Cancer survival rates vary by the type of cancer, stage at diagnosis, treatment given and many other factors, including country. In general survival rates are improving, although more so for some cancers than others. Survival rate can be measured in several ways, median life expectancy having advantages over others in terms of meaning for people involved, rather than as an epidemiological measure. However, survival rates are currently often measured in terms of 5-year survival rates, which is the percentage of people who live at least five years after being diagnosed with cancer, and relative survival rates compare people with cancer to people in the overall population. Several types of cancer are associated with high survival rates, including breast, prostate, testicular and colon cancer. Brain and pancreatic cancers have much lower median survival rates which have not improved as dramatically over the last forty years. Indeed, pancreatic cancer has one of the worst survival rates of all cancers. Small cell lung cancer has a five-year survival rate of 4% according to Cancer Centers of America's Website. The American Cancer Society reports 5-year relative survival rates of over 70% for women with stage 0-III breast cancer with a 5-year relative survival rate close to 100% for women with stage 0 or stage I breast cancer. The 5-year relative survival rate drops to 22% for women with stage IV (metastatic) breast cancer. In cancer types with high survival rates, incidence is usually higher in the developed world, where longevity is also greater. Cancers with lower survival rates are more common in developing countries. The highest cancer survival rates are in countries such as South Korea, Japan, Israel, Australia, and the United States. Survival rate trends In the United States there has been an increase in the 5-year relative survival rate between people diagnosed with cancer in 1975-1977 (48.9%) and people diagnosed with cancer in 2007-2013 (69.2%); these figures coincide with a 20% decrease in cancer mortality from 1950 to 2014. Due to innovation in emerging treatments and cancer prevention strategies, the U.S.A cancer death rate has declined from 208.3 per 100,000 people in 1982 to 152.6 per 100,000 in 2017. Lung cancer In males, researchers suggest that the overall reduction in cancer death rates is due in large part to a reduction in tobacco use over the last half century, estimating that the reduction in lung cancer caused by tobacco smoking accounts for