Breast cancer rated 15,5% of cancer deaths

Breast cancer has exceeded lung cancer as the most commonly diagnosed cancer.

07 October 2021 | Health

Breast cancer is the fifth higest cause of cancer deaths in the world, with an estimated 2.3 million cases and 685,000 deaths in 2020.

The cases are expected to reach 4,4 million in 2070. Among women, breast cancer accounted for approximately 24,5% of all cancer cases and 15,5% of cancer deaths, ranking first for incidence and mortality in the majority of the world countries in 2020.

The main risk factors for breast cancer are older age, high body mass index or obesity, exposure to tobacco, physical inactivity, high fat dietary, early age menarche, late age at first full-term pregnancy, shorter breastfeeding periods, use of hormonal menopausal therapy or oral contraceptives, breast density and family history of breast cancer.

Elevated incidence rates of breast cancer may reflect increased prevalence of risk factors, opportunistic or organized mammography screening detections, aging, and growth of population. However, the difference in major risk factors, screening strategies, and population size or structures of different regions led to the disparities in the burden of breast cancer.

For example, obesity is an important determinant contributing to breast cancer incidence. The prevalence of obesity had remarkable regional differences and ranged from 3.7% in Japan to 38.2% in the United States of America (USA) in 2015. In highly developed countries, such as the United Kingdom, the Netherlands, the USA, more extensive use of mammography screening has been one of the main reasons for the high incidence of breast cancer since the 1980s.

Nevertheless, some African and Asian countries had relatively low breast cancer incidence but showed rapidly increasing trends due to changes in social economic development and lifestyle. In addition, the diagnosed age of breast cancer was also distinct among different world regions. Western countries had later onset age of breast cancer compared with some Asian countries.

Previous studies have only focused on the comparison of breast cancer burden between world regions or the description in one country. The burden of breast cancer and the summit age of diagnosis have not been well assessed between countries based on the 20 world areas.

Herein, the aim of this study was to describe and compare the incidence and mortality rates of female breast cancer in specific countries across 20 world regions in 2020 by using the most up-to-date data, and analyze the temporal trends of incidence and mortality in major countries to provide valuable information for breast cancer prevention and control.

An estimated 2.3 million females were diagnosed with breast cancer in 2020, accounting for approximately 24,5% of all cancer cases worldwide. The crude and age-standardized incidence rates of breast cancer were 58,5 and 47.8 per 100,000 population.

Of the different countries, China had the largest number of breast cancer cases, accounting for approximately 18,4% of global breast cancer cases, followed by the USA, with 1,8% breast cancer cases in the world. The age-standardized incidence rates among countries varied over 3-fold, from 113,2 per 100 000 population in Belgium to 35,8 per 100,000 population in Iran.

Highly developed countries (Belgium, Demark, Australia, USA, United Kingdom, and Italy) had much higher incidence rates than the world age-standardized incidence rates (47,8 per 100 000 population), while developing countries (Iran, China, Mexico, Cameroon, and Costa Rica) had lower incidence rates than the world age-standardized incidence rates.

The age-specific incidence rates of breast cancer were relatively low for female < 25 years old in all countries investigated and increased dramatically after this age. Remarkably, the peak age of breast cancer varied across the world regions. South Korea and Cameroon had the youngest onset peak age of 40 years old. China, Japan, Iran, Fiji, Morocco peaked among female aged 55-60 years old. The summit onset age of breast cancer in the USA, Belgium, Australia, and the United Kingdom were latest with age of 70 years.

There were approximately 685 000 females who died from breast cancer in 2020, accounting for approximately 15.5% of all cancer deaths in the world. The crude and age-standardized mortality rates of breast cancer were 17,7 and 13,6 per 100 000 population globally.

Similar to the large number of breast cancer cases, China had the largest number of breast cancer deaths, accounting for approximately 17,1% of all cancer deaths, followed by the USA, which accounted for 6,2% of breast cancer deaths in the world. The age-standardized mortality rates across countries varied greatly (nearly 7-fold), from 41 per 100,000 in Fiji to 6,4 per 100 000 in South Korea.

In contrast with the incidence rates, high mortality rates occurred in most undeveloped or developing countries (e.g. Fiji, Jamaica, Samoa, Nigeria, Cameroon), whereas high-income countries (e.g. South Korea, Japan, and the USA) had lower mortality rates.

The age-specific mortality rates of breast cancer increased with the age and reached the highest in age = 70 among most of the countries examined. Source: