DESCRIPTIVE EPIDEMIOLOGY OF BREAST CANCER

 DESCRIPTIVE EPIDEMIOLOGY OF BREAST CANCER

Sex:

• Excluding cancers of the skin, breast cancer is the most common cancer among women, accounting for nearly 1 in 4 cancers diagnosed in US women.
• Men are generally at low risk .
• Main Reason  women develop more breast cancer is because their breast cells are constantly exposed to the growth-promoting effects of the female hormones estrogen and progesterone.

Age:

• Breast cancer incidence and death rates generally increase with age .
• During 2002- 2006, 95% of new cases and 97% of breast cancer deaths occurred in women aged 40 and older.
• During 2002-2006, women aged 20-24 had the lowest incidence rate, 1.4 cases per 100,000 women; women aged 75-79 had the highest incidence rate, 441.9 cases  per 100,000.

• White women have a higher incidence of breast cancer than African American women beginning at age 45.
• In contrast, African American women have a higher incidence rate before age 45 and are more likely to die from breast cancer at every age.
• Breast cancer death rates are lower among white women than among African American women.
• Incidence and death rates for breast cancer are lower among women of other racial and ethnic groups than among white and African American women.

 
Tobacco smoke

• Most studies have found no link between cigarette smoking and breast cancer. Although some studies have suggested smoking increases the risk of breast cancer, this remains controversial.
• Potential carcinogens in tobacco smoke, such as N-nitrosamines, aromatic amines, and polycyclic aromatic hydrocarbons can raise a woman's risk of developing breast cancer.
•  Both mainstream and secondhand smoke contain chemicals that, in high concentrations, cause breast cancer in rodents.
• Chemicals in tobacco smoke reach breast tissue and are found in breast milk.
• One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers compared to those who are just exposed to secondhand smoke.
• A report from the California Environmental Protection Agency in 2005 concluded that the evidence about secondhand smoke and breast cancer is "consistent with a causal association" in younger, mainly pre-menopausal women.
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