Regular mammograms are key to early detection

Breast cancer affects one in eight women in the U.S. and is the second most common type of cancer diagnosed in women, after skin cancer.

The good news is that breast cancer death rates slowly fell each year from 2008 to 2017. But more screening could help those rates drop faster.

How it happens

Breast cancer happens when cancerous cells form in the breast tissue. Health experts don't know exactly why cancerous cells form in the breast in some women but not others. However, they do know some of the risk factors, such as older age, smoking, and a family history of the disease.

Estimating risk

Some women who don't seem to have common risk factors may still develop the disease, while other women with a known risk factor may never develop it. This is why regular screening, such as mammograms, is key. Treatment for breast cancer is most effective and provides the best chance of survival when the disease is caught early.

Screening rates

Screening rates are increasing in some groups of women in the U.S. But for other groups, the rates are declining. According to the National Cancer Institute, screening rates have increased slightly among Hispanic women, but have dropped among other groups, including Asian women, women in rural areas, and women with public health insurance or no health insurance.

Who is more likely to get it?

• Breast cancer is most common in middle-aged and older women.
• Women aged 45 to 54 make up nearly 20% of new cases. Women aged 55 to 74 make up 51% of new cases.
• The rate of new cases of breast cancer is highest in white women, followed by African American women. Breast cancer death rates are highest for African American women—40% higher than for white women.

How to lower your risk

The key is to get regular exams and screening. You can't do much about risk factors like age or family history of breast cancer. But there are other things you can do. These include:

• Controlling your weight. Those who are obese have a 20% to 40% higher risk of developing breast cancer compared with women whose weight is in the normal range.
• Limiting alcohol. Even one daily drink can raise your risk.
• Getting regular exercise.
• Quitting smoking.

In the United States, women from diverse racial and ethnic groups continue to suffer from breast cancer disparities. African American and Hispanic/Latino women, in particular, experience a great burden from breast cancer (in incidence and mortality) compared to the general female population in the U.S.

For example:

• African American women diagnosed with breast cancer are less likely to survive five years after diagnosis (their survival rate is 71% compared to 81% survival rate of non-Hispanic White women).
• Breast cancer is the leading cause of cancer death among Hispanic and Latino women.

October 2, 2019, by NCI Staff

Men may be more likely than women to die after being diagnosed with breast cancer, particularly during the first 5 years after diagnosis, a new study suggests.

In the study, the 5-year overall survival rate after a diagnosis of breast cancer was 77.6% for men, compared with 86.4% for women, researchers reported in JAMA Oncology on September 19.

The findings add to previous research showing differences in death rates between men and women with breast cancer while also providing information about some of the factors that may contribute to the disparity between the sexes.

One factor identified by the authors was the lack of adequate treatment for many men with breast cancer, a phenomenon known as undertreatment. Another was the later diagnosis of the disease in men than in women.

Differences in clinical characteristics, such as the types and stage of breast tumors, age at diagnosis, and cancer treatment between men and women with breast cancer played a major role, accounting for 63% of mortality disparity, the researchers reported. However, after all those factors were accounted for, male patients still had 19% higher chance of dying than female patients within 5 years of diagnosis.

“We were not able to investigate other known or suspected contributors for the disparity in death rates in this study, such as compliance to cancer treatment, tumor genetics, and lifestyle factors, such as obesity, smoking, and alcohol use,” said Xiao-Ou Shu, M.D., Ph.D., of Vanderbilt-Ingram Cancer Center, who led the research.

“If we want to learn more about why outcomes of male breast cancer differ from those of female breast cancer, then we need more studies that focus on men with the disease,” Dr. Shu continued. These studies should include multiple outcomes, such as cancer remission, recurrence, and death rates from breast cancer and all causes, she added.

Focusing on Men with Breast Cancer

Fewer than 1% of breast cancers diagnosed each year occur in men, noted Alexandra Zimmer, M.D., of the Women’s Malignancies Branch in NCI’s Center for Cancer Research, who was not involved in the study.

“So far, we have been mostly lumping men with breast cancer and women with breast cancer in clinical trials and evaluations,” Dr. Zimmer said.

