Breast cancer rates have risen by 1% annually over the past decade, with the sharpest increase in women under 50, according to a new report released by the American Cancer Society.

But breast cancer deaths have declined by 44% since 1989, preventing about 517,900 deaths, according to the report. This is largely because of improvements in treatment and earlier screening.

The American Cancer Society released its biennial update on breast cancer trends Tuesday, marking the start of Breast Cancer Awareness Month.

“The encouraging news is breast cancer mortality rates continue to decrease, thanks to advances in early detection and treatment,” said Angela Giaquinto, associate scientist for cancer surveillance research at the American Cancer Society and lead author of the study. “But future progress may be thwarted by increasing incidence, especially among younger women, and consequences of the COVID-19 pandemic, such as delayed diagnosis due to interruptions in screening.”

Massachusetts ranks 19th among U.S. states for breast cancer mortality and 22nd for incidences, about in line with national averages.

In the Bay State, about 136 out of every 100,000 people were diagnosed with breast cancer from 2017 to 2021, and about 16 people out of 100,000 died from breast cancer around that same period, according to the latest data.

“The data released today contributes to a growing body of evidence that the rates of breast cancer in young women are increasing, said  Dr. Ann Partridge, MD founder and director of the program for young adults with breast cancer at Dana-Farber Cancer Institute.

“This trend is very concerning as breast cancer is the number one cause of cancer mortality in women under 40, where women are generally not being screened and the disease they develop is more aggressive and more difficult to treat,” she said.

Though women under 50 have a low overall risk, breast cancer has become increasingly prevalent in younger women.

“There is a slightly higher increase in the rate of breast cancer diagnosis for women who are under age 50 versus those that are above age 50,” said Karen Knudsen, chief executive officer of the American Cancer Society. “These are things we are watching to try to understand.”

Researchers also are trying to understand the racial disparities in breast cancer diagnosis and mortality. Black women have a lower survival rate for breast cancer than white women, no matter the stage of the disease.

“Women today are a lot less likely to die from breast cancer, but alarming disparities still remain, especially for Asian American, Pacific Islander, Native American and Black women,” Dr. William Dahut, chief scientific officer at ACS, said in Tuesday’s release.

Recent research has found that several types of cancer are showing up in young people at surprising rates. In January, a study released by ACS researchers found an alarming number of colorectal cancer cases in young adults.

Dahut said in January that better screening could have some role in more cancers being diagnosed, but he said other factors, especially rising obesity rates, are likely driving the rise in cancer.