More than 100 types of childhood cancer
There are more than 100 types of childhood cancer, different from adults. The frequency varies depending on age: early childhood for nephroblastomas, neuroblastomas and rhabdomyosarcomas, later on for bone tumors and lymphomas. The most frequently observed tumors are leukemias which represent 30 % of all malignancies, followed by central nervous system tumors (20 %).
There are 2 big groupings of childhood leukemia: lymphoblastic leukemia which represents approximately 85% of cases, and the much rarer myeloblastic leukemia. Initiated in the 70s, multi-drug therapies currently permit, and thanks to the progress associated treatments (antibiotics, transfusion support, use of central catheters), a cure rate of 80 % in children with acute lymphoblastic leukemia, with variations in prognosis depending on the sub-type. Acute myeloblastic leukemia currently has a cure rate of about 50%.
Lymphomas and Hodgkin’s disease
Like other childhood tumors, childhood lymphomas differ from those of adults by their rapid development, whether they be abdominal tumors from Burkitt’s lymphoma or mediastianal lymphomas. The cure rate of abdominal and thoracic lymphomas is currently anywhere from 75% to 90 %, according to published reports. In the case of Hodgkin’s disease, for at least the past 20 years we have been able to cure between 80 to 90 % of affected children using a treatment combining chemotherapy and radiation, but the long term side effects from treatments from the 70s were extensive. During the last decade, efforts focused on gradually and simultaneously decreasing volumes and doses of radiation and the progressive elimination of the most aggressive medicines causing long term side effects.
The nephroblastoma or the Wilms tumor
This childhood kidney cancer was one of the first ones to benefit from the development of chemotherapy. More than half of nephroblastomas are treated starting with a brief period of chemotherapy, followed by surgery (ablation of the diseased kidney), and a few weeks of chemotherapy. The more extensive tumors must be treated without radiation, but with more intense chemotherapy. Approximately 25% of patients still need radiation and aggressive chemotherapy. At present, 90% of nephroblastomas are cured by these treatments.
Osteosarcomas are tumors located in the long bones (tibia, femur, humerus). At present, treatment starts with chemotherapy using méthotrexate principally, which allows a reduction of the tumor, followed by surgery to remove the diseased part of the bone, usually replaced by a customized metal implant. The functional outcomes of these treatments are excellent. We can now apply them in three quarters of patients affected by osteosarcomas. In the past, metastases represented a great risk for children, but their frequency has gone from 80 to 90% 20 years ago to 25% at present, thanks to the systematic use of chemotherapy before and after surgery.
Rhabdomyosarcomas, Ewing’s sarcoma and neuroblastomas
Rhabdomyosarcomas are unique to small children; they affect above all the ENT and the uro-genital spheres. Results, while very encouraging, are nevertheless still incomplete, with a cure rate estimated at 65%. The same is true for Ewing’s, bone tumors affecting flat bones (ribs, vertebrae, pelvis) and which pose difficult therapeutic problems. Most of the time, treatment is based on a mix of chemotherapy-radiation-surgery. The cure rates are estimated at 65%.
Neuroblastomas are sympathetic nervous system tumors (adrenal glands and sympathetic ganglia) which can be divided into 3 entities: tumors in newborns, quite exceptional, and for which the prognosis is very favorable; localized tumors, the treatment of which is essentially surgical after chemotherapy perhaps for tumor reduction, the cure rates of which are also very high; finally, the metastatic tumors, in particular in the bone marrow and skeleton. They are chemo-sensitive, but difficult to cure with chemotherapy. The metastatic neuroblastoma is at present cured only in approximately 30% of cases.
Brain tumors are the most frequent solid tumors of the child. These cancers are also the ones for which therapeutic progress has been the least important during the past decades. However, today, neuro-surgical techniques, medical imaging using scanner and nuclear magnetic resonance, and radiation have led to more adapted treatment with fewer long term side effects than in the past. For more information on the various childhood and adolescent cancers: The department of childhood and adolescent cancer research at Gustave Roussy (Villejuif) has a dedicated site on which you can find a lot of information on the various types of cancer).