As a result, the treatment of male breast cancer has largely been based on studies involving women with the disease, she continued.

“The results of this retrospective study suggest that men with breast cancer deserve dedicated studies that will help us to better understand the biology of the disease in males,” Dr. Zimmer said.

Higher Death Rates, Later-Stage Cancers

To conduct the analysis, Dr. Shu and her colleagues used information from the National Cancer Database to compare death rates for 16,025 men and 1,800,708 women who were diagnosed with breast cancer between 2004 and 2014.

The National Cancer Database, which is sponsored by the American College of Surgeons and the American Cancer Society, includes more than 70% of newly diagnosed cancer cases in the United States.

In the study, men had higher death rates than women across all stages of breast cancer, even after the researchers adjusted for differences in patients’ clinical characteristics, such as the type and stage of disease, treatments received, age, race/ethnicity, and access to care.

In addition, the study found that a larger percentage of men than women were diagnosed with advanced-stage disease, which the researchers said could be attributed to a lack of awareness of and screening for breast cancer in men.

A higher percentage of men than women in the study had stage IV breast cancer at diagnosis (5.8% versus 3.8%), for example.

Despite having more aggressive disease overall, male patients were more likely than women to be undertreated, the researchers found. For instance, men were less likely than women to receive radiation therapy, including those who had breast-conserving surgery.

Clinical characteristics and undertreatment explained only about two-thirds of the difference in mortality. “Hopefully, future studies will be able to identify additional factors,” said Dr. Shu.

Unanswered Questions

As with all retrospective studies, Dr. Zimmer noted, the analysis had limitations. For example, the researchers lacked detailed information about treatment, such as which types of chemotherapy had been used.

What’s more, the National Cancer Database does not include information about the cause of death or the recurrence or progression of cancer.

“This study should be used mainly as a way to generate hypotheses for further studies, rather than to establish any firm conclusions at this point,” said Dr. Zimmer.

One of the messages of the study for men who are experiencing symptoms of breast cancer, she continued, “is to look for help and to consider treatment as soon as possible.”

Researchers have developed a new tool to estimate the risk of breast cancer in US Black women. The team that developed the tool hopes it will help guide more personalized decisions on when Black women—especially younger women—should begin breast cancer screening.

Compared with White women, Black women in the United States are younger at diagnosis, on average, and are more likely to be diagnosed with aggressive or advanced forms of breast cancer. They also are more likely to die from breast cancer than women of all other racial and ethnic groups.

These disparities, or inequalities, are thought to reflect the interplay of many factors, from tumor biology to matters like income, diet, access to quality health care, and other factors related to systemic and structural racism.

Called the Black Women’s Health Study Breast Cancer Risk Calculator, the new tool uses information on a woman’s medical, reproductive, and family history to estimate her chance of developing breast cancer over the next 5 or 10 years. This information is gathered from an online questionnaire that a woman and her health care provider can complete together.

Like other questionnaire-based breast cancer risk models, the new model is only moderately good at predicting whether or not an individual woman will go on to develop breast cancer, the researchers cautioned.

But it “could help guide decisions about whether Black women should consider screening for breast cancer [starting] at age 40 versus 50, or even earlier [than 40] if they have very high risk,” said Anne Marie McCarthy, Ph.D., of the Perelman School of Medicine at the University of Pennsylvania, who was not involved in the research.

“A major goal is for younger Black women to have a chance to have breast cancer detected and treated at early stages, so that fewer will die of the disease,” said Julie Palmer, Sc.D., of Boston University School of Medicine, who led the effort to develop the new model.

Published October 8 in the Journal of Clinical Oncology, the NCI-funded effort builds on previous models that estimate breast cancer risk in Black women, in large part by including additional risk factors.

Most existing models for calculating a woman’s risk of breast cancer were developed and tested with data mainly from White women and don’t work as well for Black women, Dr. Palmer said. “But for a long time, there weren’t enough data out there to develop and test a robust model for predicting breast cancer in Black women.”

“This [tool] helps address a critical gap in breast cancer risk prediction,” said Emily Conant, M.D., chief of breast imaging at the Hospital of the University of Pennsylvania, who was not involved with the work.

