Evaluation on Risk Factors and Preventative Measures for Breast

Cancer in China

Xiaolu Tang

University of Washington, Seattle, WA, 98105, U.S.A.

Keywords: Breast Cancer, Risk Factors, Screening, Prevention.

Abstract: Breast cancer is one of the leading causes of death among females worldwide. The number of people who

have been diagnosed with breast cancer is increasing rapidly in China. To better understand the current

situation of breast cancer and propose suggestions on reducing the risk of breast cancer, risk factors associated

with breast cancer and measures that can effectively prevent the onset of breast cancer are introduced and

discussed. The research is conducted in the form of a literature review by summarizing, comparing, and

analyzing previous research and proposing constructive suggestions on how breast cancer can be prevented.

The objective of this review is to analyze the risk factors and several preventative measures of breast cancer

and to provide suggestions on future works.

1 INTRODUCTION

Breast cancer is the most commonly diagnosed

cancer in women worldwide and ranks as second-

highest cancer related death among cancers in

women (Fahad Ullah 2019). Breast cancer is a type

of metastatic cancer involving a series of mutations

and can potentially affect other organs including the

brain and liver (Collaborative Group on Hormonal

Factors in Breast Cancer 2002). All women are at risk

of developing breast cancer and a general trend is

observed that the chances increase with age. The

incidence and prevalence rates of breast cancer are

relatively high in developed countries such as North

America and Australia, and relatively low in Eastern

Asia counties including China. However, the

incidence rate and mortality rate of breast cancer of

women in China are rising in recent years with an

increase of about 20–30 % over the past three

decades and an annual growth rate of 3-5% (Fan,

Strasser-Weippl, St Louis, Finkelstein & Goss, etc.

2014). Breast cancer in China is not fully understood

in terms of the causes of breast cancer and effective

prevention and treatment measures lagged far behind

developed countries. Although some risk factors,

which are essential to understand the epidemiology

of breast cancer, have been identified by previous

research, no comprehensive analysis has been

conducted to summarize risk factors associated with

breast cancer. China has made a great effort focusing

on the treatment of breast cancer, but preventative

measures and diagnosis are largely neglected, and

early diagnosis is essential to suppress the growth of

primary tumors and lower the mortality rate

significantly. This review mainly focuses on three

parts. An overview of the current situation of breast

cancer in Chinese women is presented by using

statistics obtained on incidence rate and mortality

rate in recent ten years. Several risk factors closely

related to breast cancer are analyzed. Moreover, the

efficacy of current preventative measures is

evaluated, and new preventative measures are

proposed.

2 CURRENT SITUATIONS OF

BREAST CANCER IN CHINA

The incidence rate of breast cancer in China was low

until the 1990s when the incidence rate rose more

than twice as fast as have global rates. The China

National Cancer Centre reported the incidence rate

by using the age-specific rate from 2004 to 2009. The

highest incidence rate occurred in age groups of 50–

54 for females, with an age-specific rate of 92–108

per 100,000 Chinese women. The slope of the

incidence-age group curve rose with increase in age,

became flat for the age group of 60–69 years, and

gradually decreased from the age of 70. The

Tang, X.

Evaluation on Risk Factors and Preventative Measures for Breast Cancer in China.

DOI: 10.5220/0011357100003444

In Proceedings of the 2nd Conference on Artiﬁcial Intelligence and Healthcare (CAIH 2021), pages 269-274

ISBN: 978-989-758-594-4

269

incidence rate generally increased from 2004 to 2009

for almost all age groups and the differences in

incidence rate became significant for people aged

above 50 years old. (Figure 1) The incidence rate also

varied significantly in different geographical

locations in China. Previous studies have

demonstrated that the average age-standardized rate

was 31.3 in urban areas compared to 12.1 per

100,000^2 in rural areas. The difference in incidence

rate can be attributed to factors such as variation in

socioeconomic status, accessibility to health

services, and difference in screening rate (Li, Mello-

Thoms & Brennan 2016).

Figure 1: Age-specific incidence rates of breast cancer in female from 2004 to 2009.

