Although breast cancer is the most common cancer in the female population worldwide, there is a significant difference in the prevalence of this cancer in the world.

As a general principle, this cancer is more common in developed countries than in developing countries, and is more common in urban areas than rural areas. Evidence suggests that if women migrate from developing countries with lower prevalence to developed countries, after two generations the prevalence of these women will be similar to that of women in developed countries. This evidence supports the influence of environmental factors on the development of this cancer. The important point is that every year about one and a half million people around the world get this cancer.

Although the prevalence of cancer in developing countries is much lower than in developed countries, due to the high population of these countries, the majority of breast cancer cases are seen in developing countries. In addition, according to the World Health Organization in 2012, out of about 700,700 total cancers registered in 2008, about 6 million were lung cancers of the two sexes, but more than 5 million were breast cancers. But the interesting point is that despite this high prevalence, 89% of breast cancer cases have a lifespan of 5 years, and therefore most of the cancer survivors are breast cancer patients.

The same study shows that the prevalence of cancer varies from at least 92 per 100,000 population in Central Africa to 313 in New Zealand and 300 in the United States per 100,000 population. However, depending on the location of breast cancer, about 10-15% of all cancers in the general population or 20-30% of all female cancers. Asia is the most populous continent due to the presence of China and India and has the highest number of breast cancers and Africa has the lowest rate of breast cancer.

Due to the difference in the quality of diagnosis and treatment of this cancer in developing countries compared to developed countries, the highest mortality rate of this cancer is seen in these countries.