Abstract
Objectives: This study aimed to estimate the long-term trends of breast cancer incidence in Shanghai, Hong Kong, and Los Angeles (LA). Methods: Data were obtained from Cancer Incidence in Five Continents (CI5plus) database. The average annual percent change (AAPC) was conducted by joinpoint regression analysis, and the age, period and cohort effects were estimated by age-period-cohort (APC) analysis. Results: The age-standardized incidence rates (ASIRs) in LA were higher than Shanghai and Hong Kong. During 1988–2012, the ASIRs significantly decreased in white women in LA (AAPC = −0.6%, 95% CI: −0.9% to −0.4%) while increased in Shanghai (2.5%: 2.1%–2.9%) and Hong Kong (2.2%: 2.0%–2.5%). The APC analysis revealed significantly increased effects of age and period, and decreased effect of birth cohort. Conclusion: Although age and cohort effects were relatively strong, the period effect may be the key factor affecting trends of incidence, which may be caused by increasing exposures to carcinogens and risk factors. Therefore, more effective measures should be carried out promptly to protect high-risk populations such as elder women, to avoid exposures to risk factors of breast cancer.
Highlights
Cancer has been recognized the major threat to health globally, which caused a total of 4.11 million deaths in 2017 [1]
Considering that the different cities in largest countries have substantial disparities in the influencing factors on breast cancer, such as economic development, health systems and environment, and so on, the present study aimed to investigate the historical trends of breast cancer incidences in Shanghai and Hong Kong in China compared with Los Angeles (LA) in the United States to explore the more specific causes of the potential risks, thereby to give hints on resource allocation targeting vulnerable groups for the prevention of breast cancer, as well as provide certain etiologic implications on breast cancer incidence for different cities
Data were extracted from Cancer Incidence in Five Continents (CI5plus) database, which provide annual incidence cases and rates for 28 major cancer types in 124 selected populations from 108 cancer registries, and the incidence accuracy was relied on the local registries [15,16,17]
Summary
Cancer has been recognized the major threat to health globally, which caused a total of 4.11 million deaths in 2017 [1]. Worldwide breast cancer is the most frequently diagnosed cancer and the first leading cause of cancer death among women. There were about 1.67 million new diagnosed breast cancer cases worldwide in 2012, which accounted for 25% of all new cancer cases in women [2]. With the development of medical technology, the survival rate in breast cancer had increased worldwide, but it varied in different countries [4]. The 5-years survival of breast cancer in China was 73.1%, which was lower than western countries (90.5%) [5].
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