NURS 443 Lecture Notes - Lecture 12: Menarche, Cardiotoxicity, Breast Self-Examination
Breast Cancer
Breast cancer is the most common malignancy in American women except for skin cancer. It is second only to lung
cancer as the leading cause of death from cancer in women. In the United States more than 230,480 new cases of
invasive breast cancer and more than 57,650 cases of in situ breast cancer are diagnosed annually.1 About 2140 of
those new cases are diagnosed in men. Approximately 39,920 deaths (39,510 women and 410 men) occur each year
related to breast cancer.
The incidence of breast cancer is slowly decreasing, with a slight drop in the number of deaths related to breast
cancer. This decline may be the result of the decreased use of hormone therapy after menopause.2 Approximately
2.6 million women are alive in the United States today who are breast cancer survivors.
Patients diagnosed with localized breast cancer with no axillary node involvement have a 5-year survival rate of
98%. Conversely, only 23% of patients diagnosed with advanced-stage breast cancer with metastases to distant sites
will survive 5 years or more.1,2
Etiology and Risk Factors
Although the etiology is not completely understood, a number of risk factors are related to breast cancer (Table 52-
2). Risk factors appear to be cumulative and interacting. Therefore the presence of multiple risk factors may greatly
increase the overall risk, especially for people with a positive family history.
Risk Factors for Women.
The risk factors most associated with breast cancer include female gender and advancing age. Women are at far
greater risk than men, with 99% of breast cancers occurring in women. Increasing age also increases the risk of
developing breast cancer. The incidence of breast cancer in women under 25 years of age is very low and increases
gradually until age 60. After age 60, the incidence increases dramatically.
Hormonal regulation of the breast is related to the development of breast cancer, but the mechanisms are poorly
understood. The hormones estrogen and progesterone may act as tumor promoters to stimulate breast cancer growth
if malignant changes in the cells have already occurred. The Women's Health Initiative study showed that the use of
combined hormone therapy (estrogen plus progesterone) increases the risk of breast cancer and also the risk of
having a larger, more advanced breast cancer at diagnosis.15 The use of estrogen therapy alone for longer than 10
years (for women with a prior hysterectomy) increases a woman's long-term risk for breast cancer. A link may exist
between recent oral contraceptive use and increased risk of breast cancer for younger women.16
Modifiable risk factors include excess weight gain during adulthood, sedentary lifestyle, smoking, dietary fat intake,
obesity, and alcohol intake.10 Environmental factors such as radiation exposure may also play a role.
TABLE 52-2 RISK FACTORS FOR BREAST CANCER
Risk Factor
Comments
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Female
Women account for 99% of breast cancer cases.
Age ≥50 yr
Majority of breast cancers are found in postmenopausal women.
After age 60, increase in incidence.
Hormone use
Use of estrogen and/or progesterone as hormone therapy,
especially in postmenopausal women.
Family history
Breast cancer in a first-degree relative, particularly when
premenopausal or bilateral, increases risk.
Genetic factors
Gene mutations (BRCA1 or BRCA2) play a role in 5%-10% of
breast cancer cases.
Personal history of breast cancer, colon cancer,
endometrial cancer, ovarian cancer
Personal history significantly increases risk of breast cancer, risk
of cancer in other breast, and recurrence.
Early menarche (before age 12), late menopause
(after age 55)
A long menstrual history increases the risk of breast cancer.
First full-term pregnancy after age 30, nulliparity
Prolonged exposure to unopposed estrogen increases risk for
breast cancer.
Benign breast disease with atypical epithelial
hyperplasia, lobular carcinoma in situ
Atypical changes in breast biopsy increase the risk of breast
cancer.
Dense breast tissue
Mammograms harder to read and interpret. Dense tissue may be
associated with more aggressive tumors.
Weight gain and obesity after menopause
Fat cells store estrogen, which increases the likelihood of
developing breast cancer.
Exposure to ionizing radiation
Radiation damages DNA (e.g., prior treatment for Hodgkin's
lymphoma).
Alcohol consumption
Women who drink ≥1 alcoholic beverage per day have an
increased risk of breast cancer.
Physical inactivity
Breast cancer risk is decreased in physically active women.
Genetic Link
Family history of breast cancer is an important risk factor, especially if the involved family member also had ovarian
cancer, was premenopausal, had bilateral breast cancer, or is a first-degree relative (i.e., mother, sister, daughter).
Having any first-degree relative with breast cancer increases a woman's risk of breast cancer 1.5 to 3 times,
depending on age. A breast cancer risk assessment tool for health care providers is available through the National
Cancer Institute (seeResources at the end of this chapter). About 5% to 10% of all breast cancers are hereditary.
This means that specific genetic abnormalities that contribute to the development of breast cancer have been
inherited (passed from parent to child). Most inherited cases of breast cancer are associated with mutations in two
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genes: BRCA1 and BRCA2 (BRCA stands for BReast CAncer). Everyone hasBRCA genes. The BRCA1 gene, located
on chromosome 17, is a tumor suppressor gene that inhibits tumor development when functioning
Genetics in Clinical Practice
Breast Cancer
Genetic Basis
● • Mutations occur in BRCA1 and/or BRCA2 genes.
● • Normally these genes are tumor suppressor genes involved in DNA repair.
● • Transmission is autosomal dominant.
Incidence
● • Approximately 5% to 10% of breast cancers are related to BRCA1 and BRCA2 gene mutations.
● • Women with BRCA1 and BRCA2 gene mutations have a 40% to 80% lifetime risk of developing
breast cancer.
● • BRCA1 and BRCA2 gene mutations are associated with early-onset breast cancer that is more likely to
involve both breasts.
● • Men with mutations in BRCA1 and BRCA2 have an increased risk of breast cancer and prostate
cancer.
● • Family history of both breast and ovarian cancer increases the risk of having a BRCAmutation.
Genetic Testing
● • DNA testing is available for BRCA1 and BRCA2 gene mutations.
Clinical Implications
● • Most breast cancers (about 90%-95%) are not inherited. They are associated with genetic changes that
occur after a person is born (somatic mutations). There is no risk of passing on the mutated gene to
children.
● • Bilateral oophorectomy and/or bilateral mastectomy reduces the risk of breast cancer in women with
BRCA1 and BRCA2 mutations.
● • Mutations in the BRCA1 and BRCA2 genes increase the risk of ovarian cancer.
● • Genetic counseling and testing for BRCA mutations should be considered for women whose personal
or family history puts them at high risk for a genetic predisposition to breast cancer.
BRCA, BReast CAncer.
normally. Women who have BRCA1 mutations have a 40% to 80% lifetime chance of developing breast cancer. The
BRCA2 gene, located on chromosome 11, is another tumor suppressor gene. Women with a mutation of this gene
have a similar risk of breast cancer.
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Document Summary
Breast cancer is the most common malignancy in american women except for skin cancer. It is second only to lung cancer as the leading cause of death from cancer in women. In the united states more than 230,480 new cases of invasive breast cancer and more than 57,650 cases of in situ breast cancer are diagnosed annually. 1 about 2140 of those new cases are diagnosed in men. Approximately 39,920 deaths (39,510 women and 410 men) occur each year related to breast cancer. The incidence of breast cancer is slowly decreasing, with a slight drop in the number of deaths related to breast cancer. This decline may be the result of the decreased use of hormone therapy after menopause. 2 approximately. 2. 6 million women are alive in the united states today who are breast cancer survivors. Patients diagnosed with localized breast cancer with no axillary node involvement have a 5-year survival rate of.
