In September we recognize quite a few types of cancers, including uterine, prostate, ovarian, and thyroid cancers. While all these types of cancers are important, September is also blood cancer awareness month: a focused time for advocates and supporters of leukemia to raise awareness about efforts to fight blood cancers like leukemia. Leukemia cancer affects both children and adults but is the most common cancer in children and teens.
Causes of Leukemia Cancers
Our bone marrow inside our bones produce blood cells, which are important for carrying oxygen and iron throughout our bodies, among other important tasks. Leukemia is a cancer that starts in the bone marrow or newly formed blood cells. Typically, leukemia is a cancer of the white blood cells, but leukemia can also start in other types of blood cells. There are several types of leukemia, but the majority are divided into two categories: acute, which means fast growing cancer, or chronic, which is slow growing. The two main types of acute leukemia are Acute Lymphocytic Leukemia (ALL) and Acute Myeloid Leukemia (AML). ALL is a cancer that develops in the lymphocytes, a type of white blood cell or a cell that helps with your immune system. AML is a cancer that develops in the bone marrow in cells called myeloid cells, which are precursor cells to mature blood cells and platelets. There are three main types of chronic leukemia: chronic lymphocytic leukemia, chronic myeloid leukemia, and chronic myelomonocytic leukemia (myelomonocytic cells are another precursor cell to the different types of white blood cells).
ALL can be caused by both environmental factors as well as genetic components. For example, radiation exposure, certain chemical exposures, and viral infections can increase a person’s risk to develop ALL. There doesn’t appear to be a strong inherited genetic component for ALL by itself. However, a person’s risk can be increased to develop ALL if they have certain genetic syndromes. Down syndrome and Klinefelter syndrome are both chromosome abnormalities that result in an extra chromosome. Both of these syndromes have an increased risk to develop ALL. In addition, Fanconi anemia, Bloom syndrome, Ataxia-Telangiectasia, neurofibromatosis, and Li-Fraumeni syndrome all are associated with an increased risk to develop ALL.
AML is similar to ALL in that there are many similar syndromes that cause an increased risk for a person to develop AML. However, there is also a familial form of AML caused by a mutation in the CEBPA gene. While AML is typically a cancer that occurs in older adults, if a family is diagnosed with a mutation in the CEBPA gene there is an increased risk to develop AML earlier in life, reportedly as early as age 4. Between 50-65% of individuals with familial AML survive their cancer, compared to only 25-40% of other forms of AML. However, individuals with familial AML have a higher risk of developing a second AML at some point in their life. The mutated CEBPA gene is passed in families in an autosomal dominant pattern, which means that each family member is at a 50% risk of inheriting the mutated gene.
Genetic Indicators for Leukemia
While there can be inherited syndromes or gene mutations that cause an increased risk for Leukemia, there are also sporadic changes to our genes or chromosomes that come from an environmental cause. For example, in most cases of chronic lymphocytic leukemia (CLL), a change can be found in at least one of the chromosomes inside the cancer cells. These changes weren’t inherited, but rather occurred through exposure to the environment. The most often change in chromosomes in CLL is a deletion of a portion of a chromosome. The loss of part of chromosome 13 is the most common deletion, but chromosomes 11 and 17 can be affected as well. Knowing these types of genetic changes in the different types of Leukemia can determine more accurate treatment methods and a better idea of how a person will respond to different treatment options.
How Genetics & Genetic Testing Can Help
There is a lot of progress in the research and study of genetics of many types of cancers. Today, when a person is diagnosed with leukemia, a genetic test is performed to determine what type of treatment is best to use and what the prognosis will be. As research continues to progress, hopefully these types of cancers will be able to be cured even faster or completely eliminated.
If you are interested in learning more about leukemia or the genetics of leukemia, or if you have a family history of leukemia and are interested in pursuing genetic testing, please contact AT-GC to meet with a genetic counselor.