Invasive lobular carcinoma is a type of breast cancer that begins in the milk-producing glands (lobules) and then invades surrounding tissues. About 20,000 women are diagnosed with this type of breast cancer each year in the United States. Invasive lobular carcinoma makes up about 15 percent to 20 percent of all breast cancers.
Compared to the more common form of invasive breast cancer — invasive ductal carcinoma — invasive lobular carcinoma is less likely to show up on a mammogram. Although invasive lobular carcinoma tends to be larger at diagnosis, it generally has a more favorable outlook than does invasive ductal carcinoma.
Rather than forming a distinct lump you can feel, invasive lobular carcinoma (ILC) may simply feel like a thickened area in your breast. Lobular carcinoma cells tend to break out of the lobule in single file, then invade surrounding breast tissue in a web-like manner. The affected area may have a different textural feel from normal breast tissue, but it is unlikely to be a discrete mass.
As a result, an invasive lobular carcinoma might become fairly large — about 3/4 inch (2 centimeters) to about 2 inches (5 centimeters) or bigger — before any signs or symptoms appear. These might include:
- An area of thickening in part of the breast
- A new area of fullness or swelling in the breast
- A change in the texture or appearance of the skin overlying the breast, such as dimpling or thickening
- An inward-turning nipple (nipple retraction)
Invasive lobular carcinoma starts when cells in one or more milk-producing glands of the breast start growing abnormally. The cells divide more rapidly than normal cells do. When these abnormal cells stay within the lobule, the condition is referred to as lobular carcinoma in situ (LCIS) and is considered a marker for increased risk of breast cancer. At some point, abnormal cells may break out of the lobules and invade or “infiltrate” the surrounding tissue, becoming ILC.
About half the lobular breast cancers involve alterations (mutations) in a gene called E-cadherin (CDH1). This gene controls the activity of a protein that helps keep tumor cells from invading normal tissue and spreading. Some scientists believe that the turning off of E-cadherin sets the stage for ILC to develop. When lobular carcinoma is diagnosed, a laboratory doctor (pathologist) may order an E-cadherin protein study on the tissue to help differentiate ILC from LCIS.
A risk factor is anything that makes it more likely you’ll get a particular disease. But having one or even several risk factors doesn’t mean you’ll get cancer.
- Your gender. Being female is the single most significant risk factor for any type of breast cancer.
- Lobular carcinoma in situ. Women with LCIS — abnormal cells within breast lobules — face a higher risk of developing invasive cancer later, in either breast. LCIS is a marker indicating an increased risk of developing breast cancer but it’s not a cancer in itself.
- Older age. Women diagnosed with ILC typically are older than those with invasive ductal carcinoma (IDC). The median age at diagnosis for ILC is in the early 60s, compared with the mid- to late 50s for IDC.
- Postmenopausal hormone use. Use of the female hormones estrogen and progesterone during and after menopause has been shown to increase the risk of ILC. Researchers believe the hormones may stimulate tumor growth and also make tumors more difficult to see on mammograms. Although studies in the 1990s found a correlation between rising rates of ILC and use of hormone therapy, newer hormone regimens, including lower dose combinations, haven’t been assessed.
- Genetic cancer susceptibility. Women with a rare inherited condition called hereditary diffuse gastric cancer syndrome have an increased risk of getting both stomach (gastric) cancer and lobular breast cancer. Women with this condition run a 20 percent to 40 percent risk of developing lobular breast cancer during their life.
See your doctor if you notice any changes in the appearance or feel of your breast, including a new fullness or area of thickening. Although most breast changes aren’t cancerous, it’s important to have them evaluated promptly. In addition, talk to your doctor about following an individualized breast cancer screening program based on your family history and other risk factors.
Early diagnosis of ILC can be challenging. A mammogram, which takes X-ray images of your breast tissue, may not detect ILC early in the cancer’s development.
Your doctor may use a mammogram or a breast ultrasound (ultrasonography) to evaluate an abnormality found during a physical exam or seen on a screening mammogram. Ultrasound uses sound waves to produce images of structures deep within the body. Ultrasound tends to be better than mammography at detecting ILC, but may also underestimate the size of the tumor.
