Prevalence and Incidence of Breast Cancer

Prevalence/Incidence of Breast Cancer: Online Medical Books

16 MEDICAL BOOKS ONLINE! Review excerpts from medical books online, free, without registration, for more information about the prevalence and/or incidence of Breast Cancer.

Breast cancer: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

The cause of breast cancer isn't known, but its high incidence in women implicates estrogen.

Certain predisposing factors are clear; women at high risk include those who have a family history of breast cancer, particularly first-degree relatives (mother, sister, and maternal aunt).

Other women at high risk include those who:

❑have long menstrual cycles or began menses early (before age 12) or menopause late (after age 55)

❑have taken hormonal contraceptives

❑used hormone replacement therapy for more than 5 years

❑who took diethylstilbestrol to prevent miscarriage

❑have never been pregnant

❑were first pregnant after age 30

❑have had unilateral breast cancer

❑have had ovarian cancer — particularly at a young age

❑were exposed to low-level ionizing radiation.

Recently, scientists have discovered the BRCA1 and BRCA2 genes. Mutations in these genes are thought to be responsible for less than 10% of breast cancers. However, these discoveries have made genetic predisposition testing an option for women at high risk for breast cancer.

Women at lower risk include those who:

❑were pregnant before age 20

❑have had multiple pregnancies

❑are Native American or Asian.

Most breast cancer deaths occur in women age 50 and older (84% of cases), and 77% of new breast cancer cases occur in this age-group. However, it may develop any time after puberty. It occurs in men, but rarely; male cases of breast cancer account for less than 1% of all cases.

The 5-year survival rate for localized breast cancer has improved because of earlier diagnosis and the variety of treatments now available. According to the most recent data, mortality rates continue to decline in White women and, for the first time, are also declining in younger Black women. Lymph node involvement is the most valuable prognostic predictor. With adjuvant therapy, 70% to 75% of women with negative nodes will survive 10 years or more compared with 20% to 25% of women with positive nodes.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Malignant spinal neoplasms: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Primary tumors of the spinal cord may be extramedullary (occurring outside the spinal cord) or intramedullary (occurring within the cord itself). Extramedullary tumors may be intradural (meningiomas and schwannomas), which account for 60% of all primary malignant spinal cord neoplasms, or extradural (metastatic tumors from breasts, lungs, prostate, leukemia, or lymphomas), which account for 25% of these malignant neoplasms.

Intramedullary tumors, or gliomas (astrocytomas or ependymomas), are comparatively rare, accounting for only about 10%. In children, they're low-grade astrocytomas.

Spinal cord tumors are rare compared with intracranial tumors (ratio of 1:4). They occur equally in men and women, with the exception of meningiomas, which occur mostly in women. Spinal cord tumors can occur anywhere along the length of the cord or its roots.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

Mastitis and breast engorgement: Causes and incidence
(Professional Guide to Diseases (Eighth Edition))

Mastitis develops when a pathogen that typically originates in the nursing infant’s nose or pharynx invades breast tissue through a fissured or cracked nipple and disrupts normal lactation. The most common pathogen of this type is Staphylococcus aureus; less frequently, it’s S. epidermidis or beta-hemolytic streptococci. Rarely, mastitis may result from disseminated tuberculosis or the mumps virus. Predisposing factors include a fissure or abrasion on the nipple; blocked milk ducts; and an incomplete let-down reflex, usually due to emotional trauma. Blocked milk ducts can result from a tight bra or prolonged intervals between breast-feedings. Causes of breast engorgement include venous and lymphatic stasis, and alveolar milk accumulation. (See Physiology of lactation, page 982.)

Mastitis occurs postpartum in about 1% of pregnant women, mainly in primiparas who are breast-feeding. It occurs occasionally in nonlactating females and rarely in males. All breast-feeding mothers develop some degree of engorgement, which isn’t an infectious process.

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Source: Professional Guide to Diseases (Eighth Edition), 2005

About prevalence and incidence statistics:

The term 'prevalence' of Breast Cancer usually refers to the estimated population of people who are managing Breast Cancer at any given time. The term 'incidence' of Breast Cancer refers to the annual diagnosis rate, or the number of new cases of Breast Cancer diagnosed each year. Hence, these two statistics types can differ: a short-lived disease like flu can have high annual incidence but low prevalence, but a life-long disease like diabetes has a low annual incidence but high prevalence. For more information see about prevalence and incidence statistics.