A lesser-known type of breast cancer is on the rise among women in the U.S.—highlighting the need for us to pay closer attention to it.

An estimated 33,600 women will be diagnosed with lobular breast cancer or invasive lobular carcinoma (ILC) this year, according to new projections by the American Cancer Society (ACS). 

The report finds that incidence rates of ILC—which starts in the milk-producing glands of the breast—have increased more steeply (2.8 percent per year) than all other breast cancers combined (0.8 percent) from 2012 to 2021.

“Although lobular breast cancer accounts for a little over 10 percent of all breast cancers, the sheer number of new diagnoses each year makes this disease important to understand,” said report author Angela Giaquinto, associate scientist at ACS, in a statement. 

“Also, survival rates beyond seven years are significantly lower for ILC than the most common type of breast cancer [invasive ductal carcinoma (IDC)], highlighting the pressing need for prevention and early detection strategies targeting this subtype to be brought to the forefront.”

The authors emphasize this is needed to improve the chance of better patient outcomes.

In research and clinical trials, ILC is typically combined with the more common IDC, which can conceal many of its own key unique appearance and growth characteristics, according to the study authors.

“ILC has distinctive characteristics that can contribute to delayed detection, resistance to therapy, and poorer prognosis for advanced disease,” the study authors wrote in the paper.

“Differentiating ILC from ductal carcinoma in research and clinical trials could help identify risk factors, facilitate treatment efficacy and lead to better understanding of metastatic mechanisms, thus improving outcomes for the increasing number of affected women.”

Reflecting a trend seen in other breast cancers, the U.S. report also found the steepest rise in ILC incidence among women of Asian American and Pacific Islander descent, increasing 4.4 percent per year from 2012 to 2021.

Overall, White women have the highest incidence rate of ILC and Black women have the second highest. 

While survival for women with ILC is slightly higher than it is for ductal breast cancer in the first seven years after diagnosis and for localized-stage disease, it is lower for both regional and distant-stage disease at 10 years after diagnosis. 

“Invasive lobular breast cancer 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,” said author Rebecca Siegel, senior scientific director at ACS, 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.”

Newsweek has reached out to the researchers for additional comment. 

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Giaquinto, A. N., Freedman, R. A., Newman, L. A., Jemal, A., & Siegel, R. L. (2025). Lobular breast cancer statistics, 2025. Cancer, 131(20). https://doi.org/10.1002/cncr.70061