Late relapses after treatment for acute lymphoblastic leukemia in childhood: a population-based study from the Nordic countries

Seven late relapses of acute lymphoblastic leukemia occurring 5.5 to 12.3 years after cessation of therapy are reported in 986 patients who had discontinued treatment for leukemia acquired before the age of 15. The study covers patients from the five Nordic countries. Of the 434 patients with ALL who had passed 5 years of follow-up without recurrence, seven have subsequently relapsed so far; an estimated cumulative proportion of 6.9% within the 10 years. In addition, we report a girl 15.9 years old at diagnosis who relapsed 7.3 years after cessation of therapy. These findings confirm that "cure" of acute lymphoblastic leukemia treated in the 1970s cannot be considered definite, even 5 years after discontinuation of therapy.