Incidence and mortality rates for breast cancer: Differences according to ethnicity.

Despite huge improvements in breast cancer treatment and overall survival rates, there still remains some interesting differences according to racial background.

In general, it is safe to say that the incidence of breast cancer has increased over the years, whilst mortality rates have decreased. This is probably due to better screening programs and improved targeted treatments.

According to the American Cancer Society, in 2015 a whopping 231,840 women will be diagnosed with invasive breast cancer in the United States. In addition, it is estimated that there will be around 60,290 new cases of in-situ cancers.

A number of studies have examined breast cancer incidence rates and have shown differences based on ethnic and racial groups.

Some studies speculate that certain racial groups are genetically more or less predisposed to breast cancer development. However, other medical experts point to socio-economic factors to explain the difference in breast cancer incidence and mortality rates.

I would like to let you know that this post has been recently up-dated with all the latest information and statistics. However, there is a wealth of general information on our new breast cancer site. Other posts that may be of interest include general survival rates for breast cancer and survival rates by stage.

Incidence of breast Cancer According to Race and Ethnicity

The concept of variation in incidence rates and prognosis, according to ethnicity, in breast cancer is not a new one. Data collected from the United States suggests a difference in both incidence rates and outcomes that we will have a look at in the post.

The breast cancer incidence rates describe how many women out of 100,000 get breast cancer each year.

According to statistics from the CDC National Program of Cancer Registries and National Cancer Institute’s Surveillance, Epidemiology and End Results program show that in 2013:-

White women had the highest rate of breast cancer
Black women had the second highest rate
Hispanic women had the third highest rate
Asian/Pacific Islanders had the second lowest breast cancer incidence rate. (API on our graph)
American Indian/Alaska Native women had the lowest breast cancer incidence rate (AI/NA on our graph)

… and just to prove it, we have made a graph. Here it comes …

As we can see from our latest graph above, the breast cancer incidence rates vary amongst different ethnic groups.

Furthermore, the graph above uses the latest statistics available from 2013.

Just for comparison, I have left the old chart showing breast cancer incidence rates according to age and race. These figures are taken from data between 1998 and 2002.

Wow! That is a LONG time ago now Doc!

Okay, Moose. I know, I know.
I’ve been doing this for a long time … but that doesn’t mean I’m old!

Breast Cancer incidence rates by race and age group.

(USA. 1998-2002)

According to the American Cancer Society, between the years of 2008 and 2012, breast cancer incidence rates increased amongst black women and Asian/Pacific Islanders. Conversely, incidence rates remained stable amongst white women, Hispanic and American Indian/Alaska Natives, for the same years.

White women have traditionally had the highest incident rate for breast cancer. However, in 2012, the incidence rates for white women and black women converged.

In the 2013 statistics, the incidence rate remains quite close. White women have an incidence rate of 124.4 per 100,000 and black women, just a little less at 122.9 per 100,000.

Although incidence rates are similar now amongst black and white women, there remain differences based on age and stage at diagnosis.

What can women do to lower the risk of breast cancer?

Well, maintain a healthy weight and
get some physical exercise. Don’t smoke or drink alcohol in excess … and get regular mammograms.

A little more on Incidence Rates by Race

In comparison to white women, breast cancer incidence rate is higher amongst black women who are younger than 60 years and lower for those aged 60 or more.

In addition, between 1999 and 2013 in women (aged 60 to 79 years) rates of breast cancer significantly decreased for white women and significantly increased for black women in comparison. Differences in age at diagnosis also plays a role in other racial groups.

Furthermore, black women had a 54% rate of diagnosis at a localized stage, compared to 64% in white women.

In addition, black women are more likely to be diagnosed with specific subtypes, such as triple negative breast cancer, which is more difficult to treat.

There are also geographical factors that play a role in breast cancer incidence rates. For example, for black women, there are higher breast cancer rates in the south of the USA and these do vary from state to state.

The same applies to Native American women. Although this ethnic group has the lowest incidence rate of breast cancer, those that live in Alaska have similar incidence rates to white women.

So, there are quite a lot of factors related to race and breast cancer.

Oh Yes, so many. There are often issues with racial classifications too.

Breast Cancer Mortality by Race

It is well known that mortality rates for breast cancer in different ethnic groups do not match the incidence rates.

The good news is that between the years of 1989 to 2012 the overall breast cancer death rate in the United States decreased by 36%. This decrease in deaths was apparent for all ethnic groups except American Indians/Alaska Natives.

However, between the years of 1999 to 2013 the mortality rate for breast cancer continues to vary according to ethnicity. Indeed, in 2013, the death rate for black women was 42% higher than that of white women, even though incidence rates are fairly similar.