The trend in the mortality rate of breast cancer,

however, was inconsistent with the trend in incidence

rate in China from 2004 to 2009. The incidence rate

was lower for women aged above 60 years old

compared to women aged between 45 and 49, but the

mortality rate showed an increasing trend with age

and rose exponentially for women aged 85 and over.

(Fig. 2) Differences in mortality rates also existed

across geographical regions. Data have suggested

that the mortality rate tripled in urban areas

compared to rural areas with an increase of only 16%

from 2002 to 2008. The discrepancy can be explained

by the availably of sample sizes and limited access to

population-based statistics (Li, Mello-Thoms &

Brennan 2016).

Figure 2: Age-specific mortality rates of breast cancer in female from 2004 to 2009.

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Although some trends in the incidence rate and

mortality rate have been analyzed by using data

collected in recent one to two decades, only 13% of

the population has been included in the national

cancer registries in China. The dataset presented is

very limited and hard to reflect the comprehensive

situation of breast cancer through data interpretation

in China. Thus, expansion of cancer registration data

is essential, which would improve the accuracy in

estimating the number and burden of breast cancer

and better the current situation of breast cancer in

China.

3 RISK FACTORS ASSOCIATED

WITH BREAST CANCER

3.1 Genetic Factors

Breast cancer is largely caused by genetic factors and

many genes are associated with the chance of getting

breast cancer, including BRCA1/2, Epidermal

Growth Factor Receptor (EGFR), and HER2.

BRCA1/2 are tumor suppressor genes that suppress

cell growth when tumor cells are been detected. They

have the function of regulating the cell cycle

checkpoint and repairing DNA breaks to make sure

the normal function of cells. When deleterious

mutations happened in BRCA1/2 genes, the genes

lose functions and lead to the growth of tumor cells,

thus greatly increasing the risk of breast cancer.

However, developing cancer-related genes like

BRCA1/2 genes does not necessarily mean little

chance to survive through the disease. A meta-

analysis study conducted by Yaning Zhu et. al

examined the relationship between BRCA mutations

and patients’ survival rate, and the results are

summarized here to infer the association between

having BRCA 1/2 genes and breast cancer. The

survival rate of patients with breast cancer was

analyzed by using hazard ratios (HR) and breast

cancer-specific survival (BCSS). By examining the

results of 26 previous research reporting BRCA 1

mutation, BC patients with BRCA1mutation were

associated with worse OS compared to non-breast

cancer patients. The pooled HR was 1.69 (95% CI

1.35 to 2.12, p < 0.001; I2 = 59.1%) No association,

however, was found between BRCA1 mutation and

BCSS (HR = 1.14, 95% CI 0.81 to 1.61, p = 0.448;

I2 = 68.1%) The results were similar when analyzing

the BRCA2 mutations and patients had poor OS.

Also, no association has been found between BRCA2

mutation and BCSS (HR 1.16, 95% CI 0.82 to 1.66,

p = 0.401; I2 = 50.9%). The results might be

counterintuitive to many people but indicated

positive promises. As BRCA1/2 mutation did not

significantly influence the survival rate of patients,

actively and promptly seeking screenings and

treatments may increase the chance of survival for

breast cancer patients (Zhu, Zhang, Liu & Zhang

2016).

3.2 Breastfeeding and Parity

Breastfeeding is another risk factor associated with

breast cancer as breastfeeding and parity are related

to reproductive and hormonal receptors like estrogen

(ER). Parity is defined as the number of times that

women had given birth to a fetus. Previous studies

have confirmed that a 33% association was found

between parity and the increased risk of ER disease

(n = 1252; parous vs. nulliparous, RR = 1.33 [1.11–

1.59]). Women with higher parity who did not

breastfeed also had a higher risk of breast cancer

(e.g., ≥ 4 vs. 1 birth, RR = 1.68 [1.15–2.44]) but

not among women reporting ever breastfeeding (RR

= 1.33 [0.91–1.95]). Consequently, breastfeeding and

number of parity had been confirmed to significantly

influence the chance of whether women would get

breast cancer (Fortner, Sisti, Chai, Collins, Rosner &

Eliassen 2019). The one-child policy was a policy

unique in China implemented at the beginning of the

1980s, and it largely affected the breastfeeding

pattern for pregnant Chinese women. The total

fertility rate had decreased significantly from about

6.0 in 1950 to 1.6 in 2020 (Collaborative Group on

Hormonal Factors in Breast Cancer 2002). Since

women were only legally allowed to have one child,

the number of parity and the time for breastfeeding

declined dramatically. Thus, the risk of breast cancer

would likely increase during those 30 years.

