Blood cancers are diseases that begin in the bone marrow or blood cells, affecting their normal production and function. These conditions include leukemia, lymphoma, and myeloma, the three most common types. Leukemia originates in the blood and bone marrow, often involving an overproduction of abnormal white blood cells. Lymphoma develops in the lymphatic system, a part of the immune system, while myeloma affects plasma cells in the bone marrow.
Understanding Inherited Predisposition
Most blood cancers do not arise from genes directly passed down from parents. However, some individuals can inherit a genetic predisposition, meaning they have an increased likelihood of developing these cancers. “Inherited” refers to germline mutations present in all cells from birth, passed from a parent. In contrast, “acquired” or somatic mutations occur during a person’s lifetime in specific cells and are not transmitted to offspring.
Inheriting a predisposition does not guarantee that a person will develop cancer; it simply elevates their risk compared to the general population. Cancer development often requires additional genetic changes or environmental triggers. Sometimes, multiple family members may develop cancer without a clear inherited gene, possibly due to shared environmental exposures or common genetic variants that individually confer a lower risk. Approximately 5% to 10% of all cancers are considered hereditary.
Blood Cancers with Genetic Links
Specific types of blood cancers are associated with inherited genetic components or syndromes. Certain conditions significantly increase the risk of leukemia. Children with Down syndrome, characterized by an extra copy of chromosome 21, are 10 to 30 times more likely to develop leukemia. They face a particularly elevated risk for acute myeloid leukemia (AML), being up to 150 times more likely to develop it, and 33 times more likely for acute lymphoblastic leukemia (ALL).
Other inherited syndromes also increase leukemia risk, including Li-Fraumeni syndrome, which involves mutations in the TP53 tumor suppressor gene. Fanconi anemia and Bloom syndrome are also linked to an elevated risk of leukemia. Specific inherited gene mutations, such as those in RUNX1, GATA2, and CEBPA, can directly predispose individuals to certain leukemias, particularly AML.
For lymphoma, a family history can slightly increase risk. Conditions like certain primary immunodeficiency disorders can raise lymphoma risk by weakening the immune system. Genes such as BRCA1 and BRCA2, commonly associated with breast and ovarian cancers, have also been linked to an increased risk of lymphoma. Familial clusters of myeloma suggest a complex genetic predisposition influencing the risk for this plasma cell cancer.
Factors Beyond Inherited Genes
The development of blood cancer is rarely due to inherited genes alone; other elements contribute significantly. Environmental factors play a role, with exposure to certain chemicals, such as benzene and cigarette smoke, increasing leukemia risk. High levels of ionizing radiation, whether from nuclear accidents or medical treatments, can also damage cellular DNA and elevate the risk of certain leukemias.
Lifestyle choices, including smoking, introduce harmful chemicals that can lead to DNA damage. Medical history, such as prior chemotherapy or radiation therapy for other cancers, can sometimes increase the risk of developing secondary blood cancers. Certain viral infections, such as Epstein-Barr Virus (EBV) and Human Immunodeficiency Virus (HIV), are associated with an increased risk of specific lymphomas, particularly in individuals with weakened immune systems.
Genetic Counseling and Screening
Individuals and families concerned about a possible hereditary risk for blood cancer can seek guidance from genetic counselors. These specialists assess family medical history to identify patterns that might suggest an inherited predisposition. Genetic counseling involves discussing the implications of genetic risk and explaining the available testing options.
Genetic testing for cancer predisposition typically involves a blood or saliva sample. A positive test result indicates the presence of a mutation that increases cancer risk, but it does not predict whether cancer will definitely develop. Based on identified risks, genetic counselors can recommend increased surveillance or specific screening protocols to monitor for early signs of cancer.