It’s often impossible to say why one woman gets breast cancer and another doesn’t. And many known risk factors - a family history of breast cancer or a genetic mutation - can’t be controlled.

But women can control or change some risk factors. Even when risk can’t be reduced, understanding the risks can help women take steps to detect the disease early at highly treatable stages.

The October issue of Mayo Clinic Women’s HealthSource outlines the best defenses against breast cancer:

Notice change: When women are familiar with how their breasts look and feel, they are more aware of changes such as lumps, thickening tissue, skin redness or dimpling that should be discussed with a physician.

Get regular screenings: Clinical breast exams, in which the doctor looks for these changes, are recommended every three years for women in their 20s and 30s and annually for those in their 40s. Annual screening mammograms are recommended for women age 40 and older. This screening often finds tumors before they can be felt.

Some women are advised to be especially vigilant about screenings. Women who previously had breast cancer are at increased risk of developing a second breast cancer. Some benign breast conditions found during biopsies also are associated with an increased risk of getting breast cancer later. Increasingly, dense breasts are thought to increase breast cancer risk. Digital mammography or other specialized imaging could be recommended in these cases.

Consider preventive treatment: About 15 percent to 20 percent of breast cancers occur in women with some family history of the disease. Generally, the more relatives a woman has who were diagnosed with breast cancer before menopause or age 50, the higher the risk. Those at high risk can consider chemoprevention, which involves drugs such as tamoxifen. This can reduce the risk of breast cancer in women at high risk by 50 percent. Some women opt for surgeries to remove one or both breasts, which reduces breast cancer risk by 90 percent.

Be informed about hormone therapy: Short-term use of hormone therapy for menopause symptoms is reasonably safe. But studies have found the risk of breast cancer may increase when women take the combination of estrogen and progesterone for four or more years.

Make healthy lifestyle choices: Obesity, drinking excessive alcohol and unhealthy lifestyle habits are believed to have some impact on breast cancer risk. To minimize risk, women should maintain a healthy weight, be physically active, eat a healthy diet, stop smoking and limit alcohol consumption to one drink a day or less.

Source: Mayo Clinic