Contrasting Epidemiology and Clinicopathology of Female Breast Cancer in Asians vs the US Population

Abstract

Background The incidence of breast cancer among younger East Asian women has been increasing rapidly over recent decades. This international collaborative study systemically compared the differences in age-specific incidences and pathological characteristics of breast cancer in East Asian women and women of predominantly European ancestry. Methods We excerpted analytic data from six national cancer registries (979 675 cases) and eight hospitals (18 008 cases) in East Asian countries and/or regions and, for comparisons, from the US Surveillance, Epidemiology, and End Results program database. Linear regression analyses of age-specific incidences of female breast cancer and logistic regression analyses of age-specific pathological characteristics of breast cancer were performed. All statistical tests were two-sided. Results Unlike female colorectal cancer, the age-specific incidences of breast cancer among East Asian women aged 59 years and younger increased disproportionally over recent decades relative to rates in US contemporaries. For years 2010–2014, the estimated age-specific probability of estrogen receptor positivity increased with age in American patients, whereas that of triple-negative breast cancer (TNBC) declined with age. No similar trends were evident in East Asian patients; their probability of estrogen receptor positivity at age 40–49 years was statistically significantly higher (odd ratio [OR] = 1.50, 95% confidence interval [CI] = 1.36 to 1.67, P < .001) and of TNBC was statistically significantly lower (OR = 0.79, 95% CI = 0.71 to 0.88, P < .001), whereas the probability of ER positivity at age 50–59 years was statistically significantly lower (OR = 0.88, 95% CI = 0.828 to 0.95, P < .001). Subgroup analyses of US Surveillance, Epidemiology, and End Results data showed similarly distinct patterns between East Asian American and white American patients. Conclusions Contrasting age-specific incidences and pathological characteristics of breast cancer between East Asian and American women, as well as between East Asian Americans and white Americans, suggests racial differences in the biology.

The prognosis of early-stage breast cancer in extremely young female patients

“…[ 20 , 21 ] In East Asian women, the incidence of breast cancer in younger patients is increased disproportionally compared with rates in American women. [ 12 ] There are few data providing survival outcomes in breast cancer patients younger than 30 years old. [ 22 , 23 ] Most studies have focused on patients younger than 40 years of age.…”

“…[ 11 ] Furthermore, a recently published study shows that the biology of breast cancer exhibits racial differences, which contributes to the increasing breast cancer incidence of the young population in East Asia. [ 12 ] Breast cancer at a young age has the following characteristics: history of breast cancer in close relatives, particular lifestyle, a lower proportion of the luminal subtype, a more aggressive nature, higher rates of locoregional recurrence, and a greater risk of breast cancer-related death. [ 13 – 16 ]…”

A Phase Ib Study of Alpelisib or Buparlisib Combined with Tamoxifen Plus Goserelin in Premenopausal Women with HR-Positive HER2-Negative Advanced Breast Cancer

“…In the United States, breast cancer predominantly affects women ages 60 years and above, whereas in East Asia, incidence peaks in women ages 40-75 years (2). Approximately 42% of women in the Asia-Pacific region and 47% in Southeastern Asia were younger than 50 years at the time of diagnosis, in contrast to 20% of women in Western countries (3,4).…”

“…The most common molecular subtype of breast cancer is luminal disease, characterized as hormone receptor-positive (HR þ ) and HER2negative (HER2 À ), occurring in approximately 70% of cases (5,6). In East Asia, the prevalence rate of luminal disease is even higher in premenopausal patients with breast cancer than in postmenopausal patients (2). Treatment options for premenopausal patients with HR þ , HER2 À , advanced breast cancer (ABC; includes locally advanced and metastatic disease) remain limited, and are mostly inferred from trials that enrolled postmenopausal women (7)(8)(9)(10)(11)(12).…”

Implications of Tamoxifen Resistance in Palbociclib Efficacy for Patients with Hormone Receptor-Positive, HER2-Negative Metastatic Breast Cancer: Subgroup Analyses of KCSG-BR15-10 (YoungPEARL)

“…they are more commonly found in Eastern countries compared to Western countries, owing to different ethnic background along with environmental and social factors [12][13][14][15][16]. In many Asian countries, the peak incidence of breast cancer occurs at the age range of 40-50 years, leading to about half of the patients being premenopausal.…”