A small number of patients (5-7% of all cancer cases) have a genetic predisposition to develop tumors. This means that these people have a mutation in their genes that significantly increases the likelihood of developing a tumor, which is usually inherited.
Such cases of malignant neoplasms take the form of hereditary (or familial) cancer and develop in middle age. Hereditary forms of cancer are well studied in breast, ovarian, and colorectal cancers.
As a rule, it is possible to suspect a genetic predisposition to a malignant neoplasm if a patient has 2 or more blood relatives who have had cancer. For more precise diagnostics special genetic researches are necessary.
