Controllable and uncontrollable factors often coincide to a point where it is impossible to determine the exact cause of a cancer. There are other factors that are often considered potential causes but have not been scientifically proven. Among the most common are:

• Electromagnetic fields. Some people believe that living near power lines and electromagnetic fields can increase the risk of cancer, especially in children. Studies thus far have reached inconclusive and oftentimes inconsistent results. In addition, cordless and cellular telephones have been under scrutiny as a possible cause for cancer, particularly brain cancers. However, because this technology has not been in use for an extended length of time, there has not been ample opportunity to conduct long-term studies. Current studies have not proven a definitive association between cell phone use and brain tumors.
  
  
• Psychological stress. There is a complex relationship between physical and psychological health and it is not completely understood. Scientists acknowledge that stress can activate the body’s endocrine (hormone) system, which can lead to immune system changes. Immune system changes make the body less able to fight infection and diseases. Still, a direct link has yet to be established between stress and cancer. While studies have shown that stress factors alter the immune system, no direct cause-and-effect relationship has been established.
  
  
• Toxic waste. The toxic chemicals and substances in dump sites and waste areas have been studied for causal relationship to cancer. Although many of the substances can be hazardous to people’s health, studies have not proven their exact role in causing cancers.
  

There is a considerable amount of research being devoted to the relationship between elements found in people’s daily lives and cancer. Scientists continue to examine many areas in an attempt to discover possible contributions and causes of the disease.