Rates of once-rare breast cancer have doubled since 70s

A hard-to-detect form of breast cancer now makes up about 1 in 10 cases in the U.S., a recent American Cancer Society report found.

“Although lobular breast cancer 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, associate scientist of cancer surveillance research at the American Cancer Society and lead author of the report, said in an Oct. 7 society news release. “Also, survival rates beyond seven years are significantly lower for ILC than the most common type of breast cancer, highlighting the pressing need for prevention and early detection strategies targeting this subtype to be brought to the forefront.”

Here is what to know:

1. Invasive lobular carcinoma is the second most common breast cancer type and saw incident rates increase by 2.8% each year from 2012 to 2021. For comparison, the increase in incidence rates for all other breast cancers combined was 0.8% in the same time period.

2. Rates of invasive lobular carcinoma, which develops in the milk-producing glands of the breast, has doubled since the 1970s.

3. The cancer is most common in white women, who comprise about 33% to 55% more cases than other racial and ethnic groups. However, the fastest rise in cases is among Asian American and Pacific Islander women, who have seen a 4.4% yearly increase.

4. Lobular breast cancer is more difficult to detect on mammograms because it tends to grow in a straight line or sheet-like pattern, Anita Mamtani, MD, a surgical oncologist specializing in breast cancer at Memorial Sloan Kettering Cancer Center, told ABC News. 

5. Despite rising rates, lobular breast cancer has not drawn a lot of attention because its five-year survival rate is over 90%. However, survival often drops after that point. It is less responsive to some treatments, more likely to occur in both breasts and may have poorer long-term outcomes.