The number one health challenge facing the world today is cancer.
Its occurrence has been increasing due to environmental deterioration and increased exposure to chemicals and radiation.
Cancer is closely followed by diabetes as the world's population is getting fatter and fatter. Diabetes is often cause by obesity which became a growing epidemic in the 21st century, especially in developed countries.
The next challenge are heart diseases caused by smoking, high-fat diet, lack of exercise and sedentary lifestyle.
The remaining challenges are: kidney disease, Alzheimer's disease, influenza, stroke and AIDS.