Diagnosing invasive lobular carcinoma usually involves a combination of procedures, including a physical examination and imaging tests. ILC tends to be multifocal, meaning that there is more than one area of cancer within the breast. Some studies have shown that ILC is also more likely to affect both breasts (called bilateral cancer) than other types of invasive breast cancer.
Procedures for diagnosing ILC can include:
- Physical examination of the breasts: Your doctor may be able to feel a thickening or hardening in the breast during a physical examination. With invasive lobular carcinoma, this is a more common finding than a distinct lump. He or she also will feel the lymph nodes under the armpit and above the collarbone to see if there is any swelling or other unusual changes.
- Mammography: Invasive lobular carcinoma may be found by mammography, a test that obtains X-ray images of the breast. Mammograms are used to screen apparently healthy women for early signs of breast cancer. However, ILC does not always show up well on a mammogram because of the cells’ tendency to grow in a single-file line, rather than form a mass. If mammogram does find invasive lobular carcinoma, the tumor may appear smaller than it actually is. Whenever a screening mammogram highlights an area of concern, additional mammograms often will be done to gather more information about that area. Mammography will be performed on both breasts.
- Ultrasound bounces sound waves off of the breast to create additional images of the tissue. Ultrasound can be used in addition to mammography. Ultrasound appears to be more accurate in detecting invasive lobular carcinoma than mammography is. As with mammography, however, the tumor may appear smaller than it actually is.
- Breast MRI: MRI, or magnetic resonance imaging, uses magnetic fields, radio waves, and a computer to obtain images of tissues inside the body. In selected cases, a doctor may use breast MRI to gather more information about a suspicious area within the breast.
Biopsy: If you do have a suspicious mammogram or other imaging test result, your doctor will probably want you to have a biopsy. A biopsy involves taking out some or all of the abnormal-looking tissue for examination by a pathologist (a doctor trained to diagnose cancer from biopsy samples) under a microscope.
When possible, a doctor will usually use one of the quicker, less invasive approaches to biopsy. These include the following tests:
- Fine needle aspiration biopsy: A very small, hollow needle is inserted into the breast. A sample of cells is removed and examined under the microscope. This method leaves no scars.
- Core needle biopsy: A larger needle is inserted to remove several cylinder-shaped samples of tissue from the area that looks suspicious. In order to get the core needle through the skin, the surgeon must make a tiny incision. This leaves a very tiny scar that is barely visible after a few weeks.
If a needle biopsy is not able to remove cells or tissue, or it does not give definite results (inconclusive), a more involved biopsy may be necessary. These biopsies are more like regular surgery than needle biopsies:
- Incisional biopsy: Incisional biopsy removes a small piece of tissue for examination.
- Excisional biopsy: Excisional biopsy attempts to remove the entire suspicious lump of tissue from the breast.
For more information on these tests, visit the Breast Cancer Tests: Screening, Diagnosis, and Monitoring section.
The tissue samples are sent to a pathologist for examination under a microscope. The pathologist looks for the cell appearance and growth patterns that are typical of invasive lobular carcinoma. He or she may also order a special test called an E-cadherin protein study. E-cadherin, or CDH1, is a gene that controls the activity of a protein that keeps cancer cells from spreading into normal, healthy tissue. A mutation, or unusual change, in the CDH1 gene can cause this gene to “turn off.” Some researchers feel that turning off CDH1 might cause ILC to develop.
Testing invasive lobular carcinoma cells for this mutation can help distinguish it from LCIS (lobular carcinoma in situ), a group of abnormal cells in the lobule that are not cancer. Rather, LCIS is considered to be an indication that someone is at increased risk of developing breast cancer. Most invasive lobular carcinomas do have some areas of LCIS within them.
The surgical biopsies are done only to make the diagnosis. If invasive lobular carcinoma is diagnosed, more surgery is needed to ensure all of the cancer is removed along with “clear margins,” which means that a border of healthy tissue around the cancer is also removed. Usually this means having lumpectomy or, in some cases, mastectomy.