This was the first geographically representative epidemiologic study of breast cancer in China and included more than 4,000 patients over its course. This study, via its inclusion of a large number of sites across all seven traditional regions of China, facilitated a thorough assessment of breast cancer patient characteristics, treatment allocation, and allowing a unique analysis of possible regional variations in these aspects of breast epidemiology and management across the entire country. It also helps to determine levels of unmet medical need and identify regions of high risk for breast cancer within China.
All patients included in our study were ethnically Chinese. Their clinical characteristics were significantly different from those of the women in western countries. The mean age at diagnosis was 48.7 years, and this was similar to the findings from other regional studies within China [9–14]. It was also in agreement with reports from other Asian countries such as Singapore, India and also similar to Saudi Arabia, all of which were around the mid-40s. This was about a decade earlier than what is reported for Western Caucasian women [15–19]. The reasons for the distinctions remain obscure, but four hypotheses may explain. First, older Asians including Chinese women had been less exposed to estrogen related risk factors thus have been less susceptible to breast cancer than their younger counterparts. Second, younger women were more genetically predisposed to breast cancer. Third, younger women were more aware of breast cancer. They have broader access to medical care as there is no nationwide organized screening program in China as well as in the majority of the modernizing Asian countries. Fourth, mammography has been used among older women in the population based mammography screening in Western countries. This may partly account for why breast cancer clusters peak around 60-69 years in Western countries.
In this study, 60.6% of the patients had early stage breast cancer and 21.4%% had late stage disease. The incidence of early stage disease on presentation was lower than the data from China Tianjin (72.3%) , Taiwan (78.3%)  and Singapore (79%) , and much lower than the western countries such as the United States (85%) . A study from Hong Kong which focused on a selected group of affluent Chinese patients reported an 88.9% of early stage cases . While in the African countries, large proportions of patients presenting at late stage were reported, early stage cases accounted for only 9.27% to 42.7% [22–25]. The vast difference between regions and countries may due to the absence of a nationwide breast cancer screening program in developing countries including China, whereas such programs are fully or partly implemented in the majority of developed countries . The findings of our study also suggest that women who were mental workers and had at least a university education were more likely to present breast cancer at early stage. This is in consistent with reports from a review article that socioeconomic disparities including low family income, poor educational attainment and impaired access to healthcare etc were related to the more advanced disease at diagnosis and poorer prognosis .
ER positive breast cancers are acknowledged to be related to a better prognosis than those that are ER negative  as they respond better to hormone therapy . HER-2 positive breast cancers are more aggressive and require more expensive therapy . In our study, 57.4% (2,028/3,534) were ER positive and 25.8% (736/2,849) were HER-2 positive. The ER status of Chinese breast cancer was documented previously and the positivity varied from 45.3% to 67% [31–35]. When compared with data from developed countries, the positivity from our study is significantly lower [36, 37]. The prevalence of HER-2 has been documented to be 27.9% in a Chinese study  and 15% in one study from the United States . It suggests that breast cancer in Chinese women may be more aggressive than those in the developed countries, but those differences may also be explained by the un-uniformed tests used, different cut-off value referred, and bias from the age distribution in various studies. Although our study sample is representative, the tests were done retrospectively and different methods and protocols were conducted. Further study using a representative sample and standard protocol to understand the status of ER/PR/HER-2 status in Chinese breast cancer is necessary and would make it more comparable.
Surgery was the most common treatment in Chinese female breast cancer patients followed by chemotherapy. Among all surgery procedures, radical mastectomy was widely perceived as the only curative treatment, which is consistent with a study from Hong Kong . Options for radiotherapy and endocrine therapy were much less, which indicates that adjuvant therapy, especially radiotherapy and endocrine therapy are of great unmet needs. Further analysis and studies were necessary to understand the patterns of treatment based on detailed information of treatment indications such as tumor size, lymph node involvement, final margins, and ER status.
These findings will need to be considered in light of the study's strengths and weaknesses. The primary strengths of this study are (1) the large number of patients included and (2) the geographic representativeness of the included sites. The main potential study limitations are (1) selection bias may exist in the catchment of breast cancer patients in the selected hospitals as no less elite hospitals as comparison were selected from the same regions. (2) There is no comparison group to compare the risk factors of developing breast cancer and (3) data quality is dependent on the thoroughness of the clinician's documentation of medical history, treatment, and outcomes.