At the time of diagnosis and before surgery, your doctor may order magnetic resonance imaging (MRI) of the breast to evaluate the extent of the breast cancer and help with surgical management decisions. Breast MRI uses a magnet and radio waves to take pictures of the breast’s interior.
The diagnosis of ILC can only be made by biopsy — removing samples of breast tissue for analysis in the laboratory. If the biopsy results confirm that you have ILC, the next step is to determine how advanced your cancer is — its stage, or extent and severity.
Cancer cells removed in a biopsy will also be tested for the presence or absence of receptors for estrogen and progesterone. ILC is almost always estrogen receptor positive, which means it may be treated with drugs that alter hormone interactions with the cancer cells.
ILC is more likely than IDC to occur in both breasts — about 20 percent of women with ILC in one breast will also have it in the other one.
ILC is slow to spread outside the breast (metastasize). If the cancer does spread, it may show up in the gastrointestinal tract, the lining of the abdomen or the ovaries.
Treatment of ILC consists of surgery and additional (adjuvant) therapy, which may include chemotherapy, radiation and hormone therapy. At the time of the breast cancer surgery, the lymph nodes under your arm are also evaluated using the sentinel node technique. The sentinel lymph nodes are the first lymph nodes to receive drainage from breast tumors, and if they test negative for cancer cells, the cancer likely hasn’t spread outside the breast. If the sentinel lymph nodes are positive for cancer, then the surgeon will discuss removing additional lymph nodes, a procedure known as an axillary node dissection.
If the tumor is large relative to the size of your breast and you’re hoping to have breast-sparing surgery, your surgeon may recommend chemotherapy before surgery (neoadjuvant chemotherapy) to shrink the tumor. After you’ve completed this initial chemotherapy, your surgeon will then decide if breast-conserving surgery is an option.
It’s sometimes possible to remove early-stage ILC with a breast-sparing operation known as lumpectomy or wide local excision. The surgeon will remove the tumor itself, as well as a margin of normal tissue surrounding the tumor to make sure all the cancer that can be removed is taken out. Negative or “clean” margins reduce the chance of leaving any cancer in the breast. If the margins are positive, you may need additional surgery until negative margins are achieved, or the surgeon may decide to perform a mastectomy.
Chemotherapy uses drugs to destroy cancer cells. Treatment often involves receiving two or more drugs in different combinations. You may have four to eight treatments or “cycles” spread over three to six months.
After a lumpectomy, a course of radiation therapy is given to kill any remaining cancer cells in the breast and under your arm. This can help decrease the chance of cancer coming back in the area. Radiation typically involves about 30 treatments over six weeks and begins about three to four weeks after the lumpectomy. If chemotherapy is recommended, you will receive the chemotherapy treatment first, followed by radiation therapy.
Hormone therapy — or more accurately, hormone-blocking therapy — is commonly used to treat ILC when the tumor tests positive for estrogen receptors. Two classes of medications are used in hormone therapy: selective estrogen receptor modulators (SERMs), such as tamoxifen; and aromatase inhibitors, such as anastrozole (Arimidex), letrozole (Femara) or exemestane (Aromasin).
A diagnosis of breast cancer may be one of the most difficult situations you’ll ever face. It can set off a roller coaster of emotions, from shock and fear to anger, anxiety or depression. There’s no “right” way to feel and act when you’re dealing with cancer.
Understanding your illness and the treatment options can help you feel more in control. Seek support from your family and friends, and ask your doctor about community and hospital resources. You may find it helpful to talk to other women with breast cancer.
During your treatment, allow yourself time to rest. Take good care of your body by getting enough sleep, eating a healthy diet, staying as physically active as you’re able and taking time to relax. Try to maintain at least some of your daily routine, including social activities.
Finally, take heart in knowing that breast cancer is increasingly about survivorship. The outlook (prognosis) for early-stage ILC is favorable and has improved over time. Most women with invasive lobular carcinoma survive at least 10 years, and often much longer.