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BREAST CANCER REVIEW

Breast Cancer in the U.S.

Introduction

The incidence of breast cancer in U.S. women has been gradually rising over the past two decades while, most recently, mortality rates have somewhat declined. However, both incidence and mortality differ substantially among women from different racial and ethnic groups. Additionally, studies show that socioeconomic factors contribute to disparities in breast cancer care. The reduction of these disparities is a primary and ongoing objective of leading public and private health organizations. At the same time, current medical research continues to build upon significant scientific advances, toward the collective vision of reducing the burden of breast cancer and improving outcomes for all.

Breast Cancer Facts

Breast cancer is the most common non-skin cancer among U.S. women. During 2006, an estimated 274,900 new cases will have been diagnosed: 212,920 invasive breast cancers and 61,980 cases of in situ carcinoma. Of these, an approximate 85% will be ductal carcinoma in situ.¹ If the current incidence rate stays the same, women born today have about a 1 in 8 chance of developing breast cancer at some point during their lives. Thirty years ago, the lifetime risk was just under 1 in 10.² Presently, there are over 2 million women living in the U.S. who have been diagnosed and treated for breast cancer^3, 4

Gender is the most important risk factor for breast cancer. While in any given year the disease will be diagnosed in a small number of men (1,720 new cases estimated for 2006), the number of women diagnosed with breast cancer will be 100 times greater.⁵ Age is the second most important risk factor; the majority of advanced breast cancer cases are diagnosed in women over 50.⁶ Other factors are also known to increase a woman's risk for the disease.⁷ However, most breast cancers occur in women with no apparent risk factors other than gender and age.

In recent decades, the overall trend of breast cancer incidence in the U.S. has been gradually upward. Through most of the 1980s, incidence rates rose sharply, as measured by an average annual increase of 3.7%.⁸ During the late 1980s and 1990s, the incidence rates slowed to an annual average increase of 0.4%.⁹ In the more recent time period, breast cancer incidence rates increased only in women aged 50 and older.¹⁰

Most experts attribute the overall rise in incidence to a combination of influences that include changes in women's reproductive patterns (i.e., delayed childbearing and having fewer children), improvements in imaging technology, and an increased use of screening mammography, which can detect breast cancer before it causes symptoms. Since 1980, the incidence of ductal carcinoma in situ (DCIS), one of the most common types of early stage breast cancers, has increased more than sevenfold.¹¹

As breast cancer incidence rates have risen, mortality rates from breast cancer have declined. Specifically, between 1990 and 2002, the mortality rate for women of all races combined declined by 2.3% annually, with larger decreases in women younger than 50.¹² These decreases are attributed to both earlier detection and improved treatments.¹³

Still, breast cancer remains the second leading cause of cancer death in U.S women, after lung cancer.¹⁴ According to the American Cancer Society, an estimated 40,970 U.S. women will have died from breast cancer in 2006.¹⁵ Based on the most recent data, 12% of women diagnosed with breast cancer die from the disease within five years. At ten years, the rate is 20%, at fifteen years, 29%, and at 20 years, the mortality rate for women diagnosed with breast cancer is nearly 40%.¹⁶ The key to surviving the disease is early detection. If detected early, the 5 year relative survival rate for localized breast cancer is 98%.¹⁷

Screening Guidelines

The American Cancer Society currently recommends that women begin getting an annual mammogram at age 40. Women at increased risk (e.g., family history, personal history of breast cancer, etc.) are encouraged to consult with healthcare providers about the benefits and limitations of earlier initiation of screening, shorter screening intervals, or the addition of screening modalities other than mammography and physical examination. Efforts aimed at increasing access to screening for more U.S. women are ongoing and hold promise for decreasing the number of future deaths due to breast cancer. The combined use of clinical breast examination, mammogram and breast self-examination is believed to offer the best opportunity for early detection. (For more information, please see Detection and Screening )

Racial and Ethnic Patterns

In the United States, breast cancer incidence rates differ substantially among women from different racial and ethnic groups.

