Epidemiologic reviews, 1993
The most common cancer in US women and the 2nd leading cause of cancer death is breast cancer.
Between 1980-1987 in the US. age-adjusted incidence rates of breast cancer rose rapidly. They are also rising rapidly in several Asian countries (e.g., in Japan) which have the lowest incidence rates. These rapid increases may mean that environmental factors are responsible.
Incidence rates rise greatly with age until the late 40s. US women at highest risk of breast cancer are Jewish women, urban women, single women, and women living in the northern US. Women at lowest risk include Mormon and Seventh-Day Adventist women, Hispanic and Asian women, rural women, women living in the southern US, and married women.
Factors that have a relative risk greater than 2 are
- mother and sister with history of breast cancer, especially if diagnoses at an early age;
- atypical epithelial cells in nipple aspirate fluid;
- nodular densities on the mammogram;
- history of cancer in 1 breast;
- mother or sister with history of breast cancer;
- biopsy-confirmed benign proliferative breast disease;
- hyperplastic epithelial cells without atypia in nipple aspirate fluid;
- and radiation to chest in moderate to high doses.
Ovarian hormones appear to stimulate cell division in the breast, thus elevated levels may be risk factors.
Exogenous hormones may also increase the risk. Women are exposed to these exogenous hormones through
- estrogen replacement therapy,
- progestin only pills,
- oral contraceptives,
- long-acting injectable contraceptives,
- and diethylstilbestrol.
Postmenopausal obesity increases the risk while premenopausal obesity decreases the risk. A high fat diet in childhood and adolescence may increase the risk. Alcohol drinking may also increase the risk.
Older, white, and nulliparous women are more likely to have estrogen receptor-positive cancers.
Breast cancer in males tends to share the same risk factors as well as its own unique factors.
Prevention of postmenopausal obesity is the only established primary prevention effort. Screening is the only secondary prevention means.
- Breast cancer epidemiology: summary and future directions, Epidemiologic reviews, NCBI PubMed PMID: 8405209, 1993.
- Featured image Mārtiņš Zemlickis.