context: Women in the U. S. have a 1 in 8 chance of developing an invasive form of breast cancer during their lifetime. When breast cancer is invasive, it starts in the breast ducts or glands but grows into breast tissue. It can then spread into the nearby lymph nodes and beyond. There are effective treatments. Your own treatment will depend on what type you have and how much and where your cancer has spread. You'll work together with your doctor to come up with a plan that's best for you. Two types account for about 90% of invasive breast cancer. Invasive ductal carcinoma ( IDC). This is the most common type, making up about 80%. With IDC, cancer cells start in a milk duct, break through the walls, and invade breast tissue. It can remain localized, which means it stays near the site where the tumor started. Or cancer cells may spread anywhere in the body. Invasive lobular carcinoma ( ILC). This type accounts for about 10% of invasive breast cancers. ILC starts in the lobules or milk glands and then spreads. With ILC, most women feel a thickening instead of a lump in their breast. Some women may have a combination of both or a different type of invasive breast cancer. Breast cancer may have no signs or symptoms, especially during the early stages. As the cancer grows, you may notice one or more of the following: A lump or thickening in or near the breast or in the underarm that continues after your monthly menstrual cycle A mass or lump, which may feel as small as a pea A change in the size, shape, or contour of the breast A blood-stained or clear fluid from the nipple A change in the feel or appearance of the skin on the breast or nipple -- dimpled, puckered, scaly, or inflamed Redness of the skin on the breast or nipple A change in shape or position of the nipple An area that is distinctly different from any other area on either breast A marble-like hardened area under the skin You may notice changes when you do a monthly breast self-exam. By doing a regular self-check of your breast, you can become familiar with the normal changes in your breasts. There's no way to know if you'll develop an invasive form of breast cancer, but there are things that increase your chances, many of which you can't change. Older women are at higher risk. About 10% of women diagnosed with invasive breast cancer are under age 45. And 2 out of every 3 women with invasive breast cancer are age 55 or older when they're first diagnosed. Your genetics and family history of breast cancer play roles. It's more common among white women than black, Asian, or Hispanic women. Also, you're at higher risk if you're obese, your breasts are dense, you didn't have children, or you became pregnant after the age of 35. After surgery to remove the tumor, a doctor will check it and assign a grade to it. The grade depends on how closely the cancer cells resemble normal cells when viewed under a microscope. Low-grade cancer cells are similar to normal breast cells. Higher grade breast cancer cells look more different. They show the cancer is more aggressive. The doctor will also test for estrogen receptors and progesterone receptors. This test will show whether the female hormones -- estrogen and progesterone -- influence the cancer cells. If the test is positive, it means hormones cause the cancer cells to grow. In that case, therapies to suppress or block hormones may help treat the cancer. The cancer will also be tested for a gene called HER2. If it's found, additional drugs like trastuzumab ( Herceptin) can be used. Other tests will see if the cancer has spread from the breast to other areas of the body. Different things will determine the type of breast cancer treatment your doctor recommends, including: Size of the tumor Location of the tumor Results of lab tests done on the cancer cells Stage of the cancer Your age and general health If you've been through menopause Your own feelings about the treatment options Family history Results of tests for a gene mutation that would increase the risk of breast cancer There are many treatments for invasive breast cancer. They include: Surgery. A lumpectomy is a surgical procedure in which a surgeon removes the cancer and a small area of healthy tissue around it. A mastectomy may be performed after chemotherapy. This procedure removes all of your breast. Chemotherapy. This drug treatment may be done before surgery to shrink the tumor and make the cancer operable. It's also sometimes given after surgery to try to prevent he cancer from coming back. Radiation . Often, radiation treatments are given after chemotherapy and surgery to prevent the cancer from coming back. Hormone therapy. Certain medications may be given if the cancer cells have hormone receptors. Targeted therapy. If the cancer cells have the gene HER2, you may be given drug treatments specifically for that. The goal of your treatment is to give you the best possible outcome. Your doctor may use one or a combination of them. Some women with invasive breast cancer choose to be part of a clinical trial. These trials test new drugs or treatment combinations to see if they are safe and if they work. And they're often a way for people to try new medicine that isn't available to everyone. Your doctor can tell you if one of these trials might be a good fit for you. Women with invasive breast cancer have more promise for a good outcome than ever before. Talk to your doctor to determine the best course of treatment for your situation.