Incidence is highest for White women, followed by African-American, Asian American/Pacific Island, Hispanic, and lastly, American Indian/Alaskan Native women.¹⁸ The incidence rate for the highest group (White) is two and a half times as great as that for the lowest group (American Indian/Alaskan Native). While reasons for these differences are not fully understood, potential explanations include differences in risk factor exposure, differences in genetics and/or biology, and differences in socioeconomic conditions.

Mortality rates among racial/ethnic groups have a different pattern of disparity than that observed for incidence.

Although incidence is highest for White women, African American women have the highest mortality rate, followed by White, Hispanic, Asian American/Pacific Island, and American Indian/Alaskan Native women.¹⁹ Additionally, for women with invasive breast cancer, the five-year survival rate for African Americans is just 76%, compared to a 90% five-year survival rate for Whites.²⁰ Moreover, between 1990 and 2002, as the mortality rate for women of all races combined declined by 2.3% annually, it declined by 2.4% annually in White women and just 1.0% annually for African American women.²¹

In a report on recent trends in U.S. mortality rates for four major cancers, including breast cancer, the Centers for Disease Control and Prevention (CDC) states that differences among racial/ethnic groups "result from a combination of factors such as behaviors (e.g. smoking and nutrition); access to preventive, diagnostic, therapeutic, and screening services; and aggressiveness of treatment."²² The CDC, which funds screening to underserved women through the National Breast and Cervical Cancer Early Detection Program, believes that modifying these factors could prevent more than half of the cancer deaths and eliminate most racial/ethnic disparities in cancer death rates.

Additionally, some researchers have highlighted differences in biology, especially in African American women, whose breast tumors often exhibit more aggressive characteristics. The prevalence of triple negative breast tumors among African American women, for instance, may be more than twice that as for White women.²³ Characterized by three biological components (i.e., negative for estrogen receptor, progesterone receptor, and HER2), these triple negative tumors are unresponsive to the most common and effective breast cancer treatments and are more likely to have poor prognosis.²⁴ In addition, relative to other racial/ethnic groups, African American women may have a higher prevalence of basal-like breast tumors - one of the more aggressive breast cancer subtypes for which there are currently no targeted treatments.²⁵

While these and other biological differences have been observed, it is important to note that they do not preclude the influence of social factors. As one health disparities researcher explains, biology is adaptive; it changes with changing environmental conditions.²⁶ As such, the finding of biological differences among groups living in different social conditions would not be unexpected.

Socioeconomic Factors

Among the U.S. population, 24% of African Americans and 22% of Hispanics currently live in poverty, compared with 8% of Whites.²⁷ Moreover, 20% of African Americans and 32% of Hispanics lack health insurance, while only 11% of Whites are uninsured.²⁸ According to the American Cancer Society, people living in poverty and those who lack health insurance are more likely to be diagnosed with advanced stage disease, more likely to receive substandard medical care, and more likely to die from cancer.²⁹

Indeed, factors associated with lower socioeconomic status (SES) may explain many of the differences observed in breast cancer incidence and mortality among racial and ethnic groups. In the case of screening, for example, data from 2003 show that White, African-American, and Hispanic women aged 40 and older were mammographically screened at similar rates (55.5%, 54.2% and 52.6%). Women with and without health insurance, however, were screened at remarkably different rates (58% vs. 28.9%).³⁰ Other research studies have linked lower levels of education to later stage diagnosis³¹ and have shown that low income, independent of race, is associated with inferior treatment (e.g., no surgery, or no radiation therapy after breast-conserving surgery).³² As the National Cancer Institute explains, "[S]tudies have found that SES, more than race, predicts the likelihood of a group’s access to education, certain occupations, and health insurance, as well as income level and living conditions -- all of which are associated with someone’s chance of developing and surviving cancer."³³

