Rising Incidence of Lobular Breast Cancer in U.S. Women: What You Need to Know

Lobular breast cancer, a less common form of breast cancer originating in the milk-producing lobules, is experiencing a notable increase among women in the United States. Recently published by the American Cancer Society, a new report highlights that approximately 33,600 women are expected to be diagnosed with invasive lobular carcinoma (ILC) this year alone. Although lobular breast cancer accounts for just over 10% of all breast cancers, its rising incidence emphasizes the importance of awareness and tailored treatment approaches.

The report also ranks lobular breast cancer as the seventh most common cancer among women nationally. From 2012 to 2021, incidence rates for ILC surged by about 2.8% annually, a steeper increase compared to the 0.8% annual growth observed in all other breast cancers combined. Notably, the incidence is highest among White women, with rates around 14.7 per 100,000 women, followed by Black women at approximately 11 per 100,000. Asian American and Pacific Islander women experienced the fastest rise in diagnoses, with a yearly increase of 4.4%.

ILC presents unique challenges in detection because its tumors tend to grow in a linear or dispersed pattern, rather than forming distinct lumps like other breast cancers. This growth pattern can delay diagnosis, complicate treatment, and lead to poorer long-term outcomes, especially in advanced stages. Unlike invasive ductal carcinoma, which is more easily palpable, ILC might go unnoticed for longer periods, further emphasizing the need for effective screening techniques.

Survival rates in the initial years after diagnosis are slightly better for ILC than for ductal breast cancers, especially for localized disease. However, when cancer spreads regionally or metastasizes to distant sites, the survival rate drops significantly, with only about 12.1% of women with metastatic ILC surviving at ten years. Researchers stress that despite good short-term prognoses, metastatic lobular cancer remains a serious concern due to its tendency to resist therapy and spread in an atypical manner.

The study analyzed data from the North American Association of Central Cancer Registries and the SEER program, revealing disparities by race and ethnicity. The incidence among Asian American/Pacific Islander women increased the fastest, and White women continue to have the highest rates. The report underscores the critical need for more research into the genetics, early detection, and treatment of lobular breast cancer to improve survival outcomes.

Experts emphasize that lobular breast cancer is understudied because of its relatively good short-term prognosis. Nevertheless, long-term survival for women with metastatic disease is considerably lower, calling for increased focus on prevention, early detection strategies, and personalized therapies that address its unique characteristics.