Results of the Treatment for Relapsed Acute Lymphoblastic Leukemia (ALL) in Childhood

Relapses occur in 25–30% of childhood ALL. We evaluated the outcome of this group of patients (pts) according to the duration of the 1^st CR, immunophenotype and site of relapse in our Institution.

From Sept’94 to Aug’09, 245 ALL relapses were diagnosed: 73 cases were not evaluable due to: different treatments received (n: 36), palliative care (n: 26) and insufficient data (n: 11); 172 pts were evaluable (54 F/118 M), with a mean age at the moment of the relapse of 9.8 (range 1.8–20.8) years. Induction therapy combined a pre-phase with 10 days of prednisone and 1 block of high doses of chemotherapy, followed by 5 blocks of similar intensity, CNS or testicular (preventive/therapeutic) radiotherapy, and weekly rotational maintenance, until completing two years from the moment of diagnosis. High-risk relapsed pts who had an available identical donor received HSCT.

Immunophenotype was B-cell precursor (Bcp) in 89% of the pts and T-cell in 11 %. The duration of the 1^st CR was <18 mo in 41 (24%), 18–36 mo in 79 (46%), >36 mo in 52 (30%) pts. The sites of relapse were bone marrow (BM) in 106 pts (61%), combined bone marrow (cBM) in 27 pts (17%) and isolated extramedullar in 39 pts (22%). The response to induction was: CR 134 pts (78%), death during induction 20 pts (12%) and partial/null response 18 pts (10%). Among the 134 pts who achieved CR, 69 (52%) presented a second relapse at 18,8 (r 0.7–88.8) mo from the 2^nd CR, 10 (7%) died in CR and 1 developed a 2^nd neoplasm. With a mean follow-up of 49 (r 2–155) mo, 54 pts remain in CR, 37 of them out of therapy. Of the 26 pts who received HSCT, 12 relapsed and 3 died in CR. The EFSp (SE) for the total group of pts was 25 (3)% and LFS probability (SE) 33 (4)%; for Bcp relapses it was 28%, and for T relapses 6% (P=0.0025); for BM+cBM cases it was 21%, and 40% for extramedullar (P=0.0061). However, testicular relapses achieved EFSp of 80%, and 12% for the remaining extramedullar cases (P=0.0004). The EFSp for relapses at <18mo of 1^st CR was 5%, between 18–36 mo 25% and >36 m 41% (P=0.0001).

The immunophenotype, the duration of the 1^st CR and site of relapse significantly influenced the EFSp. Isolated testicular relapses achieved the best EFSp. HSCT is an eligible option for a small group of pts. New therapeutic approaches must be developed to improve outcome of most of relapsed ALL patients.

No relevant conflicts of interest to declare.