Additionally, socioeconomic factors can have an unwanted effect on provider/patient interactions. According to health researchers, some providers may withhold information if they think the patient won't understand. Likewise, physicians may not recommend a treatment to a patient that they think cannot afford it.³⁴ The message to healthcare providers is to be aware of these potential biases when interacting with patients and to treat all patients equally. The National Cancer Institute is clear on this issue: "equal care for cancer results in equal outcomes and equal survival rates...Conversely, unequal outcomes strongly suggest unequal care."³⁵

As the principal agency for cancer research in the U.S., the National Cancer Institute (NCI) supports scientific studies on socioeconomic factors and their relationship to cancer incidence, survival, and mortality. NCI also supports numerous intervention efforts, recognizing that the burden of cancer is too often greater for the poor, the uninsured, and for ethnic minorities. Indeed, the Center to Reduce Cancer Health Disparities (CRCHD) established in 2001, was created by NCI "to reduce, and ultimately, to end blatant injustices within the health care system."³⁶

In addressing disparity issues, the CRCHD considers the influence of financial and physical barriers, as well as barriers related to information and education, and those related to cultural differences and biases in cancer care.³⁷ An example comes from the CRCHD's Patient Navigator Program (PNP) which trains and assigns healthcare workers from local communities to help underserved patients overcome health system barriers to obtaining quality cancer care. For more information on Patient Navigator Programs, or for additional information about CRCHD's mission, strategies and objectives, please visit the CRCHD web site. 

Consumer Bill of Rights and Responsibilities

In 1998, The President's Advisory Commission on Consumer Protection and Quality in the Health Care Industry issued The Consumer Bill of Rights and Responsibilities as part of its final report entitled Quality First: Better Health Care for All Americans. The Consumer Bill of Rights, also called the Patient Bill of Rights, proposed eight principles which have been adopted by many U.S. health plans, including those sponsored by the federal government. The fifth principle deals with issues of respect and nondiscrimination, stating that consumers "have the right to considerate, respectful care from all members of the health care system at all times and under all circumstances." It also states that consumers "must not be discriminated against in the delivery of health care services consistent with the benefits covered in their policy or as required by law based on race, ethnicity, national origin, religion, sex, age, mental or physical disability, sexual orientation, genetic information, or source of payment."³⁸ Following is a summary of all eight principles contained within the Consumer Bill of Rights:³⁹

1. Information Disclosure. Consumers have the right to receive accurate, easily understood information, and some consumers require assistance in making informed health care decisions about their health plans, professionals and facilities.
2. Choice of Providers and Plans. Consumers have the right to a choice of health care providers that is sufficient to ensure access to appropriate high-quality health care.
3. Access to Emergency Services. Consumers have the right to access emergency health care services when and where the need arises.
4. Participation in Treatment Decisions. Consumers have the right and responsibility to fully participate in all decisions related to their health care. Consumers who are unable to fully participate in treatment decisions have the right to be represented by parents, guardians, family members, or other conservators.
5. Respect and Nondiscrimination. Consumers have the right to considerate, respectful care from all members of the health care industry at all times and under all circumstances.
6. Confidentiality of Health Information. Consumers have the right to communicate with health care providers in confidence and to have the confidentiality of their individually identifiable health care information protected. Consumers also have the right to review and copy their own medical records and request amendments to their records.
7. Complaints and Appeals. Consumers have the right to a fair and efficient process for resolving differences with their health plans, health care providers, and the institutions that serve them, including a rigorous system of internal review and an independent system of external review.
8. Consumer Responsibilities. In a health care system that protects consumers' rights, it is reasonable to expect and encourage consumers to assume reasonable responsibilities. Greater individual involvement by consumers in their care increases the likelihood of achieving the best outcomes and helps support a quality improvement, cost-conscious environment.

The full report to the President on the Consumer Bill of Rights and Responsibilities is available on the web site of The President's Advisory Commission on Consumer Protection and Quality in the Health Care Industry.

