Childhood+Acute+Lymphoblastic+Leukemia

Grace is a 6 year-old, white female whose parents checked her into O’Connor Hospital today because she was experiencing severe joint pain, fever, and bruising throughout her body. Over the past month Grace has been lethargic, despite sleeping more frequently, and her appetite has substantially decreased. Grace’s parents initially suspected the common cold or flu given she began school this year and as a result, has had direct exposure to many viruses going around. However, as their daughter continually complained about her body aching and they discovered a lump in her underarm, they suspected Grace’s condition to be something more severe.

In the initial patient consult, the physician saw this was not just any illness and transferred Grace to a pediatric oncologist for further examination of her condition. There, the pediatric oncologist evaluates Grace’s physical state and finds petechiae, or red spots, on the skin as well as excessive bruising and the swollen glands in her underarms.1,5 From these symptoms alone she determines that Grace has likely fallen victim to childhood leukemia. The oncologist explains her suspicions to Grace’s parents and that this leukemia could either be acute lymphoblastic or acute myeloid. To elucidate the difference between the two as well as the disease itself the oncologist gives a brief biological overview.

In a normal, healthy individual, the bone marrow makes blood stem cells that become mature cells over time. These cells become myeloid stem cells or lymphoid stem cells and develop as illustrated in Figure 1. Both B and T lymphocytes make antibodies to fight infection, whereas the killer cells specifically target cancer cells and viruses.

Leukemia is the most prevalent form of cancer in children, accounting for 1 of 3 cancer cases in child patients. There are two main forms of leukemia in children: acute lymphoblastic leukemia and acute myeloid leukemia. The oncologist might suspect acute lymphoblastic leukemia, as it accounts for 75% of all childhood leukemia cases. Within acute lymphoblastic leukemia, there are four subcategories: Early Pre-B cell, Pre-B Cell, Mature B cell, and T cell.

In a child with acute lymphoblastic leukemia, too many blood stem cells become lymphoids and give rise to immature lymphoblasts. These stem cells replicate, unregulated, creating a large amount of immature lymphoblasts in the bone marrow, which crowd out the normal, healthy cells. This leads to infection, anemia, and easy bleeding, as the white blood cells, red blood cells, and platelets can no longer function at their normal capacity.1,3 To confirm this is Grace’s illness, blood chemistry studies will have to be done on blood samples taken from the patient. Along with this test a complete blood count will be done on the blood sample to gauge the seriousness of Grace’s leukemia.

Other tests the oncologist would likely perform to understand Grace’s leukemia and its’ severity include a Lumbar puncture, a chest x-ray, and a bone marrow aspiration and biopsy. The lumbar puncture will check to see if the cancer cells have spread to Grace’s cerebrospinal fluid. This test involves sticking a needle into the patient’s spinal column and withdrawing the fluid. The chest x-ray will help the doctor determine if the cells have formed a mass in the chest of the patient. Lastly, a bone marrow aspiration and biopsy will allow the oncologist to do a cytogenetic analysis on the bone marrow or blood and see if there are any changes in chromosomes or genes. This is done by inserting a hollow needle into the hip bone or breast bone of the patient and removing a sample of the bone marrow.1

If the oncologist’s assumption is correct and Grace has acute lymphoblastic leukemia she can further categorize her illness. Within the scope of acute lymphoblastic leukemia, a patient is usually labeled as low-risk or high-risk. These classifications are based off multiple criteria, including age, white blood cell count at the time of the diagnosis, immediate response to treatment, whether leukemia cells are found in the cerebrospinal fluid, and whether any genes or chromosomes have been mutated.2 A child within the age range of 1-9 is usually considered low risk, ignoring other factors, while a child under 1 or older than 10 is usually categorized as high risk. This is because children generally within the age range of 1-9 tend to have certain cytogenetic traits, like hyperdiploidy- more than the normal diploid number of chromosomes- making treatment more beneficial. Also a white blood cell count greater than 50,000 cells per microliter is considered high risk, as this is higher than an average 10,000 cells per microliter inferring there is a large accumulation of these lymphoblasts, crowding out the all of the healthy blood cells. Further, the sub-type of the leukemia also plays a role, as children with Early Pre-B cell or Pre-B cell acute lymphoblastic leukemia have a better outlook as the leukemia cells are not as mature and developed. Lastly, if the leukemia cells have spread to the cerebrospinal fluid, the child is automatically placed in the high-risk category, as this means the cancer has metastasized to the central nervous system.6,7

The prognosis for a child with acute lymphoblastic leukemia is a lot more positive than for an adult. If Grace does have acute lymphoblastic leukemia it can likely be cured, as the current 5-year survival rate is 85 percent. The odds of course vary depending on when treatment was given in the cancer’s development, characteristics of the patient, whether they were high or low risk, and their individual response to treatment. Despite the treatment of acute lymphoblastic leukemia being very successful, the damage resulting from radiation treatment and chemotherapy largely increases the child’s risk for developing other types of cancer within their lifetime. If Grace enters the maintenance stage in treatment of the leukemia, it is important she be monitored closely for new cancer symptoms or a possible relapse.1,4