those diagnosed in 1991–1992, to 667 days for those diagnosed in 1999–2001. An assessment by Health Canada found that cancer mortality rates are almost identical in the two countries. Another international comparison by the National Cancer Institute of Canada indicated that incidence rates for most, but not all, cancers were higher in the U.S. than in Canada during the period studied (1993–1997). Incidence rates for certain types, such as colorectal and stomach cancer, were actually higher in Canada than in the U.S. In 2004, researchers published a study comparing health outcomes in the Anglo countries. Their analysis indicates that Canada has greater survival rates for both colorectal cancer and childhood leukemia, while the United States has greater survival rates for Non-Hodgkin's lymphoma as well as breast and cervical cancer. A study based on data from 1978 through 1986 found very similar survival rates in both the United States and in Canada. However, a study based on data from 1993 through 1997 found lower cancer survival rates among Canadians than among Americans. A few comparative studies have found that cancer survival rates vary more widely among different populations in the U.S. than they do in Canada. Mackillop and colleagues compared cancer survival rates in Ontario and the U.S. They found that cancer survival was more strongly correlated with socio-economic class in the U.S. than in Ontario. Furthermore, they found that the American survival advantage in the four highest quintiles was statistically significant. They strongly suspected that the difference due to prostate cancer was a result of greater detection of asymptomatic cases in the U.S. Their data indicates that neglecting the prostate cancer data reduces the American advantage in the four highest quintiles and gives Canada a statistically significant advantage in the lowest quintile. Similarly, they believe differences in screening mammography may explain part of the American advantage in breast cancer. Exclusion of breast and prostate cancer data results in very similar survival rates for both countries. Hsing et al. found that prostate cancer mortality incidence rate ratios were lower among U.S. whites than among any of the nationalities included in their study, including Canadians. U.S. African Americans in the study had lower rates than any group except for Canadians and U.S. whites. Echoing the concerns of Dr. Kramer and Professor Mackillop, Hsing later wrote that reported prostate cancer incidence depends on screening. Among whites in the U.S., the death rate for