Current Research

Since the passage of the National Cancer Act in 1971,⁴⁰ the National Cancer Institute has led the nation's effort in supporting a wide range of scientific studies whose collective and ultimate mission is saving lives. In 1997, NCI assembled a multidisciplinary working group of scientists, clinicians, and advocates to help define a national research agenda for breast cancer. Seven years later, a separate NCI Breast Cancer Working Group was convened to assess the nation's progress. At the time of the 2004 assessment, the following initiatives were either in clinical trials or had been developed and approved.⁴¹

• Tamoxifen for the prevention of breast cancer in high-risk women
• Aromatase inhibitors for treatment of estrogen receptor-positive breast cancer
• Monoclonal antibodies for treatment of tumors that express Her2/ErbB2
• Sentinel node biopsy for less-invasive surgical diagnosis and prognosis
• Lumpectomy with radiation as an equivalent alternative to mastectomy for certain stages of disease
• Preoperative therapy to reduce the size of large tumors, thereby allowing more women to undergo breast-conserving surgery

Since 1998, NCI's breast cancer research investment has increased from $348.6 million⁴² to an estimated $560.1 million in 2005.⁴³ In FY 2005, the total dollars were distributed among seven scientific areas of interest as follows: biology (18%); etiology (18%); prevention (8%); early detection, diagnosis and prognosis (15%); treatment (23%); cancer control, survivorship, and outcomes research (15%); and lastly, scientific model systems (3%).⁴⁴ These seven areas, also called the Common Scientific Outline (CSO), continue to guide all NCI research today. Moreover, the CSO serves to facilitate coordination and comparison among public, private, national and international cancer research organizations. For descriptions of the CSO categories, as well as listings of current breast cancer research projects, funding opportunities, and resources, please refer to NCI's Cancer Research Portfolio web site.

In addition to government organizations, private organizations provide significant levels of support for breast cancer research in the U.S. The largest among these is the American Cancer Society (ACS), which, in August 2005, was funding 188 research projects relating to breast cancer, totaling more than $103.8 million. ACS also sponsors grants in support of training for health professionals seeking to develop their clinical expertise and/or their ability to conduct independent research. Select areas of breast cancer research currently being investigated by ACS grantees are listed as follows:⁴⁵

• the role of insurance and government policies in breast cancer screening among low-income women
• the psychological factors in chemotherapy-related fatigue
• the use of DNA microchips to identify genes involved in breast cancer development and progression
• how diet interacts with genetics to influence breast cancer risk
• the development of mouse models with human breast cancer genes to test drugs
• the mechanism of action of a new breast cancer therapeutic vaccine
• how an estrogen receptor-positive tumor becomes estrogen receptor-negative
• the quality of life among younger breast cancer survivors
• the possible effects of certain breast cancer treatments on thinking and memory

In addition to these, ACS notes a number of specific recent advances in breast cancer research that have led to improved methods across broad areas, including hormone therapy for prevention in high-risk women; MRI for use in breast biopsy procedures (allowing for many samples with one small incision); microvascular surgery and skin-sparing mastectomy (facilitating a more natural-looking breast in breast reconstruction); and in breast cancer treatment, the use of monoclonal antibodies (trastuzumab); more effective dosing methods with chemotherapy, and progress with antiangiogenesis therapy.⁴⁶ Additionally, the American Society of Clinical Oncology lists improvements in the delivery of radiation therapy, such as partial breast radiation, brachytherapy, and intensity-modulated radiation.⁴⁷

Lastly, NCI reminds that "the successful application of evidence-based interventions for preempting cancer through prevention, detection, diagnosis, and treatment depends on our ability to move effective interventions into practice."⁴⁸ Collaborative, multidisciplinary partnerships across public and private sectors help ensure that the beneficial results of breast cancer research are widely adopted by public health programs and clinical practices throughout the U.S., reaching as many people as possible.

