Pediatric patients who undergo chemotherapy for ALL are at higher risks for fractures and decreased bone mineral density. This is due to the leukemia cells triggering osteoclast mediated bone resorption and this reduces bone growth and density.
Acute Lymphoblastic Leukemia (ALL) is a cancer of the blood and bone marrow. It is the most common type of cancer in children and most often occurs in ages 2-5. The most common treatment for ALL is chemotherapy and due to advancements in treatment, the overall cure rate in children is around 90%. With ALL, the cancer cells grow rapidly in the bone marrow. They are called blasts, which are immature white blood cells. Patients with ALL have too many blasts in their bone marrow. These cells don’t work normally, and they crowd out normal white blood cells, red blood cells, and platelets. The blast cells reduce hematopoiesis (red blood cell synthesis) and cause anemia, thrombocytopenia, and neutropenia. They attack the white blood cells that fight infection and protect the body from disease. This increases the risk of developing infections that can be fatal. (stjude.org)
There are two types of lymphocytes: B-lymphocytes and T-lymphocytes. ALL can be known as B-cell or T-cell ALL. B-cell ALL is the most common fom of ALL. Most cases of ALL have no known cause.
Symptoms of ALL are anemia with weakness and fatigue, low white blood cell count (Leukopenia) with frequent infections, thrombocytopenia with bruising and bleeding, and bone and joint pain. Some children will present with an unwillingness to walk because of this bone pain, which is caused by leukemia penetrating the periosteum, bone, or joint or because of expansion of the marrow cavity by leukemia cells. Children with significant bone pain can often have almost normal blood counts, which can contribute to delayed diagnosis and treatment. (Angsubhakorn et al., 2018)
Other reasons for low bone density in ALL survivors are the disease process, damage to endocrine organs that control bone growth, poor nutrition, genetic predisposition, inactivity, and puberty. After completing therapy, the bone mineral depletion may predispose survivors to osteoporosis with greater severity and earlier onset. Osteoporosis is a disease in which bone resorption exceeds deposit. The cell matrix remains normal, but bone mass declines. The most susceptible are the spongy bone of the spine and the head and neck of the femur. Low peak bone mass is a risk factor for osteoporosis later in life. (Ahn et al., 2020)
Overall, low bone mass density became more common with increasing time after the diagnosis of ALL. (Mostoufi-Moab et al, 2019)
Kaste, S.C., Rai, S.N., Fleming, K., McCammon, E.A., Tylavsky, F.A., Danish, R.K., Rose, S.R., Sitter, C.D., Pui, C.-H. and Hudson, M.M. (2006), Changes in bone mineral density in survivors of childhood acute lymphoblastic leukemia. Pediatr. Blood Cancer, 46: 77-87. https://doi.org/10.1002/pbc.20553
Ahn, M. B., & Suh, B. K. (2020). Bone morbidity in pediatric acute lymphoblastic leukemia. Annals of pediatric endocrinology & metabolism, 25(1), 1–9. https://doi.org/10.6065/apem.2020.25.1.1
Mostoufi-Moab, S., & Ward, L. M. (2019). Skeletal Morbidity in Children and Adolescents during and following Cancer Therapy. Hormone research in paediatrics, 91(2), 137–151. https://doi.org/10.1159/000494809
Angsubhakorn, N., & Suvannasankha, A. (2018). Acute lymphoblastic leukaemia with osteolytic bone lesions: diagnostic dilemma. BMJ case reports, 2018, bcr2018225008. https://doi.org/10.1136/bcr-2018-225008