Final answer:
Childhood cancer is rare with leukemia being the most common type among children. Cancer is mostly diagnosed in older adults and is often related to a combination of genetic and environmental factors, with some proportion being highly genetically influenced. The leading causes of death in children under five in low-income countries are primarily due to preventable diseases, not cancer.
Step-by-step explanation:
The natural incidence of fatal childhood cancer is considered to be rare. Childhood cancer accounts for a small percentage of overall cancer cases, with leukemia being the most common type of cancer in children, constituting about one third of all pediatric cancer. While cancer is one of the leading causes of death worldwide, in children under five, especially in low-income countries, the most frequent causes of death include pneumonia, diarrhea, and congenital anomalies, among others; cancer does not top this list.
It is important to note that cancer is a diverse group of diseases characterized by abnormal cell growth with the potential to invade or spread. The majority of cancers occur in adults over 65 years of age, and most are attributed to a combination of genetic and environmental factors, with about 10% strongly tied to genetic predispositions.
The risk of cancer can increase with exposure to radiation, and there is a latency period for the onset of radiation-induced cancer which varies depending on the type of cancer. However, the incidence of genetic defects induced by radiation is about one-third that of cancer deaths.