Globally, the number of new cancer patients each year is expected to rise from 18m in 2023 in a population of 8bn people to 35m by 2050 in a population of 10bn people – a 77% increase. This is primarily due to the aging of the population since the risk of cancer increases considerably with age. Also, as life expectancy increases globally, more people will live long enough to develop cancer. The increase in cancer incidence may be more pronounced in developing countries. This is partly due to these countries undergoing rapid societal and economic changes, leading to lifestyle patterns (such as diet, physical activity, and tobacco use) that are associated with higher cancer risk. Additionally, these regions are experiencing improvements in healthcare infrastructure and access, leading to better detection and reporting. Even if dramatic lifestyle changes occurred immediately, it would take many years for any change to be reflected in the overall cancer burden. The numbers are simply locked into our future, certainly over a 25-year span.

Impact of lifestyle and environmental factors:

Changes in lifestyle, such as increased consumption of processed foods, physical exercise, alcohol use and obesity profoundly affect the epidemiology of cancer. Unfortunately, there is not enough information to predict specific annual changes in the number of cancer patients by world region. Some general points:

Growth rates of cancer incidence will likely differ significantly across regions based on population aging, adoption of unhealthy lifestyles, early detection capacities and case notification. Developed regions may see slower increases in annual cases with population stabilization, but with a higher cost of treatment per case. Lower-middle income regions could see rapid rises in new cases given growing and aging populations.

While a global rise of 77% in new cancer cases by 2050 is widely predicted, the specific annual changes for different world regions are more nuanced and depend on various factors. Here's a breakdown of what we know:

Overall Trends

• Africa: The fastest-growing cancer burden, potentially more than doubling by 2050 due to increasing population and urbanization.
• Asia: Expected to face the highest absolute number of new cases due to its large population, although the annual increase might be lower than Africa.
• Latin America and the Caribbean: A projected moderate increase, influenced by aging populations and lifestyle changes.
• Europe and North America: Slower increase due to already advanced healthcare systems and stabilizing populations, though still significant due to aging populations.
• Oceania: The smallest increase due to a low and slow-growing population, but still facing challenges due to existing disparities in access to healthcare.

Regional variation: The annual changes will vary based on the types of cancer prevalent in each region. For example, lung cancer might show a higher increase in areas with high smoking rates, while physical inactivity, and the ongoing high rates of smoking in certain regions, can lead to an increase in certain types of cancers. Environmental factors, including pollution and exposure to carcinogens, also play a smaller but significant role.

In regions with robust cancer screening and prevention programs, there might be an initial increase in reported cancer cases due to improved detection. Over time, however, these programmes can lead to a decrease in certain types of cancers, as seen with cervical cancer and the impact of HPV vaccination. The types of cancers that are most prevalent can vary by region due to genetic, environmental, and lifestyle factors. For instance, gastric cancer is more common in East Asia, while colorectal cancer rates are much higher in Western countries.

The COVID-19 pandemic has led to delays in diagnosis that cannot reliably be predicted in different healthcare systems. Income level, healthcare access, and lifestyle choices significantly impact cancer incidence. Low-middle income countries will face steeper increases due to limited awareness, prevention resources, and treatment options. Regions with a rapidly aging population, like Europe and parts of Asia, will likely see a bigger rise in incidence due to the increased risk associated with age.