Table 1 Cardinal features of hereditary cancer

* Earlier average age of cancer onset than in the general population; for example, the average age of CRC onset in HNPCC is ≈45 years, while the average age of onset in sporadic CRC is ≈63 years [6].

* A pattern of primary cancers segregating within the pedigree [6, 19].

* Possible survival differences [71, 79–81].

* Occasional pathology distinguishing features [82, 83].

* The sine qua non, the identification of a germline mutation segregating with syndrome-affected individuals in the family [45].