The Significance of Scoliosis in Postirradiated Wilms's Tumor and Neuroblastoma

Abstract

There is a tendency to implicate irradiation as an etiologic feature in all complications subsequent to a course of therapy. Although this is justifiable in many instances, it is important to recognize those late complications which are due to tumor invasion and repair of an infiltrated tissue rather than the direct result of irradiation. In the first instance, it may be impossible to achieve a selective effect of irradiation, since the neoplasm has already in part destroyed the normal structure. In the second instance, the tolerance of the normal tissue included in the therapy beam may inadvertently have been exceeded and late radiation injury may result. The importance of distinguishing the cause of the late change lies in the fact that only thus are protective measures and considerations possible. An excellent illustration of this problem is the development of scoliosis in the long-term survivor who has received radiotherapy for certain childhood axial tumors, such as Wilms's tumor and neuroblastoma. The question has been raised whether the degree of scoliosis is too debilitating to warrant the routine use of irradiation in conjunction with surgery. To answer this, one must have an understanding of the production of the scoliosis, the disturbance in form and function, and the possible deterioration of the curvature during the mid-growth and adolescent growth spurts, as described in longitudinal studies in infantile idiopathic scoliosis (Fig. 1) (4). In addition, the degree of deformity must be weighed against the risk of recurrence of the tumor with loss of life if irradiation is denied. Case Material The three common childhood neoplasms in which the vertebral column is exposed to irradiation are: Wilms's tumor, neuroblastoma, and medulloblastoma. A. Wilms's Tumor: Owings and Radakovich (12) recently reported the experience at Strong Memorial Hospital (Rochester, N. Y.) in 18 cases, with a survival of 55 per cent based on doubling time-not the more usual five-year survival figure. Seven of the survivors in this group have been closely followed with special studies. All of these patients were eighteen months of age or younger at the time of the initial treatment (Tables I A, IB, 1C). Ortho-voltage irradiation (200-280 kv) was employed with an h.v.l. of 1.0 mm. Cu. In the cases treated before 1950, lateral fields, in addition to opposed anterior and posterior fields, were common practice. Since that time, opposed fields overlapping the midline have been the general rule, based on the suggestion by Neuhauser et al. (10). The total tumor dose and dose to the vertebrae are similar, ranging from 3,000 to 4,000 r in three to four weeks. The interval of follow-up studies after treatment ranged from four to twenty-three years. B. Neuroblastoma: As of 1960, 30 cases of neuroblastoma have been treated with 8 survivors for a 26 per cent figure, based on doubling time.