Credit: Bill Branson
A large, international study has revealed sizable differences in cancer survival rates between countries.
In particular, investigators observed a wide gap in survival for children with acute lymphoblastic leukemia (ALL).
The most recent 5-year survival rate was less than 60% in several countries—and as low as 16% in one nation—but more than 90% in other countries.
This indicates major deficiencies in managing this largely curable disease, according to researchers.
Results from this study, known as CONCORD-2, appear in The Lancet alongside a linked comment article.
Claudia Allemani, PhD, of the London School of Hygiene & Tropical Medicine in the UK, and her colleagues analyzed individual patient data from 279 cancer registries in 67 countries.
The team reported 5-year survival estimates for 25.7 million cancer patients diagnosed with 1 of 10 common cancers—stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, prostate, and leukemia (n=873,588)—from 1995 through 2009.
The investigators also reported survival estimates for 74,343 children diagnosed with ALL during that period.
Even after they adjusted for differences between countries and regions in the risk of death from other causes by age, sex, and race, and over time, the researchers found very large variations between countries in survival for specific cancers.
Adult leukemia
For adults diagnosed with leukemia from 2005 through 2009, the 5-year net survival was 50% to 60% in 21 countries in North America, west Asia, Europe, and Oceania. Survival rates were generally much lower in the 15 participating Asian countries than in other parts of the world.
Survival rates tended to be low in east Asia—ranging from 19% in Japan to 23% in South Korea and Taiwan—but higher in west Asia—ranging from 33% in Turkey to 53% in Qatar. And results were mixed in other Asian countries—ranging from 7% in Jordan to 40% in Indonesia.
ALL in children
For children diagnosed with ALL from 2005 through 2009, 5-year survival was 90% or higher in Austria, Belgium, Canada, Germany, and Norway. It was 80% to 89% in 21 countries on various continents.
However, 5-year survival was lower than 60% in several countries and the lowest—16%—in Jordan.
The range of survival estimates for childhood ALL in Central/South America and Asia was much lower than the range in North America, Europe, and Oceania.
Solid tumor malignancies
The study also showed that liver and lung cancer have the worst prognosis among the 10 cancers examined, with 5-year survival of less than 20% in both developed and developing countries. The researchers said this suggests most patients still visit their doctors too late for treatment to be effective.
Five-year survival from breast and colorectal cancers increased in most developed countries and in South America (Brazil, Colombia, and Ecuador) from the beginning of the study period to the end. These trends likely reflect earlier diagnosis and the availability of better treatment options, according to the investigators.
Stomach cancer survival was higher in Southeast Asia than in other regions. This is likely a result of intensive diagnostic activity, early stage at diagnosis, and radical surgery, the researchers said. And this suggests important lessons could be learned from these countries about diagnosis and treatment.
Cervical and ovarian cancers showed particularly wide differences in survival, and overall improvements during the study period were slight.
“Our findings show that, in some countries, cancer is far more lethal than in others,” Dr Allemani said. “In the 21st century, there should not be such a dramatic gulf in survival. The majority of the variability in survival is probably due to factors that can be changed, such as the availability and quality of diagnostic and treatment services.”
“The findings can be used to evaluate the extent to which investment in healthcare systems is improving their effectiveness. We expect them to act as a stimulus for politicians to improve health policy and invest in healthcare.”
