Are Cancers genetic (hereditary) or environmental in origin?
After sequencing his own genome, pioneer genomic researcher Craig Venter remarked, “Human biology is actually far more complicated than we imagine. Genes are absolutely not our fate. They can give us useful information about the increased risk of a disease, but in most cases they will not determine the actual cause of the disease, or the actual incidence of somebody getting it. Most biology will come from the complex interaction of all the proteins and cells working with environmental factors, not driven directly by the genetic code.”
The fact is, only 5–10% of all cancer cases can be attributed to genetic defects, whereas the remaining 90–95% have their roots in the environment and lifestyle(Fig. 1). The lifestyle factors include tobacco intake, cigarette smoking, diet (fried foods, red meat), alcohol, environmental pollutants, infections, stress, obesity, and physical inactivity and sun exposure. The evidence indicates that of all cancer-related deaths, almost 25–30% are due to tobacco, as many as 30–35% are linked to diet, about 15–20% are due to infections, and the remaining percentage are due to other factors like radiation, stress, physical activity, environmental pollutants etc. Therefore, cancer prevention requires tobacco abstinence, increased ingestion of fruits and vegetables, limited use of alcohol, caloric restriction, exercise, avoidance of direct exposure to sunlight, minimal meat consumption, use of whole grains, use of vaccinations, and regular health check-ups.
Cancer is caused by both internal factors (such as inherited mutations, hormones, and immune conditions) and environmental/acquired factors (such as tobacco, diet, radiation, and infectious organisms.