Upon completion of the chapter, the reader will be able to:
Explain the relative importance of various risk factors.
Summarize the features of the four intrinsic breast cancer subtypes.
Articulate some of the reasons for improved patient survival.
Recognize signs and symptoms related to early and late stages of the disease.
Distinguish between good and poor prognostic factors.
Describe the roles of hormone and HER2 receptors.
Determine treatment goals for early stage, locally advanced, and metastatic breast cancers.
State the rationale for inclusion of adjuvant and neoadjuvant therapies.
Discuss the benefits and risks associated with various endocrine therapies.
List relevant factors that guide management and treatment of early and metastatic breast cancers.
Two breast cancer trends, the modest decline in new diagnoses and improvement of 5-year survival rates, have continued over the past decade. One factor that could be associated with both the former and latter findings is screening. The link to screening is plausible as detection of more patients with non-invasive (ie, in situ) disease could impact the number of new invasive breast cancer cases, while diagnosis of early-stage disease should translate to improved overall survival.
EPIDEMIOLOGY AND ETIOLOGY
Breast cancer is the most common type of cancer and second only to lung cancer as a cause of cancer death in American women. In 2015, female breast cancer will account for 99% of the projected 235,000 new cases; the median age at diagnosis will be 61 years; and approximately 40,000 deaths will occur as a result of the disease.1 KEY CONCEPT Even though the disease occurs more frequently in white women than any other ethnic group, the mortality rate is highest among African Americans.
Tumor size of most breast cancers at diagnosis is usually small (less than 2 cm); and early-stage disease predominates in all racial and ethnic groups. However, African American women have proportionally more cases of advanced disease compared with white women. It has been suggested that reduced access to proper medical care, including breast cancer screening programs, as well as certain biological factors, contribute to late diagnoses.
The etiology of breast cancer remains largely unknown though a number of factors have been associated with risk of developing the disease. Evidence also strongly suggests that breast cancer biology involves very complex interactions between sex hormones, genetic factors, environment, and lifestyle. The intrinsic and extrinsic components associated with the disease are discussed further.
KEY CONCEPT Aside from gender, the variable most strongly associated with breast cancer is age as disease risk and incidence increase with age. One of the most frequently quoted breast cancer statistic is the probability that one in eight will develop the disease. However, a more instructive way of explaining the age-related factor is shown in Table 89–1. Although the probability of ...