Understanding Stage 0 Breast Cancer

Medically Reviewed by Jennifer Robinson, MD on August 17, 2022
3 min read

So the doctor says you have stage 0 breast cancer, and now you have lots of questions. What does that mean? Is it even really cancer?

The truth is, doctors aren’t entirely sure either. Some experts consider it the earliest stage of breast cancer. Others think of it as a sort of precancer stage.

Cancer is defined as a group of diseases with abnormal cells that divide without control. Those cells can also invade nearby tissues. Stage 0 breast cancer is not invasive, though it could be later. It’s less advanced than stage I cancer.

There are two types of stage 0 breast cancer:

  • Noninvasive Paget’s disease, a rare form of breast cancer in the nipple
  • Ductal carcinoma in situ (DCIS). This is what most people mean when they talk about stage 0 breast cancer. The abnormal cells are still in your milk ducts and haven’t affected the fatty tissue that makes up most of your breast. There’s no known cause, and most people don’t have any symptoms, though you may notice a lump or bloody discharge from your nipple. The abnormal cells may or may not become invasive and start to spread. There’s no way to predict if this will happen.

If you’re diagnosed with DCIS, your pathology report will come with a grade. Nuclear grade 3 is the most likely to spread; nuclear grade 1 is the least likely. You should also have a test to see if your cancer cells have estrogen receptors. (Your doctor might call this ER-positive or ER+.) If they do, it's a sign that your cancer might progress more slowly.

Meanwhile, your doctor may suggest that you get genetic testing. It can find changes in your genes that may boost your breast cancer risk.

What happens next depends on all of these factors, as well as your personal choice. Most experts agree that you should get some type of treatment. Even though stage 0 cancer is noninvasive, that could change. Most doctors would say it’s better to be safe than sorry.

There are three main treatment options:

  • Lumpectomy, a surgery that removes the abnormal cells and a little of the normal tissue near them
  • Lumpectomy and radiation
  • Mastectomy, a surgery that removes the entire breast

Some experts believe “watchful waiting” is another valid option. About one third of the women with DCIS will likely get invasive cancer.  Your doctor might suggest that you skip immediate treatment and keep a close eye on your condition instead.

It’s controversial. If you have surgery (and maybe radiation) right away, you might protect yourself from ever getting invasive cancer. On the other hand, you could end up going through painful procedures for no good reason.

But if you skip surgery and radiation at first and choose to get more frequent screening tests, there's a chance you'll end up with cancer that's more advanced (and harder to treat) by the time doctors find it. It's a choice only you and your doctor can make.