New Report Details Rising Incidence of Invasive Lobular Carcinoma

A report from the American Cancer Society reveals that invasive lobular carcinoma (ILC) accounts for 10.6% of all breast cancer (BC) subtypes, highlighting the critical need for increased research and clinical trials to identify risk factors and facilitate treatment efficacy for patients.

What Is Invasive Lobular Carcinoma?

BC is the most common cancer in women, accounting for 30% of all new diagnoses in the population each year. In 2025 alone, statistics project an estimated total of 317,000 new cases of BC in women. Although screening, early intervention, and advanced therapies lead to more promising outcomes for patients, some are diagnosed with more aggressive subtypes.^1,2

ILC originates in the milk-producing lobules of the breast and is the second most common histological subtype of BC. The disease is characterized by a loss of E-cadherin protein adhesion, which causes cancer cells to grow in a linear or dispersed pattern rather than forming a distinct mass. This growth pattern makes ILC more difficult to detect on mammography and can lead to atypical clinical presentations.^1,2

ILC also differs from other BC types in its metastatic behavior, with a greater likelihood of spreading to the gastrointestinal and urinary tract linings and the ovaries. Despite these unique features, ILC is often grouped with the more common invasive ductal carcinoma in research and clinical trials, masking important distinctions in tumor biology, appearance, and treatment response.^1,2

Although ILC generally carries a favorable prognosis, it tends to respond less effectively to neoadjuvant chemotherapy and is associated with an increased risk of bilateral disease, late recurrence, and subsequent primary contralateral cancer.^1,2

“Although lobular [BC] accounts for a little over 10% of all breast cancers, the sheer number of new diagnoses each year makes this disease important to understand,” Angela Giaquinto, MSPH, associate scientist, cancer surveillance research, at the American Cancer Society, and lead author of the report, said in an official statement. “Also, survival rates beyond 7 years are significantly lower for ILC than the most common type of [BC], highlighting the pressing need for prevention and early detection strategies targeting this subtype to be brought to the forefront.”²

What Did the Report Find?

Using data from the nationally representative cancer registry data from the National Cancer Institute and the CDC, researchers found an ILC incidence of 14 per 100,000 women in 2021, accounting for 10.6% of all BC diagnoses. These rates increased over almost 10 years across all racial and ethnic groups. Rates were highest among White women, with an overall incidence of 14.7 per 100,000, followed by Black women at 11 per 100,000. In American Indian/Alaska Native populations, incidence increased to 2.5% annually; however, women under age 50 in this population did have the second-highest rates. The rate increased 4.4% annually among Asian American/Pacific Islander women.^1,2

The researchers also reported survival outcomes, noting that women with ILC have slightly higher survival rates than those with ductal breast cancer during the first 7 years after diagnosis. However, at 10 years, survival was lower for regional (78.2% vs. 76.4%) and distant-stage disease (19.6% vs 12.1%).^1,2

“Invasive lobular [BC] is very understudied, probably because of a very good short-term prognosis. But at 10 years, these women with metastatic disease are half as likely to be alive as their counterparts with ductal cancer, probably because of the unique spread and resistance to therapy,” Rebecca Siegel, MPH, senior scientific director, cancer surveillance research, at the American Cancer Society and senior author of the study, said in a statement. “Our study underscores the need for much more information on lobular cancers across the board, from genetic studies to clinical trial data, so we can improve outcomes for the increasing number of women affected with this cancer.”²

REFERENCES

1. Giaquinto AN, Freedman RA, Newman L, Jemal A, Siegel RL. Lobular breast cancer statistics, 2025. Cancer. Published online October 7, 2025. doi:10.1002/cncr.70061

2. Special ACS report: lesser-known lobular breast cancer on the rise in U.S. women. News release. American Cancer Society. October 7, 2025. Accessed October 10, 2025. https://pressroom.cancer.org/lobular-breast-cancer