Reduction of adult height in childhood acute lymphoblastic leukemia survivors after prophylactic cranial irradiation.

Background: Impaired linear growth is a well-recognized complication in long-term childhood ALL survivors who received cranial irradiation. However, as many patients achieve a final height between the 5th and the 95th centile, the true incidence of linear growth impairment might be underestimated.

Methods: Reduction of adult height (RAH) was estimated in adult childhood ALL survivors with and without cranial irradiation. RAH was calculated as the difference between target height (TH) and final height (FH). TH was calculated according to the formula TH = {[(height father + height mother +/- 12)/2] + 3}. RAH was assessed in 79 adult childhood ALL survivors in first complete remission who had received cranial irradiation 25 Gy (Group I, n = 53), 18 Gy (Group II, n = 10) or chemotherapy alone (controls, n = 16).

Results: RAH was 8.6 +/- 8.2 cm in Group I (P = 0.001 vs. controls), 6.2 +/- 3.2 cm in Group II (P = 0.01 vs. controls), and 1.7 +/- 4.6 in controls (chemotherapy only). There was no significant difference between Group I and Group II. In Group I females had more RAH than males (P = 0.02). RAH was related to younger age at diagnosis (P = 0.001).

Conclusions: The deficit between target height and final height highlights the reduction of adult height in the majority of male and female childhood ALL survivors who had received prophylactic cranial irradiation, in particular in those who were diagnosed at a younger age. This reduction would have been masked if patients FH was only compared with standard methods. RAH might be a sensitive predictor for growth hormone deficiency as these results suggest that radiation-induced growth hormone deficiency in these patients is the rule rather than the exception.