BWHS Breast Cancer Risk Calculator

This BWHS (Black Women’s Health Study) Breast Cancer Risk Calculator allows health professionals to estimate a woman’s risk of developing invasive breast cancer over the next 5 years. It was derived and tested solely in data from U.S. Black women. The tool uses a woman’s personal medical and reproductive history and the history of breast cancer and prostate cancer among her first-degree relatives (parents, siblings, children) to estimate absolute breast cancer risk—her chance or probability of developing breast cancer in a given period of time.

Although a woman’s risk may be accurately estimated, these predictions do not allow one to say precisely which woman will develop breast cancer. In fact, some women who do not develop breast cancer have higher risk estimates than some women who do develop breast cancer.

Early and increased clinical trial participation can help

 Worta McCaskill-Stevens, M.D., M.S., studies breast cancer's impact on diverse populations.

Worta McCaskill-Stevens, M.D., M.S., has spent much of her career advancing research that supports women with breast cancer, and the inclusion of underrepresented and underserved populations in clinical trials.

At the National Cancer Institute (NCI), Dr. McCaskill-Stevens explores how race impacts cancer outcomes, especially in African American women, who are 40% more likely to die from breast cancer than white women.   

As part of her work, Dr. McCaskill-Stevens helps oversee NCI breast cancer studies throughout the country. Most recently, she and her team at NCI helped launch a nationwide screening trial for breast cancer patients. They hope to better understand whether 3D mammography is better at diagnosing advanced breast cancers than the current 2D technology.

Why is this new screening trial so important? 

We haven't had a screening trial for decades. Women are being asked whether they want to have a new 3D mammogram instead of the older 2D one. We don't have the evidence that the more expensive [3D] technology is really better. This trial will help women make more informed decisions. It will look at whether 3D mammograms are better than 2D ones at finding advanced, life-threatening cancers over five years of screening. The trial will also provide us with more data to compare the risks of the two technologies. This includes whether a 3D mammogram's more complete view of the breast results in fewer or more false positives [when results say there is cancer when there actually isn't] than 2D does. If there's no difference, there would be limited data to support using the more costly screening procedure. 

Why are there continued differences among racial groups in breast cancer outcomes?

The racial disparity in terms of breast cancer death is continuing. African American women are about 40% more likely to die from breast cancer compared with white women, even though white women get breast cancer at a higher rate than African American women. Less access to medical care is a significant issue for African American women. They come into treatment very late in the disease, and their rate of aggressive, triple-negative breast cancer—the subtype with the poorest prognosis—is higher than in other racial groups.  

More minorities are being represented in clinical trials of breast cancer treatments. Why is that important? 

"African American women are about 40% more likely to die from breast cancer compared with white women."

- Worta McCaskill-Stevens, M.D., M.S.

It's very important. One of the reasons I came to NCI as a breast oncologist was to be able to look at racial disparities and see the differences in risk, screening, treatment, and survivorship. We are seeing that African American women's participation in breast cancer trials has increased. The trials have also changed. There are fewer very large trials and more focus on subtypes of cancer that are more aligned with higher incidence rates among African American women, especially triple-negative breast cancer. I am also encouraged that these women are joining the trials, because data suggest early treatment is more effective, especially for aggressive cancers.

Hispanic and Latina women have a lower death rate from breast cancer than white women, but breast cancer is still the leading cause of cancer deaths for those groups. Hispanic women and the general Hispanic population are younger than other racial and ethnic populations. Knowledge about screening, language barriers, and access to care are important factors to consider when thinking of Hispanic women. Communication to Hispanic women needs to consider the fact that it is a very diverse population with differences based upon country of origin and past knowledge about breast cancer.

NCI note: NCI places a high priority on answering the questions about optimal breast cancer screening and management, and has a working group to review accrual to the trial mentioned in this article, Tomosynthesis Mammographic Imaging Screening Trial (TMIST). During this review, the trial is fully open, both for women who are already participating and those who are interested in enrolling. New screening sites continue to open. NCI thanks the women who are and will be enrolled in TMIST for their participation.