context: Acute lymphoblastic leukemia ( ALL) is the most common type of cancer in children. It affects certain cells in the immune system, called B cells and T cells. ALL usually affects B cells in children. It's natural to feel worried when you learn your child has acute lymphoblastic leukemia, but keep in mind that almost all children can be cured of this disease. B-cell ALL makes your child more likely to get infections, because he doesn't have the protection of those B cells. The disease starts in your child's bone marrow, which is the spongy center of bones where new blood cells grow. The leukemia cells grow very fast and crowd the bone marrow, so the bone marrow has trouble making enough normal cells. Your child will get chemotherapy to treat the disease. Some kids may need a stem cell transplant, too. During treatment, it's important to keep sick people away, so your child doesn't catch what they have. Once your child is done with treatment, he may be free of ALL. He'll need to keep up with doctor appointments to make sure it doesn't come back. Most of the time, doctors don't know what causes B-cell ALL in children. Some things make this disease more likely, including exposure to high doses of X-rays and other forms of radiation, or cancer treatment with chemotherapy. Children with certain genetic diseases, such as Down syndrome, are also more likely to get ALL. ALL symptoms start when leukemia cells crowd out normal blood cells in bone marrow. The types of symptoms your child has will depend on the numbers of cancer cells and healthy blood cells. Children with B-cell ALL may: Bleed or bruise more easily than usual Feel very tired Get infections more often Lose their appetite Other symptoms include: Bone or joint pain Limping Fever Pale skin Red or purple spots called petechiae on the skin Swollen lymph nodes in the neck, underarms, or groin If the cancer cells travel to your child's liver and spleen, these organs can grow large enough to make the belly swell. In some boys, the testicles can also grow larger. To find out whether your child has B-cell ALL, the doctor may ask you questions like: When did you notice a change in your child? What symptoms does your child have? Does anyone in your family have ALL? Does your child have Down syndrome or any other genetic disease? The doctor may do blood tests to find out whether your child has ALL, and if so, what type it is. They use blood tests to check the number of blood cells and look for sick white blood cells. Your child might also need a bone marrow test. The doctor will take samples of the bone marrow, usually from his leg or spine. For this test, your child will lie down on a table and get a shot that will numb the area. Then the doctor uses a very thin needle to take a small amount of liquid bone marrow and check it under a microscope, looking at the size and shape of the white blood cells. Those that look like they haven't developed fully could be signs that your child has B-cell ALL. When your child is diagnosed with any kind of cancer, you're bound to have a lot of questions for your doctor, such as: What treatments will work best for my child's ALL? How long will it last? What are the chances that it will cure my child? What side effects might it cause? How long will these side effects last? What should I tell my child about the cancer and its treatment? Because this type of ALL grows quickly, your child needs to start treatment as soon as possible. It's best to do that at a center that specializes in childhood cancers. Your child will get treated in phases: Phase one: Your child will go to the hospital and get chemotherapy drugs to kill all the leukemia cells that doctors can find. The goal is to put the cancer in remission. This isn't a cure, but it will let your child's bone marrow start to make healthy blood cells again. Most kids go into remission after 1 month of treatment. Your doctor may call this phase "induction." Phase two: Your child will get chemotherapy drugs to kill any cancer cells that are left in his body. Your doctor may call this phase consolidation or intensification. It lasts 4 to 6 months. Next, your child will get therapy to get rid of all the cancer in his body and keep it from coming back. This is called maintenance. He will get lower doses of chemotherapy for 2 to 3 years. Your doctor will closely check on how the treatment is going. He will test your child's bone marrow soon after treatment starts to make sure it's beating the leukemia. At the end of treatment, the doctor may do blood tests to make sure all the cancer is gone. If the doctor finds cancer cells, your child may need more treatment. Stem cell transplant. If your child doesn't get better with treatment, or the ALL comes back, he may need a stem cell transplant to get the bone marrow working right again. These are not the "embryonic" stem cells you may hear about in the news. These are cells that live in bone marrow and help make new blood cells. When your child gets a stem cell transplant, he'll get cells from a donor. That person might be a close relative, such as a brother or sister, or a matched donor who isn't in your family. The cells might also come from a donated umbilical cord. To prepare for the transplant, doctors will probably give your child high doses of radiation or chemotherapy to kill the cancer cells. After that, he'll get the new stem cells through an IV. It won't hurt. After the transplant, it will take at least a few days for the stem cells to multiply and start making new blood cells. During this time, he may need to stay in the hospital until his white blood cell count rises enough to protect him from infection. Once your child is back at home, he will need to visit a clinic every day for a few weeks to get checked. It can take about 6 months until the number of normal blood cells in his body gets back to what it should be. CAR T-cell Therapy. The FDA has approved a type of gene therapy for both children and adults whose B-cell ALL doesn't get better with other treatments. CAR T-cell therapy uses some of your own immune cells, known as T cells, to treat your cancer. Doctors take the cells out of your blood and change them by adding new genes. The new T cells can work better to find and kill cancer cells. Treatments for B-cell ALL can make infections more likely. Try to keep him away from anyone who is sick. Everyone who is close to your child should get vaccinated for diseases like the flu and pneumonia, and should wash their hands often. A cancer diagnosis can be very hard for a child. He may have questions or fears you don't know about. Make sure your child gets the emotional support he needs during this time. Friends, family members, social workers, and therapists can all be a big help. Your child also may need extra tutoring to make up for lost time at school. Treatments for B-cell ALL have improved a lot over the last 30 years. Today, most children treated for this cancer are cancer-free. After being cured, your child will still need to see the doctor often, to make sure the cancer doesn't come back. The doctor will also check for problems ALL treatments can cause, including damage to the heart and other types of cancers. Over time, your child will visit the doctor less often. To learn more about B-cell acute lymphoblastic leukemia in children, or to find a support group in your area, visit the websites of the Childhood Leukemia Foundation and the Leukemia & Lymphoma Society.