Children with non-Hodgkin lymphoma (NHL) and their parents may have questions about prognosis and survival. A prognosis is the doctor’s best estimate of how cancer will affect someone and how it will respond to treatment. Prognosis and survival depend on many factors. Only a doctor familiar with a child’s medical history, type of cancer, stage and risk group, characteristics of the cancer, treatments chosen and response to treatment can put all of this information together with survival statisticsto arrive at a prognosis.
A prognostic factor is an aspect of the cancer or a characteristic of the child that the doctor will consider when estimating likelihood of relapse and long-term survival. A predictive factor influences how a cancer will respond to a certain treatment. Prognostic and predictive factors are often discussed together, and they both play a part in deciding on a treatment plan and a prognosis.
The following are prognostic and predictive factors for childhood NHL.
Children with NHL that responds well to the first treatments given (called first-line therapy) have a better prognosis than those who respond poorly.
Children with early stage (stage I or II) NHL have a slightly more favourable prognosis. Children with advanced (stage III or IV) NHL have a slightly poorer prognosis.
Lactate dehydrogenase (LDH) levels can give the doctors an idea of how much cancer is in the body, which is called the tumour burden. A higher LDH level is usually linked with a greater tumour burden. LDH is often higher than normal in children with a fast-growing lymphoma.
Lymphoma that is only in the lymph nodes or lymphatic tissue where it started (called the primary site) is more easily treated and has a more favourable prognosis. Lymphoma has a less favourable prognosis when it has spread outside the primary site to organs, such as the lung, liver or spleen.
Some children with NHL in the mediastinummediastinumThe space in the chest between the lungs, breastbone and spine that contains the heart, great blood vessels, thymus, trachea (windpipe), esophagus and lymph nodes., or chest, may have a higher risk of early treatment-related side effects and may need more intensive treatment.
Children with NHL in the brain and spinal cord (called the central nervous system, or CNS) or in the bone marrow have a higher risk that the cancer will come back, or recur, and so need more intensive treatment.
Certain chromosome changes in the cancer cells can affect the prognosis for children with mature B-cell NHL. Children with Burkitt lymphoma who have a gain of 7q or deletion of 13q may have a poorer outcome on certain chemotherapy protocols.
Chromosome changes can also affect the prognosis for children with T-cell lymphoblastic lymphoma. Loss of heterozygosity (LOH) is when one allele, or form, of a gene in the cancer cells stops working. This can mean that a gene that normally helps limit the growth of cancer cells (called a tumour-suppressor gene) stops working. Children with LOH at chromosome 6q may have a poorer prognosis.
The presence of anaplastic lymphoma kinase (ALK) in lymphoma cells is a prognostic factor for children with anaplastic large cell lymphoma (ALCL). Children with lymphoma cells that have ALK, or are ALK-positive, have a better prognosis and higher survival rates. Children with lymphoma cells that don’t have ALK, or are ALK-negative, tend to be diagnosed at a later stage and have a poorer prognosis.
NHL in infants is rare, but infants diagnosed with NHL have a poorer prognosis than older children with NHL. Teenagers diagnosed with diffuse large B-cell lymphoma or T-cell lymphoblastic lymphoma tend to have a poorer prognosis than younger children with these types of NHL.