Improving outcomes in non-small cell lung cancer; optimum dose fractionation in radical radiotherapy matters
Menée en Angleterre à l'aide de données 2012-2016 portant sur 73 186 patients atteints d'un cancer du poumon non à petites cellules de stade I-III, cette étude compare l'intérêt, du point de vue de la survie, de deux protocoles de radiothérapie, l'un par hypofractionnement modéré (55 Gy en 20 fractions) et l'autre par fractionnement conventionnel (60-66 Gy en 30-33 fractions)
Introduction: We analysed a comprehensive national radiotherapy dataset to compare outcome of the most frequently used moderate hypofractionation regimen (55Gy in 20 fractions) and conventional fractionation (60-66Gy in 30-33 fractions). Patients & Methods: 169,863 cases of non-small cell lung cancer (NSCLC) registered in England from January 2012 to December 2016 obtained from Public Health England were divided into Cohort 1 (training set) diagnosed 2012-13 and Cohort 2 (validation set) diagnosed 2014-16. Radiotherapy data was obtained from the National Radiotherapy Dataset and linked by NHS number to survival data from Office of National Statistics and Hospital Episode Statistics from which surgical data and Charlson comorbidity Index were obtained. Of 73186 patients with stage I-III NSCLC 12898 received radical fractionated radiotherapy (cohort 1 – 4894; cohort 2 – 8004). Multivariate proportional hazards model was used to investigate overall survival from time of diagnosis. Survival was adjusted for the prognostic factors of age, gender, stage of disease, comorbidity, other radical treatments and adjuvant chemotherapy and the difference between the treatment schedules was summarised by the hazard ratio (HR) and 95% confidence interval (95% CI). The significance of any difference was assessed by the log likelihood test. Results: 17-18% of patients with stage I-III NSCLC received fractionated radical radiotherapy. After adjustment for independent prognostic factors of age, stage, comorbidity and other radical and adjuvant treatments, patients in Cohort 1 treated with the 2.75 Gy per fraction regimen had a median survival of 25 months compared to 29 months for patients treated with the 2 Gy per fraction regimen (HR = 1.16; p=0.001). Similarly in Cohort 2 the respective median survival values were 25 and 28 months (HR=1.10; p=0.02). Conclusion: Big data analysis of a comprehensive national cohort of NSCLC patients treated in England suggests that compared to a 4-week regimen of 55Gy in 20 fractions, a 6-week regimen of conventional daily fractionation to a dose of 60-66 Gy at 2 Gy per fraction is associated with a survival benefit. Within the limitations of retrospective big data analysis with potential selection bias and in the absence of randomised trials, the results suggest that conventional fractionation regimens should remain the standard of care.