Invasive Lobular Carcinoma (ILC) Breast Cancer

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Invasive Lobular Carcinoma (ILC) is a type of breast cancer that starts in the lobules of your breast, where milk is produced. At first, the cancer cells are at work in the lining of the milk lobes, but later these cells invade or infiltrate the nearby tissue outside of the lobes. As with invasive ductal carcinoma (IDC), ILC has the potential to spread, or metastasize, to other parts of your body.

ILC Is Less Common, Harder to Image

ILC is diagnosed in only one out of every 10 invasive breast cancers. In dense breast tissue, with lobes located near the chest wall, ILC may be more difficult to detect with a mammogram than other types of breast cancer.

Also Known As:

Infiltrating Lobular Carcinoma, ILC

Signs and Symptoms

ILC does not always feel like a breast lump. ILC cells may leave your lobes through one opening, staying together in a line. They can proceed to infiltrate fatty tissue, creating a web-like mass. This web of cancer cells may feel like a thickened area of breast tissue, and at first, may not cause concern or pain. Unfortunately, if left undetected, ILC can develop into a mass that is about 3/4 inch (2 centimeters) to about 2 inches (5 centimeters) or bigger in size, before causing more noticeable symptoms.

When to Seek Medical Help

If you have any of these symptoms, get them checked out by a health professional right away:

  • A thickened area within your breast
  • An area that feels "full" or swells (not due to lactation or hormonal cycle)
  • Breast skin changes such as dimpling, thickening, or different texture
  • Nipple drawing in (retracting)

Diagnosis of ILC

Because ILC can easily hide within breast tissue, a mammogram won't always catch it, particularly in the earliest stages. If it does show up on a mammogram, it will be unclear as to its actual nature. Your doctor may send you for a breast ultrasound, which is better at detecting ILC than a mammogram. To get the best overall image of cancer, you may need a breast MRI, so your surgeon will be able to see the size and location of the mass. Finally, to get a clear diagnosis of ILC, a breast biopsy must be done, so that a sample of the tissue can be examined by a pathologist.

Stages of ILC

ILC can be diagnosed from stages 1 through 4. It is more likely than IDC to occur in both breasts — about 20% of patients diagnosed with ILC will have bilateral breast cancer. A breast MRI will help reveal this, and treatment can be tailored to combat both cancerous masses at once.

Treatments for ILC

Your doctor will review the characteristics of your cancer and will recommend a treatment plan to get rid of the cancer cells and to prevent recurrence. Treatments may include:

  • Lumpectomy (for a tumor that is small enough to remove, with some margin of surrounding tissue)
  • Mastectomy (if the tumor has invaded much of your breast, or is large in comparison to your breast)
  • Chemotherapy
  • Radiation
  • Hormone Therapy (for estrogen-receptor positive breast cancer)
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