What is Invasive Lobular Carcinoma (ILC)?
Invasive Lobular Carcinoma (ILC) is a less common but increasingly visible form of breast cancer that begins in the lobules, the milk-producing glands. Unlike the more familiar invasive ductal carcinoma (IDC), ILC tends to grow more diffusely and may not form a well-defined lump. This subtle growth pattern can delay detection and complicate early diagnosis.
The US Trends: Why ILC is Rising
Recent data from the American Cancer Society indicate that approximately 33,600 women in the United States are expected to be diagnosed with ILC this year. ILC has been climbing at about 2.8% per year from 2012 to 2021—faster than the roughly 0.8% annual rise seen in other breast cancers. While ILC represents just over 10% of breast cancer cases, its slower-to-detect nature means outcomes can lag behind other subtypes, particularly in advanced disease.
What might be driving the rise?
- Screening and detection: Traditional mammograms can miss the diffuse spread of ILC, leading to later diagnoses. Advances in imaging, such as MRI and tomosynthesis, are helping to identify more cases, which may partly account for rising incidence.
- Hormonal influences: Many ILC tumors are hormone receptor–positive, suggesting a role for prolonged estrogen exposure.
- <strongAging population and therapies: More women live longer and more use menopausal hormone therapies, potentially increasing risk for hormone-sensitive cancers like ILC.
- Genetic and molecular factors: Variants linked to lobular cancer risk (for example, CDH1) may contribute to susceptibility in some individuals.
- Lifestyle and environment: Obesity, alcohol use, and reproductive choices can influence overall breast cancer risk, including ILC.
Recognizing the Red Flags: Early Signs to Watch For
ILC often lacks a discrete lump. Awareness of subtler changes can prompt earlier evaluation and treatment, which improves outcomes. Consider talking to a clinician if you notice any of the following persistent changes:
- Breast thickening or fullness: A region that feels unusually denser or firmer than surrounding tissue.
- Changes in shape or size: Slight asymmetry, swelling, or distortion without pain.
- Skin changes: Dimples, puckering, or an “orange peel” texture of the skin.
- Nipple changes: Retraction or inversion, or new nipple discharge (even if not bloody).
- Pain or discomfort: A persistent ache not typical for other breast conditions.
- Lymph node changes: Swelling in the underarm or near the collarbone could suggest spread.
Note that not all breast cancers present with a lump, and some ILCs are diagnosed through imaging or biopsy after subtle signs are detected. If you notice any persistent changes, seek medical advice promptly.
Who Is at Greater Risk?
While most breast cancers occur in older women, ILC risk is influenced by a mix of factors that often overlap with general breast cancer risks. Key considerations include:
- Female sex and increasing age
- Hormonal and reproductive history (early menstruation, late menopause, fewer pregnancies, late first birth)
- Hormone replacement therapy use
- Genetic predisposition (CDH1 mutations; BRCA1/2 may also play a role)
- Family history of breast cancer
- Breast density
- Lifestyle factors such as obesity, alcohol, and physical inactivity
What You Can Do
Because early detection remains a cornerstone of improving outcomes for ILC, it’s important to stay informed and proactive. Regular screening according to your healthcare provider’s guidance, awareness of subtle breast changes, and open conversations about hormone therapy and family history can help. If you notice any persistent alteration in breast tissue, don’t delay a professional evaluation. Early detection is often the most effective path to successful treatment.
Beyond ILC: Context in the Breast Cancer Landscape
Breast cancer remains the most commonly diagnosed cancer among women worldwide, with substantial mortality in many regions. While ILC is a rising subtype in the US, ongoing efforts in screening, research, and personalized care are essential to addressing both common and less typical presentations of breast cancer.