Notes

¹American Cancer Society.Cancer Facts & Figures 2006. Retrieved Aug. 17, 2006 at: http://www.cancer.org/docroot/STT/content/STT_1x_Cancer_Facts__Figures_2006.asp

²National Cancer Institute. Probability of Breast Cancer in American Women (Apr. 15, 2005). Retrieved Aug. 17, 2006 at: http://www.cancer.gov/cancertopics/factsheet/Detection/ probability-breast-cancer

³American Cancer Society. How Many Women Get Breast Cancer? (Sep. 16, 2005). Retrieved Aug. 17, 2006 at: http://www.cancer.org/docroot/CRI/content/CRI_2_2_1X_How_many_ people _get_breast_cancer _5.asp?sitearea=

⁴Surveillance Epidemiology and End Results.Cancer Stat Fact Sheets: Cancer of the Breast. Retrieved Aug. 17, 2006 at: http://seer.cancer.gov/statfacts/html/breast.html?statfacts_ page= breast.html&x=14&y=17

⁵American Cancer Society. What Are the Key Statistics About Breast Cancer in Men? (Sep. 14, 2005). Retrieved Aug. 17, 2006 at: http://www.cancer.org/docroot/CRI/content/CRI_2_4_1X_What_ are_the_key_statistics_for_male_breast_cancer_28.asp?rnav=cri

⁶Medline Plus. Breast Cancer (Apr. 3, 2007). Retrieved Nov. 21, 2007 at: http://www.nlm.nih.gov/ medlineplus/ency/article/000913.htm

⁷In addition to gender and age, other risk factors for breast cancer include early onset of menses and late menopause; nulliparity or first full-term pregnancy after age 30; use of postmenopausal hormone replacement therapy; genetic factors; family history of breast cancer; high breast density; certain benign breast changes; a personal history of some cancers; high-dose radiation therapy to the chest; daily alcohol consumption; and obesity.

^8-9See note 4.

¹⁰American Cancer Society. Breast Cancer Facts & Figures 2005-2006. Retrieved Apr. 16, 2007 at: http://www.cancer.org/docroot/STT/content/STT_1x_Breast_Cancer_Facts__Figures_2005-2006.asp

¹¹Behind the Cancer Headlines. Early Stage Breast Cancer Rates are Rising as Incidence of Invasive Cases are Leveling (Apr. 14, 2005). Retrieved Apr. 18, 2006 at: http://www.mabcie.com/ April_14,_2005_breast_cancer.html

¹²See note 10.

¹³American Cancer Society. What Are the Key Statistics for Breast Cancer? (Sep. 2, 2005). Retrieved Aug. 17, 2006 at: http://www.cancer.org/docroot/CRI/content/CRI_2_4_1X_ What_ are_the_key_statistics_for_breast_cancer_5.asp?sitearea=

¹⁴See note 13.

¹⁵See note 1.

^16-17See note 10.

^18-19See note 1.

^20-21The American Cancer Society attributes these less favorable outcomes in African American women to later stage detection and poorer stage-specific survival. See note 11.

²²Centers for Disease Control and Prevention. Recent Trends in Mortality Rates for Four Major Cancers, by Sex and Race/Ethnicity --- United States, 1990--1998. (Jan, 2002). Retrieved Aug. 16, 2006 at: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5103a1.htm

²³ Behind the Cancer Headlines. Racial Differences in Triple Negative Breast Tumors Among Women in Atlanta (Apr. 10, 2006). Retrieved Aug. 18, 2006 at: http://www.mabcie.com/ April_10,_2006_breast_cancer.html

²⁴Steelquist, Colleen. Ethnic Differences in Breast-Cancer  (May 5, 2005). Retrieved Aug. 18, 2006 at: http://www.fhcrc.org/about/pubs/center_news/2005/may5/sart4.html

²⁵Behind the Cancer Headlines. Pre-menopausal African-American Women More Likely to Have Certain Type of Breast Cancer (Jun. 12, 2006). Retrieved Aug. 18, 2006 at: http://www.mabcie.com/ June_12, _2006 _breast_cancer.html

²⁶Behind the Cancer Headlines.Overcoming Racial and Ethnic Disparities in Healthcare (Feb. 28, 2005). Retrieved Aug. 18, 2006 at: http://www.mabcie.com/ February_28,_2005_breast_cancer.html

^27-29See note 1.

