Cancer is a disease in which cells begin to grow abnormally in a particular tissue or organ, which can eventually disrupt the body's ability to function properly. Cancer has more than 100 different variations and can occur in nearly any type of cell, including the skin, tissues, organs, and blood. Many cancers can also spread, or metastasize, to other parts of the body. Cancer risk is influenced by several factors, such as nutrition, environment, physical activity, and genetics. Males are roughly 20% more likely than females to contract cancer and have higher cancer rates than women in almost every type of cancer. Cancer is the second leading cause of death in the world, behind only cardiovascular disease. It is estimated that every sixth death in the world is due to cancer.
Cancer tends to be more prevalent in high-income countries due to lifestyle factors such as smoking, obesity, and alcohol intake. Fortunately, these also tend to be countries with sound health care systems, which can better detect and treat cancer than the health-care systems in low-income countries. Moreover, advancements in medical knowledge and technology continue to improve each country's cancer survival rate. Although a decreasing percentage of cancer patients succumb to the disease, the total number of deaths from cancer continues to rise. This is often attributed to the fact that the world's ever-growing population includes more senior citizens, whose cancer risk is highest, than ever before. Cancer rates are typically expressed as a crude rate or as an age-standardized rate, which adjusts for the fact that some countries' populations are younger overall than others.
Top 10 Countries with the Highest Cancer Rates (2020 Age-Standardized Rates per 100k, WHO)
Australia has the world's highest age-standardized cancer rate at 452.4 cases per 100,000 people. Australia has some of the highest rates of breast cancer and melanoma in the world. New Zealand (745.2) and Ireland (645.1) rank second and third. On the other end of the chart, Niger has the lowest ASR cancer rate in the world at just 40.4 cases per 100,000 people, with the Gambia (42.8) and Nepal (70.4) close behind. However, it is also important to remember that these numbers estimate cancers that have been detected, not total cases in existence. It is likely that case tallies in underdeveloped countries such as Niger, Gambia, and Nepal are suppressed by the fact that many people lack access to adequate health care, thus their cancers are going undiagnosed.