A recent analysis of the trends in 5-year cancer relative survival in the United States since 1975 shows how mortality has fallen for many types of cancer. However, relative survival continues to be substantially higher in white than black people.
Although still a major cause of death, cancer mortality in England is falling, and regional differences in mortality in the UK are also narrowing. A recent analysis of cancer mortality in the United States by Rebecca Siegel and colleagues shows that the 5-year relative survival of many cancers has also improved in that country, but that inequalities persist.
The first chart shows the trend in 5-year relative survival for cancers with low overall mortality, from 1975-77 to 2004-10, based on data from the SEER cancer database.
Over this time period, 5-year relative survival of all cancers increased from 49% in 1975-77 to 68% in 2004-2010, an absolute increase of 19%. The greatest improvement was seen in prostate cancer, with a 31% increase in relative survival, probably driven in part by greater detection of low-grade tumours from PSA screening, which would have been unlikely to cause death if undiagnosed.
Other cancers with low mortality that also showed more than 10% absolute improvement in survival include colon cancer and testicular cancer. However, and probably not surprisingly, most of the large improvements have been seen in cancers which still have a higher mortality, as shown in the chart below.
The chart shows that there has been a more than 20% increase in 5-year relative survival for cancer of the rectum, multiple myeloma, non-Hodgkin’s lymphoma and leukaemia. In contrast, there has been a slight decrease in relative survival for cancer of the endometrium and larynx, and very little improvement for cancer of the cervix or pancreas.
Siegel and colleagues also report how the 5-year relative survival trends have varied between white and black US residents. Overall, relative survival was 11% higher in whites than blacks in 1975-77, increasing to a 14% difference in 1987-89 but then falling to a 7% difference by 2004-10.
Looking at the cancers with lower mortality overall, the relative survival has been consistently higher in whites than blacks for each type of cancer, as shown in the chart below.
The greatest ethnic inequality in survival in this group is seen in endometrial cancer, malignant melanoma and bladder cancer, with an ethnic group difference of 20%, 18% and 16% respectively in 2004-10, and the lowest inequalities are found for prostate and rectal cancers, with an ethnic group difference of 1% and 5% respectively. Survival from breast cancer has remained between 12 and 14% higher in white than black women, and the gap has almost doubled for colon cancer, from 6% in 1975-77 to 11% in 2004-10.
In contrast, when those cancers with higher mortality are analysed, there are a small number of cancers where relative survival has been higher in black than white residents. However, even with these cancers, there has usually been greater improvement in survival in whites than in blacks. Cancer of the brain is now the only cancer where black people still have a survival advantage, with a 9% higher relative survival in blacks than whites. Survival from stomach cancer and multiple myeloma was higher in black than white people in the 1970s and 1980s, but is now similar in both ethnic groups, and the improvement in survival in non-Hodgkin’s lymphoma and ovarian cancer has been disproportionately in white rather than black adults.
Overall, the trends are encouraging. But, with little sign of decreasing inequalities between the ethnic groups, there is still considerable room for improvement.