In China, the health burden of cancer is growing every year, with more than 1.6 million diagnoses and 1.2 million deaths due to cancer each year. As in most other countries, breast cancer is the most common cancer among Chinese women; it accounts for 12.2 percent of new cases and 9.6 percent of deaths worldwide each year. The progressive increase in China’s global “contribution” is largely attributed to the country’s increasing socioeconomic status and specific fertility patterns.
In this review, we will outline current measures to control breast cancer in China, highlighting disparities in epidemiology and socioeconomics, and identifying disparities in treatment access for different populations.
Incidence
The Global Oncology Epidemiology Statistics (GLOBOCAN) identifies breast cancer as the most common cancer among Chinese women, with an age-specified rate (ASR) of 21.6 cases per 100,000 people. According to the Chinese National Tumor Registry, breast cancer is the most common cancer among urban women and the fourth most common cancer among rural women. The ASR in urban areas (34.3 cases per 100,000 women) was twice as high as in rural areas (17.0 cases per 100,000 women).
The incidence rate is highest in socioeconomically developed coastal cities, with an ASR of 46.6 cases/100,000 women for breast cancer in Guangzhou, a rate close to that of Japan (ASR: 42.7 cases/100,000 women). In contrast, in the less developed regions of central and western China, the ASR can be lower than 7.94 cases/100,000 women.
In China, the average age at diagnosis of breast cancer is 45-55 years, which is younger than Western women. Data from Shanghai and Beijing show two peak incidences of breast cancer, the first occurring between 45-55 years of age and the other between 70-74 years of age, with a progressive increase in the median age of diagnosis. 16.6% of breast cancer patients in China were older than 65 years of age in 2008 (compared to 42.6% in the United States), and this figure will increase to 27.0% by 2030. This figure will increase to 27.0% by 2030.
Breast Cancer Age Score
Note: Data compare the age distribution of breast cancer in China and the United States in 2008 and estimate the age distribution of breast cancer in China in 2020 and 2030; data source WHO China Country Profile The specific peak incidence of 45-55 years is probably due to the presence of a birth cohort effect. Changes in menstrual and reproductive patterns, as well as other lifestyle and environmental factors, are prevalent in most birth cohorts. Similar birth cohort effects have been reported in Taiwan and Hong Kong, and this effect accentuates the role of risk factors in women at younger ages.
Mortality
In 2008, GLOBOCAN reported that breast cancer was the sixth leading cause of cancer death in Chinese women after lung, stomach, liver, esophageal, and colorectal cancers, with an ASR of 5.7 cases per 100,000 women. One of the reasons for the gradual increase in breast cancer mortality in urban and rural areas over the past three decades is the gradual increase in cancer registration data. The ASR in urban areas is 46.9% higher at 7.2 cases per 100,000 women than in rural areas (ASR: 4.9 cases per 100,000 women).
We hypothesize that the survival rate of breast cancer patients is lower in the less economically developed inland rural areas, while in the better socioeconomic areas the survival rate will be close to that of Shanghai. In order to eliminate the disparity, further research and clarification of the causes are needed.
Risk factors for breast cancer in Chinese women
The risk factors for breast cancer in Chinese women are only partially consistent with those in high-income countries. Some of them are the same as in the West: reproductive and hormonal factors such as long menstrual life (early menarche or delayed menopause), never having given birth, delayed age at first birth, and limited breastfeeding. These factors slowly increase the risk of breast cancer in the Chinese population. Declining fertility (in part due to the one-child policy) can also indirectly affect breast cancer risk (e.g., by reducing the duration of breastfeeding).
In China, multiple childbearing was associated with a low risk of breast cancer in postmenopausal women (ratio OR, 0.69; 95% CI, 0.52-0.91). The total fertility rate (average number of children per woman over her lifetime) in China decreased from 6.0 in 1950-1955 to 1.6 in 2010, with the lowest total fertility rate in affluent coastal cities.