So we can see from the above graph, that mortality rates do not match incidence rates for breast cancer when racial groups are compared.

The highest mortality rates are in the black ethnic group, followed by whites and then American Indian/Alaska Native (API). The lowest mortality rate is for Asian/Pacific Islanders (API).

The Hispanic group have the third highest incidence rate, but the second lowest death rates according to latest statistics.

So, let’s take a look at some earlier data and compare. Below are breast cancer mortality rates by race between 1998 and 2002.

Breast Cancer Mortality by race and age group.

(USA. 1998-2002)

Discussion on Breast Cancer Mortality by Race

We can see from the above chart that the general trends in mortality rates for breast cancer, according to ethnicity, have not significantly changed over the years.

Black women still had the highest death rates, followed by white women. However, the death rates widen between black and white women according to age. Younger black women between the ages of 45 and 60 do not fare as well.

Caucasians have a mortality rate almost as high as African Americans. Both groups appear to be considerably more prone to death from breast cancer than native Americans, Hispanics, and Asians.

In fact, the breast cancer mortality rate for black and Caucasian women was basically twice that of the other racial groups.

What is most striking about these statistics is that the mortality rate for black women is slightly higher than that for Caucasian women. However, the incidence rate for black women was considerably lower at the time.

For Hispanic, American Indian/Alaskan Native (AI/AN) and Asian and Pacific Islanders (API) the mortality rates were all fairly similar up to the age of 64.

The Hispanic ethnic group had the third highest death rate followed by the AI/AN and the lowest mortality rate unchanged for the API. When compared to our latest graph, Hispanic women now have lower mortality rates than AI/AN.

Why are there differences for breast cancer mortality rates according to race?

That is a very complex question,
Moose. But, let’s take a look …

What are the reasons for the Disparities in Breast Cancer Mortality by Race

The differences in breast cancer survival rates according to ethnicity remain a huge concern to medical experts. African American women are experiencing a rise in incidence rates and a widening difference in survival rates compared to white Caucasian women.

The contributing factors for some of the interesting statistics that we have seen, according to one 2011 medical research study include:-

(i) Advanced stage at diagnosis due to low screening rates
(ii) Biological Factors including Tumor type
(iii) Comorbidity
(iv) Socioeconomic Status
(v) Obesity and Physical Exercise

(i) Advanced stage at diagnosis according to Ethnicity

The stage of breast cancer at diagnosis is so important to prognosis, thus the earlier stage at diagnosis, the better the outcome.

A recent 2015 study examined 102,064 women over the age of 20 from the SEER data registry, all who had invasive breast cancer between 2010 and 2011.

The results showed that African American and Hispanic women were 30% to 60% more likely to be diagnosed with stage II to IV breast cancer than Caucasian white women.

Furthermore, African American women were 40% to 70% more likely to be diagnosed with Stage IV breast cancer. American Indian/Alaska Native were 3.9 times more likely to have Stage IV triple-negative breast cancer.

When you look at the 2012 survival statistics above the impact of the medical study regarding stage and ethnicity is clear.

In addition, African American and Hispanic breast cancer patients were at higher risk of not receiving breast cancer treatment according to guidelines across all sub-types.

Stage at diagnosis of breast cancer is one of the most important prognostic factors.

This is why it is SO important for women to attend regular screening.

(ii)Biological Factors including Tumor Type

African American women tend to be diagnosed with breast cancer at a younger age than white women. Age at diagnosis is one of the factors associated with prognosis.

Furthermore, many studies have recognised biological abnormalities that promote tumor growth in African American women. These abnormalities include higher incidence of alterations in a variety of cell cycle regulatory proteins.

Triple-negative breast cancer, and ER-negative breast cancer are both found more commonly in African American women and Hispanics. These tumors are aggressive, and more likely to present with axillary node positivity.

In addition, triple-negative breast cancer does not respond as well to treatment and is associated with a poorer prognosis.

There has been some evidence to suggest differing underlying genetic factors can increase the breast cancer risk. One medical study found a genetic variant in African-American women that increases the risk of breast cancer by 23%.

Comor…What?

Comorbidity relates to any other underlying medical condition that exists at the time of diagnosis.

(iii) Comorbidity

A number of studies have shown poorer survival rates amongst cancer patients with other underlying medical diseases (comorbidity)

One large medical study followed breast cancer patients with a history of Myocardial Infarction (heart attack) or diabetes. It was found that patients with diabetes or MI had a 1.5 and 1.9 greater risk of dying from breast cancer than other patients.

It is known that there are high rates of hypertension, obesity and diabetes amongst African American, Hispanic and Asian/Pacific Island women.

These underlying conditions are associated with worse prognosis and outcomes that may be explained by less tolerance to cancer treatments combined with less aggressive treatments.

