Adolescence and Cancer

IntroductionCancer is the leading cause of death in adolescents. In the United States and most developed countries 2% of all invasive cancers are seen in ages 15-30 years. This number is 2.7 times higher than the number of cancers seen in children below 15 years of age. While the long term diseases free survival rates in children range between 70-90%, the improvement in the outcome for this age group has lagged behind (1). Limited access to care, poor adherence to treatment along with poor understanding of biology, in this age group may be responsible for poor outcome (2).Additionally limited emphasis on early detection such as routine testicular examination and inadequate healthcare coverage cause delay in diagnosis.This is further complicated by inability of adolescents to remain compliant with treatments. With the recognition of these barriers to care for adolescent and young adults with cancer the National Cancer Institute has formed separate sections of Adolescent and Young Adult (AYA) Cancer. The Children's Oncology group has the Adolescent and Young Adult (AYA) committee addressing the cancer related needs of these patients.Distribution of cancers in adolescent ages 15-19 years reported by SEER 1975-2000 is shown in table 1. Adolescent females are at higher risk for cancer than males and non-Hispanic white populations have the highest incidence of cancer in this age group.Etiology and risk factorsThe causes of cancer in adolescent are not known. Exposure to environmental carcinogens take a long time to develop and usually don't occur until later in life. In adolescence both genetics and environmental factors may play an important role.Melanoma after sun exposure is more common in Australian adolescents and points towards genetic predisposition. Clear cell carcinoma in adolescent girls is the result of exposure to diethylstilbestrol prenatally.Second malignant neoplasm may occur in adolescents after exposure to chemotherapy and/or radiation therapy in childhood.Diagnosis and treatmentThe clinical presentation of a cancer in adolescence is similar to the same cancer in another age group. Knowledge of presentation and distribution of cancers in this age group helps the clinician perform appropriate, yet thorough, physical examination, develop an appropriate differential diagnosis, request appropriate tests and referrals and follow patients after they have completed the treatments. Surgery is the main modality for diagnosis and treatment of solid tumors. Chemotherapy plays an important role in the treatment of lymphoma and leukemia and other cancers seen in adolescents. Cancer cells develop resistance against cytotoxic drug when used as single agent. Combination chemotherapy rather than single agent is used for the treatment of most cancers. Effective combination chemotherapy uses the following principles (3):* Each drug in the combination has some activity against the cancer as a single agent and the dose limiting toxicities of the agents used in the combination are different. For example, two nephrotoxic agents are seldom used together.* The drugs with different mechanism of action as well as resistance are combined.* Interaction of the drugs at the cellular level to provide best synergy is taken in to account to decide on the sequence and timing of administration of various cytotoxic agents the combination. For example S-phase specific drugs such as methotrexate are most effective during the periods of rebound DNA synthesis in recovery phase.With improved understanding of molecular defects and their association with a specific cancer potential genetic, targets have been identified and drugs are being developed to target the defect and to induce apoptosis. For example t(15;17) translocation in promyelocytic leukemia (PML) disrupts the function of retinoic acid receptor a (RARa). This type of PML responds well all trans-retinoic acid (ATRA). …