The burden of breast cancer from China to Italy.

Abstract

Breast cancer is the second most common cancer in the world and the most frequent cancer among women, with an estimated 1.67 million new cancer cases diagnosed in 2012 (25% of all cancers) (1). In Europe the estimated age-adjusted annual incidence of breast cancer in 2012 was 94.2/100 thousand and the mortality 23.1/100 thousand (2). In USA, according to the SEER database [2006-2010], the age-adjusted annual incidence of breast cancer was 123.8/100 thousand and the mortality 22.6/100 thousand (3). The median age at breast cancer diagnosis is 61 years: about 10% of breast cancers occur among women aged younger than 50 years, while 65% occur among women aged 65 years or older (3). Overall, 60% of breast cancers are diagnosed at a localized stage, 32% at a regional stage and 5% at an advanced stage. The 5-year relative survival rate for women diagnosed with localized breast cancer is 98.6%; survival declines to 84.4% for regional stage and 24.3% for distant stage (3). In western countries, due to both early detection through screening programs and the improvement in the available treatment strategies, the percentage of women surviving at least 5 years after diagnosis and treatment has shifted from 74.8% in the early 1970s to 90.3% in the late 1990s (3). In Italy, it has been estimated that approximately 48,000 new cases of breast cancer has been diagnosed in 2013 (4). Excluding skin cancers, breast cancer is the most common cancer diagnosed in women: a total of 41% are diagnosed in the age group 0-49 years, 36% in patients aged 50-69 years and 21% in women older than 70 years (2,4,5). Breast cancer incidence and prevalence present a marked north-to-south gradient: the incidence rates are respectively 124.9, 100.3 and 95.6 per 100 thousand in the northern, central and southern areas (5). Regarding breast cancer prevalence, the proportion of prevalent cases in the northern area is remarkably higher (2,055-2,331 per 100 thousand) than in the central area (1,795 per 100 thousand) and about twice than in the southern area (1,151 per 100 thousand). In Italy, breast cancer mortality increased until the late 1980s reaching its maximum value at approximately 27 per 100 thousand, and started to decline thereafter (approximately –1.6%/year) (2). The mortality rate started to decline from the late 1980s in the northern central regions and from the mid-1990s in the southern regions. The 5-year relative survival increased from 78% in 1990-1992 to 87% in 2005-2007 (6,7); age standardized mortality rates are lower in the central area (20.6 per 100 thousand) than in the northern (24.7 per 100 thousand) and southern (25.2 per 100 thousand) areas (4). Breast cancer is a major burden also for Chinese women: Zeng and colleagues recently described the epidemiology of breast cancer in China in 2010, reporting breast cancer statistics by age and geographical area (8). Authors estimated the status of female breast cancer based on existing population-based cancer registries’ data available in 2010; these registries covered approximately 12.96% of the overall female population in China. The estimated number of female breast cancer cases was about 208 thousand; the overall crude incidence rate was 32.43 per 100 thousand, accounting for 16.2% of all cancer cases in Chinese women (first cause of cancer diagnosis). The rates standardized by World population and by China population were 24.20 per 100 thousand and 25.89 per 100 thousand respectively. The estimated number of female breast cancer death was about 55.5 thousand with an overall crude mortality rate of 8.65 per 100 thousand, accounting for 7.90% of all cancer deaths (fifth cause of cancer deaths in Chinese women). After age standardization by China population and World population, the standardized rates were 6.56 per 100 thousand and