Data for this study came from 101 population-based registries in 31 countries on five continents. The researchers utilized data on almost 2 million cancer patients in order to compare 5-year survival for cancers of the breast (women), colon, rectum and prostate. In some of the countries (16 of 31), the entire national population was included in the data, and almost 300 million people were covered by the cancer registries. Patients included were those who received a cancer diagnosis between 1990 and 1994; they were followed up until the end of 1999. Due to wide international differences in death rates in the general population, the researchers adjusted the data for factors such as background mortality and age.
In the international comparison, the researchers saw the highest survival rates for breast and prostate cancer in the USA. They also noted Japan as having the highest survival for colon and rectal cancers in men and France as having the highest survival for colon and rectal cancers in women. Canada and Australia also ranked relatively high for most cancers, while Algeria clearly claimed the lowest survival for all cancers in both men and women.
The within-country comparison for the USA included 16 states and metropolitan areas. Wyoming had the worst survival for rectal cancer in women, but New York City had the lowest survival rates for all of the other studied cancers. Hawaii had the highest survival rates for all cancers studied with two exceptions: Idaho led survival for rectal cancer in men and Seattle, WA led survival for prostate cancer. Whites and blacks in the USA saw differences in cancer survival between 7 and 14% - favoring whites. Specifically, white women had a 14% higher survival for breast cancer than black women, and white men had a 7% higher survival for prostate cancer than black men. What are the reasons for these racial disparities? The researchers suggest that white and black people receive diagnoses in different stages of the disease, have unequal access to health care, and are different in complying with treatment.
For all cancers, Europe had a much lower survival than the US. Survival for prostate cancer in the US is 91.9% compared to 57.1% in Europe - a 34% difference. The difference for breast cancer survival, however, is 10%. In Europe, the western countries generally had higher cancer survival rates: France led survival for rectum and colon cancers, Sweden led for breast cancer (82%), and Austria led for prostate cancer. Eastern Europe, on the other hand, did not perform as well. Slovakia had the lowest survival rates for rectal cancer in men and breast cancer, and Poland had the lowest survival rates for the other studied cancers.
For this study, the researchers divided the UK into four countries: England, Scotland, Wales, and Northern Ireland. Wales saw the lowest 5-year survival for all cancers in the UK. Scotland had the highest survival rates for rectal cancer in women and prostate cancer, while Northern Ireland had the highest for the others. The general trend in cancer survival in the UK, from highest to lowest, was Northern Ireland, Scotland, England, Wales. This held for all cancers except rectal cancer in women and prostate cancer. Differences in survival rates were not as large as in continental Europe, but still ranged from 5.0% in rectal cancer for women (between Scotland and Wales) to 11.0% for colon cancer in women (between Northern Ireland and Wales).
England was also analyzed separately, and the researchers found that the Trent region had the lowest survival for all cancers studied. The West Midlands had the highest survival rates for breast cancer and colon cancer in men and women, East Anglia led for rectal cancer in men, the south west led for rectal cancer in women and cancer of the colon and rectum overall in both men and women, and the south Thames region had the highest survival rates for prostate cancer.
In Australia, the Northern Territory had the worst survival rates for breast and prostate cancers, and the state of Tasmania had the worst survival rates for all other studied cancers. The Northern Territory, however, had the highest survival rate for rectal cancer in women, and the highest survival rates for the other cancers were spread around the rest of Australia. Overall, high standards of care were responsible for very high survival rates in Australia and Canada. In addition, there was little variation in survival between Australia's states and territories and between Canada's provinces. Compared to these two countries, geographic variation was much wider between Europe's countries and between the states of America.
"Most of the wide global range in survival is probably attributable to differences in access to diagnostic and treatment services. International variation in survival in Europe has been associated with national levels of economic development, as measured by total national expenditure on health. Survival is positively associated with gross domestic product and the amount of investment in health technology such as CT scanners. Part of the international variation in survival is thus probably attributable to under-investment in health resources," conclude the authors. More research is required to see if these international variations can be explained by differences in stage at diagnosis and treatment.
Cancer survival in five continents: a worldwide population-based study (CONCORD)
Michel P Coleman, Manuela Quaresma, Franco Berrino, Jean-Michel Lutz, Roberta De Angelis, Riccardo Capocaccia, Paolo Baili, Bernard Rachet, Gemma Gatta, Timo Hakulinen, Andrea Micheli, Milena Sant, Hannah K Weir, J Mark Elwood, Hideaki Tsukuma, Sergio Koifman, Gulnar Azevedo e Silva, Silvia Francisci, Mariano Santaquilani, Arduino Verdecchia, Hans H Storm, John L Young, and the CONCORD Working Group
The Lancet Oncology (2008).