SIOP treatment guidelines for renal tumours in small infants: fact or fantasy?

Aims: Since as far back as 1980, SIOP (Société Internationale d>>Oncologie Pédiatrique) have advocated primary nephrectomy (PN) only for unilateral renal tumours in patients </=6 months of age. Patients aged 7-12 months have been pre-treated with chemotherapy before nephrectomy is performed. The aims of this study were: (1) to evaluate how the SIOP guidelines for infants 0-6 months and 7-12 months of age were followed in three Dutch centres for Paediatric Oncology before and after 1980, and (2) to carry out an inventory of the incidence of benign tumours in this patient population below 12 months of age.

Methods: Retrospective analysis of 67 patients under 12 months of age (1969-1995) with a unilateral renal tumour at diagnosis was carried out. Demographics, pathology, staging and treatment variables were analysed.

Results: Of 67 patients, 39 were male and 28 female. Twenty-six (39%) infants were 0-6 months of age (group A) and 41 (61%) were 7-12 months old (group B). In group A there were five patients (19%) with congenital mesoblastic nephroma (CMN), out of which one was still-born and therefore received no treatment, and 21 patients with a unilateral Wilms>> tumour (WT). Fourteen of the 25 patients (56%) were treated with PN, including four patients with CMN. In group B there was one patient (2%) with CMN and 40 patients with WT. Thirteen of the patients (31%) were treated with PN. A total of 15 patients were treated before 1980 and 26 after 1980. Eight of 15 (53%) patients were treated with PN before 1980 and 21/26 (81%) were pre-treated after 1980, according to the protocol.

Conclusion: Despite the SIOP recommendations, only 56% of patients </=6 months were treated with PN. The percentage of pre-treated patients in group B increased after changing the protocol in 1980 to 81%. In the age group included in the SIOP studies the protocol had been used significantly more often compared to the group included in the guidelines only. The known excellent survival rate justifies a primary nephrectomy approach in the youngest age group, however, in cases of a large tumour, pre-operative chemotherapy in reduced doses may still be considered. In our study fewer CMN were found (19%) than reported in the SIOP studies (20-70%), most likely due to a low registration rate, as a consequence of excluding this very young age group (0-6 months) from the SIOP protocol.