RO + pediatric LCH, carries a bad prognosis in patients failing the 1st line treatment [3]. Patients were divided into two groups according to the period and the treatment they received. Those through LCH III protocol, who received treatment before mid-2012 and having ID MTX during induction but without salvage by 2-Cda. Otherwise, those through LCH IV protocol who received treatment after 2012 without ID MTX in induction but with 2-CdABR salvage treatment; a regimen that has been proved to be effective, but toxic [22]. Nowadays as RO + LCH frequently harbor the BRAFV600E mutation [24], the innovative anti B RAF targeted therapy is becoming in common use in refractory RO + [13, 25]. However, being an off-label, expensive drug with a higher reactivation risk at discontinuation, anti B Raf is becoming a useful option as a 3ed line treatment [25].
ID MTX in LCH III protocol did not prove any effectiveness on survival on the long term, reason for which it has been omitted afterwards in the subsequent LCH IV protocol [4]. In our study, there was a rise in the cumulative incidence of DP in patients not receiving ID MTX with a tendency to be statistically significant. The present updated analysis with 67 patients is more prominent than our previous one which comprised a smaller number of 50 patients [21]. Since pediatric LCH is a rare disease, it is difficult to statistically empower such a comparison at a reasonable alpha error rate. On the other hand, ID MTX was associated with better EFS with statistically significant results, confirming our previous study and others [21, 26].
Failing induction DP RO + comprise most early deaths [6, 22, 27]. Otherwise, disease REA, although rare in RO + , is still responsible of mortality in a small number of patients [28]. In our study, DP was accompanied by the worst OS in relation to REA p