3.3 Dietary Pattern

As economics rapidly developed in China, the

economic status of people have improved and they

could choose more options in terms of eating and

living. The diet of many Chinese people has changed

from a healthy traditional diet based on vegetables,

soybeans, and rice to a modern western diet that

contains too much fat. The Women’s Health

Initiative Randomized Controlled confirmed the

association between low-fat dietary patterns and risk

of breast cancer by examining 48,835

postmenopausal women from 1993 to 1998 at 40 US

clinical centers. The results demonstrated that during

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the 8.5 years intervention, the number of deaths had

reduced for breast cancer patients receiving the

dietary intervention, compared to those in the control

group (27 deaths [0.016% per year] v 61 deaths

[0.024% per year]; HR, 0.67; 95% CI, 0.43 to 1.06;

P = .08). A similar trend was found when dietary

intervention lasted for 16.1 years with 3,030 incident

breast cancers. Few deaths were observed in patients

in dietary group in contrast to patients in control

group (111 deaths [0.035% per year] v 185 deaths

[0.039% per year]; HR, 0.91; 95% CI, 0.72 to 1.15)

(Collaborative Group on Hormonal Factors in Breast

Cancer, 2002). When changing to a low-fat dietary

pattern, the risk of breast cancer and death was

significantly decreased. Other than reducing the

frequency of consuming food containing a lot of fat,

eating fiber may help prevent the onset of breast

cancer to some extent because fiber can reduce

cholesterol levels in the blood and even destroy

carcinogens.

4 PREVENTATIVE MEASURES

OF BREAST CANCER

4.1 Screening

Early detection and screening are important for

breast cancer prevention because many primary

tumors can be removed by surgery. There are mainly

two types of screening that are currently being used

to screen for breast cancer. Mammography is an

effective screening method that utilizes low-energy

X-rays to obtain high-resolution images of the breast,

but it can lead to problems like overdiagnosis. MRI

is another screening tool that has been widely applied

for breast cancer. The sensitivity of MRI is higher

than mammography, but the specificity of MRI is

much poorer than that of mammography with lower

detection rates (Fan, Strasser-Weippl, St Louis,

Finkelstein & Goss, etc. 2014).

Despite the development of screening technology

that makes early detection of breast cancer possible,

the screening rate is never optimistic in China.

Statistics have shown that the screening rate for

breast cancer was 25.7% for women aged between 35

and 64 years in 2015. Even though the screening rate

increased by 3% from 2013 to 2015, the number was

low compared to developed countries with a

screening rate of above 50%. Moreover, women in

rural areas and with low education levels had

significantly lower screening rates. Some screening

programs had been implemented since 2009 in China

which specifically provide easy access to screening

for rural female residents aged 35-59 years old,

however, the screening rate only increased partially

and there is no nationwide screening program for

breast cancer in China at present (China CDC

Weekly 2021). Therefore, continued efforts should

be made by governments and organizations to give

initiatives and financial support to implement more

screening programs for breast cancer. Also, screening

for breast cancer should be included in the regular

health check-up for women especially those above 35

years old and screening expenditures can be included

in health insurance to alleviate the burden of

financial difficulties especially in rural areas.

4.2 Chemoprevention

Chemotherapy is a primary method used for the

prevention and treatment of breast cancer worldwide.

