METHODS
Search of the English-language literature related to best-practice thoracic ReRT (Medline and Embase) was performed. Clinical practice guidelines and consensus statements were also reviewed. Data was abstracted regarding patient, tumour and radiotherapy characteristics; response rate; overall survival (OS); and toxicity. In addition to descriptive analysis, Spearman's test explored relationships between RT dose and OS.


RESULTS
A total of 379 patients (89% non-small cell; 11% small cell LC) retreated with radical or palliative intent have been described by 13 publications (1982-2014). A total of 86% were symptomatic at the time of ReRT; rate of symptom improvement was 69%. Range of reported median survivals (MS) was 3-15 months. Median initial (59 Gy; range, 12-80 Gy), ReRT (36 Gy; range, 12-70 Gy) and combined dose (86 Gy; range, 58-120 Gy) significantly correlated with OS, with Spearman's rho values of 0.85 (P=0.002), 0.72 (P=0.006), and 0.88 (P=0.001) respectively. Toxicity after ReRT was reported in 17% (esophagitis) and 12% (pneumonitis), with RT complications contributing to 2% of deaths.


CONCLUSIONS
Despite heterogeneity of patient cohorts, RT techniques and duration of follow-up, ReRT appears to be a feasible option for recurrent thoracic disease. Treatment guidelines derived from this data will guide clinical decision-making for both radical- and palliative-intent ReRT.