Cause of cancer usually can not be known with certainty because it can cause cancer is a combination of a set of factors, genetic and environmental, that increase the risk of cancer. There are some cancers that are known causes
Descendants of factors
Genetic factors cause some families have a higher risk for certain cancers when compared with other families. For example, women's risk for breast cancer increased by 1.5 to 3 times when her mother or sister had breast cancer.
Some breast cancer associated with a specific genetic mutation, which is more common in some ethnic groups and families. Women with mutations in this gene have a chance of 80% -90% for breast cancer, and 40% -50% for ovarian cancer. Other cancer tends to run in the family is skin cancer and colon cancer.