Lobular breast cancer originates in the milk-producing glands of the breast, known as lobules. It is the second most common form of invasive breast cancer, following invasive ductal carcinoma. This type of cancer accounts for approximately 10-15% of all invasive breast cancer diagnoses.
Unique Characteristics and Symptoms
Invasive Lobular Carcinoma (ILC) is defined by a unique growth pattern where cancer cells spread in single-file lines through breast tissue. This diffuse growth is different from many other breast cancers that form a solid mass or lump. Because of this linear infiltration, the cancer can be more challenging to detect through physical self-exams.
The symptoms of lobular breast cancer are a direct result of its unusual growth. Instead of a hard lump, individuals may notice an area of thickening or hardening in the breast. Other common signs include swelling or a sense of fullness in one area, changes in skin texture like dimpling or puckering, or a nipple that has recently become inverted. A change in the overall size or shape of the breast can also be an indicator of ILC.
ILC must be distinguished from Lobular Carcinoma in Situ (LCIS). LCIS involves abnormal cells found within the lobules that have not spread into the surrounding breast tissue. While LCIS is not itself cancer, its presence indicates an increased risk for developing invasive breast cancer in the future. ILC, on the other hand, is a true cancer where the cells have already invaded the tissue beyond the lobules.
Diagnostic Process
The diffuse nature of lobular breast cancer presents unique challenges for diagnosis. Standard mammograms, a primary screening tool, are less likely to detect ILC compared to other breast cancers because it rarely forms a solid, easily visible mass. The single-file growth pattern can be difficult to distinguish from normal breast tissue on a mammogram, sometimes leading to delayed detection.
To overcome the limitations of mammography, healthcare providers rely on more sensitive imaging technologies. A breast MRI or an ultrasound can be more effective at identifying the subtle changes associated with ILC. These imaging tests can help pinpoint suspicious areas of thickening or distortion within the breast tissue that might be missed by a mammogram alone.
A biopsy is the definitive method for diagnosing lobular breast cancer. During this procedure, a small sample of the suspicious breast tissue is removed and sent to a laboratory for microscopic analysis. A pathologist examines the cells to confirm the presence of cancer, identify its specific type, and understand its characteristics, such as hormone receptor status.
Specific Treatment Protocols
Treatment for invasive lobular carcinoma is tailored to the individual and often involves a combination of approaches. Surgery is a common first step, with options including a lumpectomy or a mastectomy. A lumpectomy removes the cancerous tissue along with a small margin of healthy tissue, while a mastectomy involves the removal of the entire breast. Achieving clear surgical margins is an important goal.
Following a lumpectomy, radiation therapy is frequently recommended to destroy any remaining cancer cells in the breast and reduce the risk of recurrence. This therapy uses high-energy rays to target the specific area where the cancer was located. The decision to use radiation depends on factors like the size of the tumor and whether lymph nodes were involved.
Systemic therapies that travel through the bloodstream are also a primary component of treatment. Over 80% of lobular cancers are hormone receptor-positive (HR+), meaning they use hormones like estrogen to grow. For these cancers, hormone therapy is a highly effective treatment used to block the effects of hormones or lower their levels in the body. In certain situations, such as when the cancer is more aggressive or has spread, chemotherapy or targeted therapies may also be used.
Prognosis and Associated Risk Factors
The prognosis for invasive lobular carcinoma is generally comparable to that of other common types of breast cancer, as outcomes are more closely tied to the cancer’s stage, grade, and hormone receptor status than to its lobular type. The five-year survival rate for women diagnosed with ILC from stage I to stage III is high, and many remain cancer-free ten years after diagnosis.
Several factors can increase the risk of developing lobular breast cancer. The risk increases with age, with most diagnoses occurring in women over 55. A personal or family history of breast cancer is another significant risk factor. Having a prior diagnosis of Lobular Carcinoma in Situ (LCIS) also elevates a person’s risk.
A rare risk factor is an inherited genetic mutation in the CDH1 gene. This gene provides instructions for making a protein that helps cells stick together. A mutation in the CDH1 gene significantly increases the lifetime risk of developing both invasive lobular breast cancer and a specific type of hereditary diffuse gastric cancer.