Invasive Lobular Carcinoma

Overview

Invasive lobular carcinoma (ILC) is the second most common type of breast cancer, after invasive ductal carcinoma. It begins in the lobules, the milk-producing glands at the ends of the breast ducts, and grows into the surrounding breast tissue, with the potential to spread to lymph nodes and beyond. The word "invasive" indicates that it has spread beyond where it started.

A distinctive feature of lobular carcinoma is the way its cells often grow in single-file lines that spread through the breast without forming a firm, distinct lump. As a result, it can be harder to feel during a breast exam and harder to see on a standard mammogram, and it may instead cause a vague area of thickening or fullness. Because of this, MRI is sometimes used to assess its extent. Most invasive lobular cancers are sensitive to hormones, which influences treatment. With appropriate care, many people with ILC have good outcomes, especially when it is found early.

Symptoms

Because lobular carcinoma often does not form a clear lump, its signs can be subtle and easy to overlook.

• An area of thickening, fullness, or swelling in part of the breast rather than a distinct lump
• A change in the texture or feel of an area of breast tissue
• A change in the size or shape of the breast
• Skin dimpling, puckering, or other skin changes
• Nipple changes, such as turning inward
• Sometimes a lump, when present

Any new, persistent change in how a breast looks or feels should be checked by a doctor. Because lobular carcinoma can be subtle, it is worth reporting even vague changes rather than waiting.

Causes

As with other breast cancers, lobular carcinoma develops when cells, in this case in the lobules, acquire genetic changes that make them grow uncontrollably. The precise cause in an individual is usually unknown.

• Genetic changes: Changes acquired over a lifetime, and in some people inherited gene changes that raise breast cancer risk.
• Hormonal influences: Lifetime exposure to estrogen affects risk, and combined hormone therapy after menopause has been linked to lobular cancer in particular.
• Aging: Risk rises with age.

A prior diagnosis of lobular carcinoma in situ, a non-invasive change in the lobules, is associated with a higher overall risk of breast cancer, though it is not the same as invasive cancer.

Risk Factors

• Increasing age
• A personal or family history of breast cancer
• Inherited gene changes that raise breast cancer risk
• Use of combined hormone therapy after menopause
• A history of lobular carcinoma in situ
• Earlier first period, later menopause, or later first childbirth

Diagnosis

Diagnosis can be more challenging than for other breast cancers because of the subtle growth pattern, so imaging and a tissue sample are key.

• Mammography: Used for screening and assessment, though lobular cancer can be harder to see.
• Ultrasound and MRI: Help define an abnormal area; MRI is particularly useful for assessing the extent of lobular cancer.
• Biopsy: A tissue sample confirms invasive lobular carcinoma under the microscope.
• Tumor testing: The cancer is tested for hormone receptors and HER2 to guide treatment; most lobular cancers are hormone-receptor positive.
• Staging: Lymph node evaluation and further tests if spread is suspected.

Treatment

Treatment is similar in principle to other invasive breast cancers and is tailored to the stage and tumor features.

• Surgery: Breast-conserving surgery or mastectomy, with assessment of underarm lymph nodes. Because lobular cancer can be more extensive than it appears, the choice of surgery is carefully planned.
• Radiation therapy: Often given after breast-conserving surgery and in some cases after mastectomy.
• Hormone therapy: Very commonly used, since most lobular cancers respond to hormones; these medicines block estrogen's effects to reduce recurrence.
• Chemotherapy: Used in selected cases depending on tumor features and stage.
• Targeted therapy: Used when the tumor has specific features that make it suitable.

A multidisciplinary team helps design a plan based on the individual cancer, the extent of disease, and the person's preferences.

Prevention

Not all breast cancer can be prevented, but several measures lower risk and support early detection.

• Attend recommended breast cancer screening
• Know how your breasts normally look and feel, and report changes, including subtle thickening
• Maintain a healthy weight and stay active
• Limit alcohol
• Discuss the risks and benefits of menopausal hormone therapy with your doctor
• Consider genetic counseling if you have a strong family history

When to See a Doctor

See a doctor if you notice any persistent change in a breast, even if there is no obvious lump. Reasons to seek evaluation include:

• A new area of thickening, fullness, or swelling in the breast
• A change in the size, shape, or texture of a breast
• Skin dimpling or puckering, or nipple changes

Because lobular carcinoma can be subtle, it is important to report vague changes rather than wait. Most breast changes are not cancer, but timely evaluation allows early treatment when needed.

Related Topics

Frequently Asked Questions

References

1. American Cancer Society. Invasive Breast Cancer (IDC/ILC).
2. National Cancer Institute (NCI). Breast Cancer Treatment.
3. Mayo Clinic. Invasive lobular carcinoma — Symptoms and causes.
4. MedlinePlus, U.S. National Library of Medicine. Breast cancer.