Invasive breast cancer begins in the ducts or glands of the breast, but can grow into the breast tissue and then may metastasize to nearby lymph nodes and beyond. There are a number of effective treatments available, and treatment will depend on the type of cancer present, the extent of metastasis, and the site of metastasis. Patients will work with their doctors to develop a treatment plan that is best for them.
Types of invasive breast cancer
The following two types account for about 90% of invasive breast cancer:
- Invasive ductal carcinoma (IDC). This is the most common type, accounting for about 80% of cases. The cancer starts in one duct, passes through the duct wall, and invades the breast tissue. The tumor may be confined, staying close to where it started, or the cancer may spread anywhere in the body.
- Invasive lobular carcinoma (ILC). This type accounts for about 10% of invasive breast cancer. ILC starts in the lobules or breast and spreads. Most ILC feels like a thickening in the breast rather than a mass.
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Some women may have both of these types of cancer, or a different type of invasive breast cancer.
What are the signs of invasive breast cancer?
Breast cancer may have no signs or symptoms, especially in the early stages. As the cancer grows, one or more of the following manifestations may occur:
- Lumps or thickening in, near, or under the breast that persist after each menstrual cycle
- Lumps or swellings may feel as small as a pea
- Change in size, shape, or contour of the breast
- The nipple is leaking blood or clear fluid
- Changes in the feel or appearance of the skin of the breast or nipple that are indented, wrinkled, scaly, or inflamed.
- Redness of the skin of the breast or nipple
- Change in nipple shape or position
- A distinctly different area on either breast from the rest
- Hardened areas under the skin that look like marble
Patients may notice changes when they perform monthly breast self-exams. Regular self-examination of the breasts allows familiarization with normal breast changes.
What increases the risk of invasive breast cancer?
There is no way to know if a person will develop invasive breast cancer, but there are a number of factors that increase the odds, many of which you cannot change on your own.
Women who are older are at increased risk. About 10% of women diagnosed with invasive breast cancer are under the age of 45. About 2/3 of women with invasive breast cancer are diagnosed for the first time at age 55 or older.
Genetics and family history of breast cancer have an impact, and breast cancer is more common in white women than in black, Asian, or Hispanic women.
Also, there is an increased risk if there is obesity, dense breasts, no history of childbearing, or pregnancy after age 35.
What is tumor staging?
After tumor removal surgery, your doctor will examine the tumor to determine its stage. Tumor staging depends on how similar the cancer cells look to normal cells under the microscope. Low-stage cancer cells look similar to normal breast cells, while high-stage breast cancer cells look more different, indicating that the cancer is more aggressive.
Doctors will also test for estrogen receptors and progesterone receptors, which reflect whether the woman’s hormones estrogen and progesterone can affect cancer cells. If the test is positive, the hormones encourage cancer cell growth, and therapies that inhibit or block the hormones may help treat the cancer.
Tumors will also be tested for human epidermal growth factor receptor-2 (HER-2), and those who are positive can usually be treated with drugs such as trastuzumab.
There are other tests designed to see if the cancer has spread from the breast to other parts of the body.
How is invasive breast cancer treated?
The following factors determine what breast cancer treatment options your doctor recommends, including:
- Size of the tumor
- Location of the tumor
- Results of laboratory testing for cancer cells
- Stage of the cancer
- Patient’s age and general health status
- Whether the patient is menopausal
- Patient’s own opinion on treatment options
- Family history
- Test results for genetic mutations that may increase the risk of breast cancer
Treatment options for invasive breast cancer include:
- Surgery. Mastectomy removes only the tumor and a small amount of healthy tissue around it. Mastectomy can be performed after chemotherapy and will remove all of the patient’s breast tissue.
- Chemotherapy. Chemotherapy can be given before surgery to shrink the tumor and make the cancer potentially amenable to surgical removal. Sometimes chemotherapy is also given after surgery to prevent the cancer from coming back.
- Radiotherapy. Usually, radiation therapy is given after chemotherapy and surgery to prevent the cancer from coming back.
- Endocrine therapy. If the cancer has hormone receptors, some endocrine therapy drugs may be given.
- Targeted therapy. If the cancer has HER-2, the patient may be given drugs that target this target.
Treatment is designed to provide the best possible outcome. The doctor may recommend one therapy or a combination of therapies.
Some patients with invasive breast cancer choose to participate in clinical trials. These trials are designed to test some new drug or new combination of treatments to see if they are safe and effective. By participating in a clinical trial, patients can try a new drug that is not yet generally available. The doctor will inform the patient if there is a clinical trial that is appropriate for him or her to participate in.
Patients with invasive breast cancer will want to get good results and can talk with their doctor to determine the best treatment for their situation.