Breast cancer is no longer diagnosed primarily in older cisgender females and is found more often in those under the age of 40. That said, diagnosis can be hard because routine screening isn’t recommended at this younger age range.

Younger women with breast cancer experience unique challenges.

According to a 2021 clinical review, breast cancer is now the most common type of cancer for women younger than 39.

However, the disease is often diagnosed in its later stages, when it tends to be more aggressive. This means the survival rate is lower and the recurrence rate is higher.

Knowing your risk factors for breast cancer, and its early signs and symptoms, can help you get started on treatment sooner.

Breast cancer has been considered rare in your 20s or 30s. Only 5 percent of all cases have been in this age group.

Female breast cancer is most frequently diagnosed in women ages 65 to 74. The median age at diagnosis is 63.

More recent data also shows that breast cancer is actually the most common type of cancer among young adults ages 15 to 39, accounting for 30 percent of all cancers in this age group, according to a 2021 review.

In addition, data from the 2017 U.S. Surveillance, Epidemiology and End Results (SEER) database showed that 5.6 percent of invasive breast cancer diagnoses were in women under 40.

Here are some additional important statistics to know on breast cancer at a younger age:

  • Nine percent of all new cases of breast cancer in the United States are in women younger than 45.
  • In the United States, 1 in 196 women under age 40 receive a diagnosis of breast cancer. More than 12,000 women younger than 40 were estimated to get a diagnosis of breast cancer in 2020 alone.
  • Women younger than 50 are more likely to get a diagnosis of triple-negative breast cancer (TNBC). TNBC is cancer that tests negative for progesterone and estrogen receptors, as well as too much HER2 protein.
  • The number of metastatic breast cancer cases diagnosed in women ages 25 to 39 has increased by 2.1 percent per year from 1976 to 2009.
  • Survival rates are lower for women younger than 40. According to a 2016 study, women ages 40 or younger were 30 percent more likely to die from breast cancer than women who were diagnosed between the ages of 51 and 60.
  • Almost 1,000 women younger than 40 died from breast cancer in 2019 in the United States.
  • The number of new cases of pregnancy-associated breast cancer (PABC), which is breast cancer diagnosed during or up to a year after pregnancy or breastfeeding, ranges between 17.5 and 39.9 per 100,000 births. However, the likelihood of PABC during pregnancy is lower than after birth.
  • People who have given birth have a higher risk of developing breast cancer than those who have not for as long as 20 years after pregnancy.

According to the National Cancer Institute, if you’re in your 30s, your risk of breast cancer is 1 in 204, or about 0.4 percent.

By age 40, the risk is roughly 1 in 65, or about 1.5 percent.

By age 60, the chance increases to 1 in 28, or 3.5 percent.

Out of all types of cancer, though, breast cancer is the most common among U.S. women. The average U.S. woman’s risk of developing breast cancer during her lifetime is about 12 percent.

Some women are at an increased risk of breast cancer in their 20s or 30s. These risk factors include:

  • having a close family member (mother, sister, or aunt) who was diagnosed with breast cancer before age 50
  • having a close male blood relative with breast cancer
  • having a BRCA1 or BRCA2 gene mutation
  • having received radiation treatment to the chest or breast before age 30
  • hormonal factors, such as the early start of menstruation, use of birth control pills, or anovulatory infertility

Other risk factors that apply to women of any age include:

  • having a high percentage of breast tissue that appears dense on a mammogram
  • having had a previous abnormal breast biopsy
  • having had your first menstrual period before age 12
  • having your first full-term pregnancy after age 30
  • never having a full-term pregnancy
  • being physically inactive or overweight
  • being of Ashkenazi Jewish heritage
  • drinking heavy amounts of alcohol

Breast cancer happens when cells in the breast begin to grow and multiply abnormally. Changes in DNA can cause normal breast cells to become abnormal.

The exact reason why normal cells turn into cancerous cells is unclear, but researchers know that hormones, environmental factors, and genetics each play a role.

Roughly 5 to 10 percent of breast cancers are linked to inherited gene mutations. The most well known are breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2).

If you have a family history of breast or ovarian cancer, your doctor may suggest testing your blood for these specific mutations.

In some cases, breast cancer in your 20s and 30s has been found to differ biologically from the cancers found in older women.

For example, younger women are more likely to receive a diagnosis of triple-negative and HER2-positive breast cancers than older women.

The number of women under 40 receiving diagnoses of metastatic breast cancer is increasing. The progression to metastasis in breast cancer is more likely in adolescent and young women than in older women who have a diagnosis of early stage breast cancer.

Metastatic breast cancer means that the cancer has advanced to stage 4. It has moved beyond the breast tissue into other areas of the body, such as the bones or the brain.

Survival rates are lower for cancer that has metastasized to other parts of the body.

According to the American Cancer Society, the 5-year survival rate for women with breast cancer that has spread to other parts of the body is 28 percent for all ages.

Among every age, adolescent and young women have lower breast cancer survival rates than older women. The more advanced the cancer, the poorer the outlook in this group.

It’s often difficult for doctors to diagnose breast cancer in women under 40, because younger women have denser breasts. A tumor won’t typically show up as well on mammograms in younger women.

However, some signs and symptoms of breast cancer may include:

  • a change or lump in the breast area
  • swelling in your underarm lymph node area
  • changes to your nipples, like redness, scaliness, or discharge that is not breast milk

The majority of young women who receive a diagnosis of breast cancer discover an abnormality themselves.

Always report any breast changes to your doctor. These include:

  • changes in the skin
  • nipple changes and discharge
  • pain
  • tenderness
  • a lump or mass in the breast

You know your body best, so any other unusual change to your breast or underarm area is worth showing your doctor.

Breast cancer can happen in your 20s and 30s. Since routine screening isn’t recommended for this age group, diagnosis can be difficult.

That’s why understanding the statistics, as well as your personal risk factors, can help you with early diagnosis and treatment.