Cancers of the gastrointestinal tract represented about one in four cancer cases in 2018 but more than one in three cancer-related deaths, underscoring the importance of preventive measures, according to an analysis of global cancer datasets that identified trends in five major GI cancer types – esophageal, stomach, colorectal, liver, and pancreatic – published in Gastroenterology.
“Although the incidence of some GI cancer types has decreased, this group of malignancies continues to pose major challenges to public health,” wrote Melina Arnold, PhD, of the International for Research on Cancer in Lyon, France, and colleagues. “Primary and secondary prevention measures are important for controlling these malignancies – most importantly, reducing consumption of tobacco and alcohol, obesity control, immunizing populations against hepatitis B virus infection, and screening for colorectal cancer.”
For example, the study found that the proportion of GI cancer deaths in Asia exceeds that of new cases, with the greatest disparity in China, while the opposite can be said of GI cancer trends in Europe and North America.
The study reported 4.8 million new cases of GI cancer and 3.4 million deaths worldwide in 2018. GI cancers accounted for 26% of the global cancer burden but 35% of cancer-related deaths. Incidence-to-death disparities were greatest for Africa, accounting for 4% of new cases and 5% of deaths; and Asia, with about 63% of new cases but 65% of deaths. The disparity was even wider in China, which accounted for 38% of worldwide cases but 41% of the deaths. Europe and North America, on the other hand, accounted for 26% of global cases but 23% of deaths. High death rates of these cancers are associated with late detection, Dr. Arnold and colleagues noted.
Regarding the five different types of GI cancer, the study reported the following:
- Esophageal cancer accounted for 572,000 new cases and 508,000 deaths in 2018, making it the sixth-most-deadly cancer worldwide. Rates in men are two to three times higher than in women. Eastern Asia has the highest rates, 12.2 per 100,000 person-years, followed by eastern Africa (8.3) and southern Africa (7.4). China alone accounts for 54% of the global burden. A large percentage of these cancers in developing countries are squamous cell carcinoma, the most common form of esophageal cancer globally, which has been linked to tobacco use, heavy alcohol consumption, opium intake, air pollution, and diet.
- Gastric cancer accounted for more than 1 million new cases and nearly 800,000 deaths in 2018. Again, the incidence is twice as high in men as in women, and eastern Asia has the highest rates of 22 per 100,000 vs. < 5 in Africa, North America, and northern Europe. Cardia gastric cancer (CGC), associated with obesity and gastroesophageal reflux disease, is more prevalent in Western countries, while noncardia gastric cancer (CG) is more prevalent in countries with higher rates of Helicobacter pylori infection. In the United States specifically, CGC is more common in non-Hispanic whites than other ethnic groups. Gastric cancer rates have been declining in recent years, although trends of CGC and cancer of the gastric corpus, which the study terms “a noncardia subsite,” among younger people “may lead to a deceleration or a reversal” of declining gastric cancer rates, stated Dr. Arnold and colleagues.
- Colorectal cancer remained the most commonly diagnosed GI cancer in 2018, accounting for 1.8 million cases and 881,000 deaths, which represents 1 in 10 cancer deaths. The highest incidence was found in Australia/New Zealand, the lowest in south and central Asia. Colorectal cancers are in “transition” from infection-related cancers to those related to “rapid societal and economic change.” Dr. Arnold and colleagues attributed these changes to higher dietary intake of fats, sugar, and animal-source foods and increases in sedentary behavior and obesity. Despite advances in cures for colorectal cancer, disparities continue, even in high-income countries, and screening programs have been limited, according to the study. Colorectal cancer will be “one of the main contributors” to the doubling of cancer rates in older adults by 2035.
- Liver cancer comprised 841,000 cases and 782,000 deaths in 2018, making it the sixth-most-diagnosed cancer but the fourth most deadly. “Transitioning countries” in eastern Asia, Micronesia, and northern Africa have the highest rates. In eastern Asia, hepatitis B infections and aflatoxins are the primary risk factors for hepatocellular carcinoma, while in Japan and Europe hepatitis C is the main cause for hepatocellular carcinoma. Decreases in both infections and aflatoxins may explain declines in liver cancer rates in those regions. Whereas in lower-risk areas, increasing liver cancer rates caused by more widespread obesity and diabetes may be offsetting declines in HBV and HCV rates.
- Pancreatic cancer was the 12th-most-common cancer but the seventh leading cause of cancer death, with 432,000 cases and 459,000 deaths in 2018. Wealthy countries have incidence and death rates three to four times higher than do less-developed countries, with rates highest in Europe, North America, and Australia/New Zealand. Because pancreatic cancer isn’t typically diagnosed until it is in the metastatic or locally advanced state, curative surgery isn’t feasible, Dr. Arnold and colleagues stated. Population aging and growth, along with advances in treating other types of cancers, mean that pancreatic cancer “has become or is set out to become one of the leading causes of cancer-related death in many countries,” Dr. Arnold and colleagues stated. They added that, in the European Union, pancreatic cancer is already the third-leading cause of cancer death after lung and colorectal cancer.
The findings, Dr. Arnold and colleagues wrote, underscore the shift of the cancer burden toward transitioning countries, “which are less equipped to manage this increasing burden.” In the United States, the rates of all five GI cancers in young adults (aged 25-49 years) have increased.
GI cancers, with the exception of colorectal cancers, also contribute disproportionately to cancer-related death rates, mostly because all but colorectal cancers are difficult to diagnose.
However, early detection and screening programs for gastric cancer in Japan and Korea, and esophageal cancer in China “have shown promising results,” Dr. Arnold and colleagues said. “Pancreatic cancer, on the other hand, is becoming a more important contributor to cancer-related mortality as a consequence of improved diagnosis and management of the historically most common forms of cancer death,” they wrote.
Prevention remains key, and lifestyle choices like smoking, alcohol intake, and physical activity are all drivers of GI cancer burden. “Primary and secondary prevention measures remain the most important tools to control this group of malignancies, particularly in light of their preventability and often dreadful prognosis,” Dr. Arnold and colleagues wrote.
Dr. Arnold and colleagues have no financial relationships to disclose.
SOURCE: Arnold M et al. Gastroenterology. 2020 Apr 2;S0016-5085(20)30452-2. doi: 10.1053/j.gastro.2020.02.068.