Definition of the four levels of nested criteria according to the number and tumour type in the affected relative(s) in the study on childhood cancer
| Criteria on relatives | Definition |
| Very loose | At least one first or second degree relative affected by any cancer |
| Loose | Tumour type in the affected relative(s) restricted to sarcoma, brain tumours, breast cancer, adrenocortical carcinoma, haematological malignancies, stomach cancer, melanoma, and germ cell tumours |
| Stringent | Tumour spectrum in relative(s) restricted to unquestioned tumours, ie sarcomas, brain tumours, breast cancer, and adrenocortical carcinoma (narrow spectrum) |
| Very stringent | New criterion added to the previous ones: at least another first or second degree relative affected by cancer before 46 years or a sarcoma at any age |