Unlike infections, cancer is not caused by one specific thing. Links are often made between a genetic or behavioral factor and cancer, but these links are only one step in understanding why people get cancer. Cancer is usually not caused by one thing, but several things which work together to create a tumor. In most cases, it takes years of exposure before cancer appears. This is one reasons most cancers appear in older individuals.

Through many years of studies, cancer research was able to find a link between smoking and lung cancer. While about 85% of lung cancer is tobacco related, other factors, like genetics, play a role in deciding whether a person gets lung cancer.

Cancer research studies have been less successful in identifying causes of some other cancers like prostate cancer. While researchers believe that diet and genetics may play a role in the abnormal cell growth process, they have not discovered a direct link between these two factors as was found between lung cancer and tobacco.

Breast cancer researchers have been able to identify numerous possible causes for the development of tumors of the breast. While breast cancer researchers have been able to find a gene that makes people more susceptible to breast and ovarian cancer, only about 5% of breast cancer cases can be linked to these genes. The other 95% may be linked to environmental toxins, alcohol intake, hormonal birth control and childbearing.

As new cancer research continues to find possible causes and treatments, it is important to remember that every cancer is different. Researchers will not find one single cure or treatment. Instead, research efforts are focused on prevention and treatment techniques for each type of cancer.