Data following up over 1 million cancer patients in the US between the years 1990 and 2010 have been analyzed to show that survival rates have improved by a substantially greater amount for younger patients than for elderly ones - and this age disparity "was most pronounced for cancers with the largest diagnosis and treatment advances during the study period, including colorectal, breast and prostate cancers," say the authors.
Their analysis, published online by JAMA Oncology, uses data on patients diagnosed with cancer of the colon or rectum, breast, prostate, lung, liver, pancreas or ovary from 1990 to 2009 who were included in registries of the National Cancer Institute Surveillance, Epidemiology and End Results (SEER) program.
No disparities in survival rates were found according to patients' race, except for a wider gap in ovarian cancer; and in prostate cancer, African-Americans fared better than white patients.
In one type of cancer, colorectal, the improvements in survival rates over time were almost four times less impressive for older patients. During the study period there was:
- An estimated 45% reduction in colorectal cancer-specific deaths among patients younger than 65 years
- Only a 12% reduction among those aged 75 to 85 years.
"A similar pattern of association was observed for breast, liver, lung, pancreatic and prostate cancers," say the authors.
The authors - led by Dr. Wei Zheng of the Vanderbilt Epidemiology Center and Vanderbilt-Ingram Cancer Center in Nashville, TN - also analyzed survival rates against specific cancer stage for colorectal and breast cancers. They discovered "a suggestion of greater differences in survival over time between younger and older age groups for localized and regional cancers than for advanced cancer."
These improvements were consistent with better surgical techniques and novel adjuvant treatments for patients with localized and locally advanced colorectal and breast cancers, but the advances do not seem to have helped older patients so much.
Where advances in cancer care have not been so great overall, there has also been less of an age-disparity. The authors found:
"Among patients with liver, lung, pancreatic or ovarian cancer, for which treatment improvements have been modest, the gap in improved survival between younger and older patients was also less evident."
Risk of death from cancer was calculated for a diagnosis between 1990 and 1994, and compared with that for a diagnosis between 2005 and 2009.
For patients aged 50 to 64 years, the reductions in death risk over the 20 years were:
- 39% for liver cancer
- 68% for prostate cancer.
For patients diagnosed between the ages of 75 and 85 years, however, improvements in survival over time were much lower:
- 24% fall in death rate for patients with liver cancer
- 35% fall for prostate cancer.
"Our data suggest that age- and race-related differences in survival improvements over time may be explained, at last in part, by differences in cancer care across these subpopulations," the authors conclude.
The researchers believe they have made an "initial step toward acknowledging the possibility of differential care and/or responses to new therapies for different patients." They blame a lack of evidence from study subpopulations for the disparities, and want better research on these.
The authors conclude that their findings are a "call to action." Future research must try more to include the elderly and African-Americans in their diverse study populations, "in order to establish an evidence base for treatment of all patients."
The paper concludes: "Understanding differences in the rates of improvement in survival among these specific populations and addressing these differences in future studies is a crucial part of improving cancer care for all."
Researchers publishing in the journal Cancer last week said they had identified 8 signs shown by cancer patients that were associated with death within 3 days, enabling, they said, better care plans to be implemented.