If you’ve recently been screened for breast cancer, you may have seen the term atypical ductal hyperplasia (ADH) in your results.

The ducts in your breast are lined with two layers of cells. Ductal hyperplasia refers to having more than two layers of cells. With usual ductal hyperplasia, these extra cells look normal. When they look unusual, it’s called ADH.

A diagnosis of ADH doesn’t mean that you have breast cancer. However, these unusual cells are more likely to turn into cancer. This means that you have a higher risk of developing breast cancer.

According to the American Cancer Society, women with ADH are four to five times more likely to develop breast cancer as women without it. But they also note that most women with ADH don’t develop breast cancer. Still, having ADH means you need to regularly follow up with your doctor for breast cancer screenings.

Ductal carcinoma in situ (DCIS) is another term that’s often used during breast cancer screening. It means that there are cancer cells in your duct, but they haven’t spread to any surrounding tissue. It’s sometimes referred to as stage 0 breast cancer or precancer because it’s the earliest form of breast cancer. You can also think of DCIS as a step above ADH in terms of cancer risk.

DCIS requires treatment, since there’s no way of knowing if it’ll turn into invasive breast cancer. Treatment usually involves removing the cancerous cells, either through a lumpectomy or mastectomy. Radiation, hormonal therapy, or both then follow removal to help prevent the cancer cells from returning.

If you’ve received an ADH diagnosis, you have a few options for your next steps. In most cases, your doctor will likely suggest just keeping an eye on the affected breast and coming in for regular screenings to make sure nothing’s changed. Since there’s no way of knowing if or when someone with ADH will develop cancer in the future, make sure you follow your doctor’s recommendations for more frequent screenings.

You can also make lifestyle changes to reduce your risk of developing breast cancer. These include:

  • reducing your alcohol intake
  • avoiding tobacco
  • maintaining a healthy weight through regular exercise and eating a balanced diet
  • using nonhormonal treatment options to manage any symptoms of menopause

Your doctor might suggest medication if you’re at a higher risk of developing breast cancer. A higher risk can be due to previously having cancer or undergoing radiation therapy around your chest at a young age.

The most common types of medication used to lower breast cancer risk are selective estrogen-receptor modulators such as tamoxifen, and aromatase inhibitors such as exemestane.

These medications can cause serious side effects. Your doctor will only recommend them if you have a substantially higher risk of developing breast cancer.

If you follow up with regular screenings, any signs of breast cancer will likely be caught before they start causing symptoms. However, because breast cancer can affect each woman differently, it’s important to keep an eye out for certain warning signs.

These include:

  • a lump, knot, or thicker skin on part of your breast or under your arm
  • swelling, heat, redness, or darkness in part of your breast
  • a change in the size or shape of your breast
  • sudden nipple discharge that isn’t breast milk
  • pain in your breast that won’t go away
  • dimples in the skin of your breast
  • itchy, scaly, or painful rash on your nipple
  • your nipple turning inward

Check for these signs every time you do a breast self-exam. Tell your doctor as soon as possible if you notice any of these warning signs.

Receiving an ADH diagnosis doesn’t mean you have breast cancer, but it does put you at a higher risk of developing breast cancer. Make sure you follow up with your doctor for regular screenings and tell them about any new symptoms you have.

In the meantime, try to avoid things that increase your risk of developing cancer, such as alcohol and tobacco. Eating a healthy diet and getting regular exercise can also help reduce your risk.