The estimated population of the world in 2008 was 6.75 billion people, increasing by around 79 million people each year. The world population is aging. In 1970, the world median age was 22 years; it is projected to reach 38 years by 2050. The number of people in the world aged 60 years and older is expected to almost triple to 2 billion by 2050. Because cancer, especially prostate cancer, is predominantly a disease of the elderly, increases in the number of older people will lead to more cases of cancer, even if current incidence rates remain the same.