Genetic & Environmental Factors that Influence Brain Cancer

1) What is the approximate heritability of brain cancer?
The heritability of brain cancers is extremely low and not precisely established. An informed estimation might suggest that the heritability is approximately 0.01 (less than 1%). Most cases of brain cancer are not inherited, although research is leading towards evidence that some genes causes susceptibility to cancer. Hereditary cancer syndrome is caused by a inherited gene mutation. If you inherit this mutation, your chances of developing this cancer increase. If multiple generations are affected by the same cancer, it is likely that those members have hereditary cancer syndrome. Overall, cancer is a highly multifactorial condition determined by genetic and environmental factors, although very little is definitively known about this disease.


2) What environmental factors influence this disease?
There are only a few well-established environmental influences that lead to the development of brain cancer. In a National Cancer Institute (NCI) study, researchers noted that people who have received high-dose ionizing radiation to the head during childhood have an increased risk of developing brain cancer. This type of radiotherapy includes exposure to gamma or X-rays. Aside from the small percentage linked to radiation exposure, few other risks have been determined. In the same study, NCI stated that there was "no evidence of higher brain tumor risk among people who use hand-held cellular phones compared to those who do not use them." The idea that cell phone use causes brain cancer is a myth.
According to numerous sources, another environmental factor that has been shown to contribute to brain cancer is vinyl chloride. This is a chemical found in plastic products and tobacco smoke.

Sources:
http://www.cancer.gov/cancertopics/factsheet/risk/brain-tumor-study
http://www.accessdna.com/condition/Brain_Cancer/67