Rising Rates of Invasive Lobular Carcinoma in the U.S.
Invasive lobular carcinoma (ILC), a specific type of breast cancer, has been increasing in the United States at a rate more than three times faster than all other breast cancers combined over the last decade, according to a recent study.
This type of cancer, which can be tricky to detect during regular mammograms, is responsible for more than 10% of breast cancer cases across the country.
The analysis, published in the journal Cancer, examined national data from 2012 to 2021 and found that ILC rates rose by about 2.8% annually, while other breast cancers increased by approximately 0.8% each year.
I spoke with Dr. Leana Wen, an emergency physician and wellness expert, to clarify several aspects regarding ILC, including its commonality, diagnosis difficulties, the most vulnerable populations, treatment options, and preventive measures.
What is Invasive Lobular Carcinoma?
Dr. Wen explained that invasive lobular carcinoma arises in the milk-producing lobules of the breast and can spread to nearby tissues. Typically, these tumors are hormone receptor-positive, which means their growth is stimulated by hormones like estrogen or progesterone.
It’s the second most prevalent breast cancer type after invasive ductal carcinoma, representing about 10% to 15% of new breast cancer cases. Annually, around 47,500 ILC diagnoses occur in the U.S., affecting more women than cancers of the brain, kidneys, liver, pancreas, or ovaries.
Challenges in Detection
One reason ILC is often harder to detect in routine screenings is that it doesn’t typically alter breast structure as drastically as other types of cancer. Instead of forming a distinct mass, the cancer spreads in thin strands resembling normal tissue, which can make mammograms show only minor changes or none at all. This can lead to women feeling less likely to notice a lump during self-examinations, potentially delaying diagnosis.
Imaging Techniques for Diagnosis
To diagnose ILC, breast ultrasounds can highlight thickened areas not visible on a mammogram, and MRIs can provide detailed views that uncover cancers hidden in denser breast tissue. These diagnostics aren’t universally recommended; mammography remains the standard, but higher-risk women—those with dense breasts or a strong family history—may require additional imaging.
Trends in Diagnosis and Risk Factors
The study revealed that ILC cases are increasing across all racial and ethnic groups, with the most significant rise among Asian American and Pacific Islander women, whose rates have seen an increase of about 4.4% annually. Women aged 65 and older are also diagnosed with ILC more frequently compared to invasive ductal carcinoma, with about 70% of new cases diagnosed in women over 60, and the median age being 66.
Reasons for Increased Incidence
There are several possible explanations for the rise in ILC cases. Hormone exposure changes could be a factor, along with increasing rates of obesity and alcohol use. Additionally, shifts in childbearing patterns and menopause could play a role. Improvements in diagnosis and greater awareness of ILC might lead to better identification, as some cases may have previously been misclassified as ductal cancers. Moreover, as more women live longer post-menopause, this may increase their likelihood of developing ILC as opposed to other breast cancer types.
Treatment Options for ILC
Treatment for ILC typically mirrors that of other breast cancers, involving surgery to remove the tumor, followed by potential radiation and hormonal therapy, given most tumors respond to estrogen or progesterone. Chemotherapy may be considered in some situations. For advanced cases, newer targeted medications paired with hormonal treatment can be beneficial. However, ILC may resist treatment more than other types, particularly in its advanced stages, often resulting in a poorer prognosis once it spreads.
Reducing Risk of ILC and Other Breast Cancers
While some risk factors, like age and family history, are unavoidable, lifestyle choices can significantly impact risk. Quitting smoking, limiting alcohol, maintaining a healthy weight, and being physically active can help decrease the likelihood of breast cancer. A nutritious diet rich in fruits, vegetables, and whole grains might also support overall health and reduce inflammation associated with cancer.
Regular screenings and understanding what’s normal for one’s body are essential for early detection. It’s wise to discuss personal risk factors with a healthcare provider to determine when to start screening and whether additional tests besides mammograms are necessary. Lastly, women should be vigilant about any changes in their breasts—like thickening, swelling, discharge, or new areas of fullness—and seek medical advice promptly if they notice anything unusual.