It is an aggressive form of chemical drug therapy that

destroys the growing cells in the body. The estrogen

receptor is often a major target for chemotherapy

because over of 70% patients have ER-positive

breast cancer. Currently, two major classes of anti-

estrogen drugs are selective estrogen receptor

modulators (SERMs) and aromatase inhibitors (AIs)

(Zhu, Zhang, Liu & Zhang 2016). Although SERMs

and AIs have certain efficacy in treating breast

cancer, their side effects cannot be ignored including

stroke, osteoporosis, and joint pain. Thus,

researching on drugs that can be both effectively

target the disease and with few side effects is of high

priority. Neoadjuvant chemotherapy is a relatively

advanced method in early-stage prevention and

treatment for breast cancer. Neoadjuvant

chemotherapy works by targeting the primary tumors

fixed to the chest wall or skin, decreasing the size of

tumor cells before conducting surgery. Studies

conducted by MD Anderson have shown that the

survival rate of breast cancer patients increased

significantly if neoadjuvant chemotherapy was

implemented, and the size of tumors was reduced by

50% in at least 67% of patients in the study (Redden

& Fuhrman 2013).

In China, neoadjuvant chemotherapy is gradually

being used in the prevention and treatment of breast

cancer and in the stage of continuous development.

With the emergence of various clinical trials and new

treatment concepts, the treatment model has been

transformed from single chemotherapy to current

neoadjuvant chemotherapy based on different breast

cancer molecular subtypes. As new evidence-based

medicine data continue to be enriched, the

differences between various therapeutic concepts

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and clinical practice become more obvious. Thus,

more emphasis should be placed on selecting and

applying neoadjuvant chemotherapy in clinical

practice, optimizing the treatment strategy for

patients, and improving treatment outcomes.

4.3 Changes in Diet Pattern

Another effective preventative measure is to promote

a healthy diet and lifestyle, which could be a risk

factor leading to breast cancer. Evidence has

demonstrated that a diet rich in saturated fat would

increase the risk of breast cancer, so promoting a diet

that includes rice, fresh vegetables, soy, pork would

reduce the risk of breast cancer. Dietary fiber is also

beneficial in preventing breast cancer as it promotes

the growth of probiotics and inhibits the growth of

pathogenic bacteria, which significantly reduces the

risk of breast cancer, especially for postmenopausal

women (Zhao, Zhang, Deng, etc. 2016). China has

implemented some policies in an effort to increase

the awareness of people in pursuing a healthy life.

One of them is The Healthy China Initiative 2019-

2030, which aims to improve national health policies

and provide comprehensive health services for

people. It addresses the urgent need to increase the

awareness of having a healthy diet among people and

to strengthen guidance on nutrition and health works

in schools and institutions. The policies are essential

to solve current health problems such as malnutrition

and excessive intake of high-calorie food, thereby

preventing breast cancer and other cancer diseases.

5 CONCLUSIONS

Breast cancer is becoming more common in China

with a rising incidence rate and mortality rate.

Identifying risk factors and implementing

preventative measures are important to reduce the

risk of breast cancer. The increase in the number of

Chinese women getting breast cancer is due to the

ignorant of risk factors that potentially lead to breast

cancer, and low awareness and financial difficulties

in conducting preventative measures timely.

Concrete and comprehensive programs and policies,

such as National Screening Program and Health

China Initiative, are necessary to improve

preventative measures and promote awareness of risk

factors associated with breast cancer.

Chinese government and institutions should

make continuous efforts in increasing the awareness

and knowledge of the public, providing more

convenient health services for early diagnosis

especially in rural areas, and improving biomedical

techniques to increase the accuracy of the breast

cancer diagnosis. The paper is subjected to some

limitations. The data used for the incidence rate and

mortality rate of breast cancer might not reflect the

actual situations of breast cancer in China as many

people are not included in the database. Moreover,

only risk factors that have been shown to have a

strong association with the risk of having breast

cancer were included and risk factors such as stress

and mood, which are hard to be analyzed

quantitatively, did not add into consideration. For

future works, more research and analysis can be

conducted on testing whether improving the

implementation of preventative measures of breast

cancer mentioned would decrease the risk of breast

cancer.

ACKNOWLEDGMENT

I would like to thank Prof. Trochim from Cornell

University and teaching assistant Yuanyuan Dong for

teaching me knowledge in public health and cancer-

related areas and provide me guidance with this

research paper.

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