Screening and early diagnosis of breast cancer
Whether mammography before age 50 is beneficial is controversial; however, 57% of patients in China are in this age group. This result may explain why cost effectiveness studies of mammography are not as convincing in Western women as they are in Chinese women.
A study done in Beijing found that only 5.2% of new breast cancer cases were detected by regular mammography screening, while 82.1% of women had already had significant symptoms by the time they were detected. In China, there is a need to further increase public awareness, to continue research on the role of mammography and clinical breast examinations in the early detection of breast cancer, and to provide more available medical services so that Chinese women are willing to be screened.
Clinical Diagnosis
1. Age at diagnosis
The median age of diagnosis of breast cancer for Chinese women is 48-50 years compared to 64 years in the United States. 57.4% of Chinese women patients are diagnosed with breast cancer before the age of 50, and 62.9% of women are not yet menopausal at the time of breast cancer diagnosis. However, the median age of diagnosis continues to increase.
2. Staging at diagnosis and delaying early detection
The frequency of advanced breast cancer is a major cause of the survival disparity between African American women and white women. A multicenter nationwide study in China showed that 15.7% of patients were in stage I, 44.9% in stage II, 18.7% in stage III, and 2.4% in stage IV when diagnosed with breast cancer. Compared to women of lower socioeconomic status who presented more stage III and IV, upper class women presented more stage I and II.
3. Diagnosis and pathology report
Although image-guided aspiration biopsy is the gold standard for the diagnosis of primary breast cancer, data from Beijing showed that 34.1% of patients were diagnosed with breast cancer by hollow needle aspiration biopsy, 19.0% by fine needle aspiration cytology, and 46.9% by intraoperative tissue freeze biopsy. Although this data is not representative of China as a whole, the data from such a developed city has demonstrated the deficiencies in diagnosing primary breast cancer.
In general, the molecular and genetic characteristics of breast tumors in Asian countries are similar to those of Caucasians. The prevalence of hormone receptor positivity is relatively low in Chinese female patients, about 50-60%, compared to over 70% in Caucasians, perhaps due to the younger age of the affected population in China. This view is supported by the fact that the prevalence of estrogen receptor-positive disease in China is gradually increasing, similar to the increasing age of diagnosis of breast cancer.
In Beijing, even 8.9% of patients could not be tested for HER2 and close to 10% of patients had ambiguous immunohistochemistry results and were not tested for HER2 by further in situ fluorescence hybridization. Control Center see http://www.mpathology.cn) to help improve the accuracy of HER2 testing. Even so, work needs to be done on accurate measurement.
Breast Cancer Treatment
1. Surgery
The timeliness and effectiveness of the best treatment for breast cancer affects clinical outcomes, but these two points vary greatly in China. The surgical methods used to treat breast cancer vary greatly from region to region and from hospital to hospital. Since the 1990s, breast-conserving surgery (whenever possible) has been the surgical treatment recommended by reference guidelines.
To improve the rate of sentinel lymph node biopsy, an ongoing study conducted by the Chinese Breast Cancer Clinical Collaborative Group (CBCSG001) included preoperative lymph node scintigraphy and case report safety and efficacy of sentinel lymph node biopsy as secondary study endpoints.
2. Radiotherapy
Results from a retrospective epidemiological study in China showed that only 27% of breast cancer patients nationwide received radiation therapy as part of their primary treatment, a lower rate than in other countries (e.g., 40% in Korea, 58-68% in the Netherlands, and 76% in Brazil)
In China, drug reimbursement policies have a significant impact on optimal systemic therapy choices. Many drugs are not covered by health insurance, which in effect increases the out-of-pocket costs for patients. Lack of access to new drugs also limits the range of systemic therapy options for metastatic disease.
3. Palliative care for breast cancer patients
China lacks support for general health treatment and end-of-life care. According to a study by The Economist Intelligence Unit, China’s end-of-life and palliative care programs are poorly developed, ranking 37th out of 40 countries.