Frequent existing conditions at breast cancer diagnosis include cerebrovascular disease, diabetes and chronic pulmonary disease. Also, dementia seemed to worsen prognosis for breast cancer patients.

(iv) Socioeconomic Factors

Unfortunately, for women with lower education and income breast cancer outcomes tend to be worse than for their wealthier counterparts.

According to a 2015 CDC report on health disparities, there remain concerning ethnic differences regarding health insurance coverage, education and poverty status.

However, the whole role of socioeconomic factors in relation to breast cancer survival statistics is quite complex.

Studies have clearly demonstrated that socioeconomic factors DO strongly influence the stage of breast cancer at diagnosis. However, the hypothesis that African Americans have less access to medical centers and breast cancer screening does not explain all.

When access to medical care and screening is ensured and equal across ethnic groups, there remain racial disparities in breast cancer diagnosis and survival.

Interestingly, studies have shown that Caucasian white women with breast cancer and low socioeconomic status have similar poorer outcomes to other ethnic groups.

It is interesting because women of high socioeconomic status have also been shown to have a higher risk of breast cancer. This is thought to be due to alcohol consumption, fewer children, older age at the birth of first child and use of contraception pills and HRT.

Obesity and Physical Activity

In light of higher obesity rates in non-Caucasian women, the role of obesity at diagnosis is an important factor.

According to a 2010 medical review, obese women have a 30% higher risk of mortality after a diagnosis of breast cancer. On a biological level, it has been suggested that adipose tissue stimulates cancer cell growth leading to more aggressive tumors.

Furthermore, some new studies have shown that moderate exercise after breast cancer diagnosis may improve survival rates.

What better reason to lose weight and start that exercise program … Come on Girls!

Conclusions

It is safe to say that the reasons for the disparity amongst breast cancer mortality rates according to race are complex and interlinked.

There appears to be a combination of biological and environmental factors that all affect prognosis.

However, as research progresses, breakthroughs and improvements in survival will hopefully follow.

When I was poor and complained about inequality they said I was bitter. Now I’m rich and I complain about inequality they say I’m a hypocrite. I’m starting to think that they just don’t want to talk about inequality.

Here are some older graphs and dated information from our original post

We have left this information in because, although dated, it still holds some interest and value.

The chart below demonstrates the difference between the rate of invasive breast cancer and the mortality rate across various ethnic groups.

Clearly, the number of deaths due to breast cancer development, when compared to the invasive breast cancer incidence rate, is abnormally high for African American and Native American/Alaskan native women.

According to some estimates, the disparity between white women and African American women in terms of breast cancer mortality could be reduced by up to 70% if high quality treatment facilities were available to all women.

The average annual female breast cancer death rate in the U.S. is highest for African Americans, at about 36 per 100000 women.

It is also interesting to note that the breast cancer mortality rate is higher for Hispanic and American Indian/Alaskan natives than with Asian Americans and Pacific Islanders. This is in spite of a lower incidence rate among African Americans and American Indians/Alaskan natives.

Five year survival rates for local and node positive breast cancers

During the 1980s the mortality rates for white women and African American women was about the same. However, since 2000, African American women have an approximately 32% higher death rate from breast cancer.

The main reasons for this difference are suggested to be a more advanced breast tumor at the time of diagnosis. This may be due to non-participation in screening mammography and unequal access to prompt, high-quality treatment.

During the 1990s, the five-year survival rate after breast cancer diagnosis actually increased from 91% to over 97% for white women in the U.S. for ‘localized‘ breast cancer.

However, during the same period, the five year survival rate for local breast cancer increased from 85% to about 90% for African American women.

fiveyearsurvival-localbreastcancer-whiteblack

Rates of five-year survival for regionally advanced breast cancer increased from about 69% to over 80% for White women. For African American women 5-year survival only increased from 55% to 66%.

It is estimated that breast cancer screening and early detection programs aimed at helping low-income women in the U.S. actually only reach about 12% to 15% of uninsured women between the ages of 50 and 64.

Lower income women tend to have a more advanced breast tumor at the time of diagnosis. Also, there are frequently greater delays between first screening and definitive diagnosis.

For further reading, I suggest you visit our recent updated posts:-

REFERENCES:

Daly B, Olopade OI. (2015)Race, Ethnicity, and the Diagnosis of Breast Cancer. JAMA. 2015 Jan 13; 313(2): 141–142. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4504733/
DeSantis C, Ma J, Bryan L, Jemal A. (2010) Breast cancer statistics, 2013. CA: A Cancer Journal for Clinicians Volume 64, Issue 1. https://www.ncbi.nlm.nih.gov/pubmed/24114568

More references for this section are on this page .

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