³⁰See note 10.

³¹American Cancer Society. Lower Education, Income Linked to Late Cancer Diagnosis (Feb. 20, 2002). Retrieved Aug. 10, 2006 at: http://www.cancer.org/docroot/NWS/content/NWS _1_1x_ Lower_Education_Income_Linked_to_Late_Cancer_Diagnosis.asp

³²American Cancer Society. Treatment for Breast Cancer Linked to Socioeconomic Status (Apr. 3, 2004). Retrieved Aug. 10, 2006 at: http://www.cancer.org/docroot/NWS/content/NWS _1_1x_ Treatment_for_Breast_Cancer_Linked_to_Socioeconomic_Status.asp

³³National Cancer Institute. Cancer Health Disparities: A Fact Sheet. (Nov. 30, 2005). Retrieved Apr. 16, 2007 at: http://www.cancer.gov/newscenter/benchmarks-vol5-issue6/page2

³⁴See note 31.

³⁵National Cancer Institute. Health Information Tip Sheet for Writers: Cancer Health Disparities. (updated, Nov. 30, 2005). Retrieved Aug. 15, 2005 at: http://www.cancer.gov/ newscenter/tip-sheet-cancer-health-disparities

³⁶Center to Reduce Cancer Health Disparities. Introduction to the Center. Retrieved Aug. 15, 2005 at: http://crchd.nci.nih.gov/introduction

³⁷See note 35.

³⁸Advisory Commission on Consumer Protection and Quality in the Health Care Industry.Consumer Bill of Rights and Responsibilities - Chapter Five: Respect and Nondiscrimination. Retrieved Aug. 25, 2005 at: http://www.hcqualitycommission.gov/cborr/chap5.html

³⁹Advisory Commission on Consumer Protection and Quality in the Health Care Industry. Consumer Bill of Rights and Responsibilities - Summary of the Document. Retrieved Aug. 25, 2005 at: http://www.hcqualitycommission.gov/press/cbor.html#head1

⁴⁰For information on The National Cancer Act of 1971, please see: Cancer Research.The 1971 National Cancer Act. Retrieved Aug. 15, 2005 at:http://rex.nci.nih.gov/massmedia/ CANCER_ RESRCH_WEBSITE/1971.html

^41-42National Cancer Institute. Breast Cancer Progress Report. (October 2004). Retrieved Aug. 15, 2005 at: http://planning.cancer.gov/pdfprgreports/2004breastcancer-pdf/allchapters.pdf

^43-44National Cancer Institute. A Snapshot of Breast Cancer. (Sep., 2006). Retrieved Apr. 16, 2007 at: http://planning.cancer.gov/disease/Breast-Snapshot.pdf

⁴⁵American Cancer Society. What Research Is Currently Being Done on Breast Cancer? Retrieved Aug. 16, 2006 at:http://www.cancer.org/docroot/CRI/content/CRI_2_6x_What_Research _Is_Currently_Being_Done_On_Breast_Cancer.asp?sitearea=

⁴⁶American Cancer Society. What's New in Breast Cancer Research? Retrieved Aug. 16, 2006 at: http://www.cancer.org/docroot/CRI/content/CRI_2_2_7X_ Whats_new_in_breast_cancer_ research_5.asp?sitearea=

⁴⁷People Living With Cancer (PLWC). Breast Cancer: Current Research. Retrieved Aug. 13, 2006 at: http://www.plwc.org/portal/site/PLWC/menuitem.6067beb2271039bcfd748f68ee37a01d/?vgnextoid= 6ec6ea7105daa010 VgnVCM100000ed730ad1RCRD&vgnextfmt=cancer

⁴⁸National Cancer Institute. Current NCI Portfolio. Retrieved January 31, 2007 at: http://plan2007.cancer.gov/currentNCIport.shtml

Updated: June 4, 2008.

Source URL: http://qap.sdsu.edu/education/bcrl/Bcrl_bcinus/bcrl_bcinus_index.html

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