How Fast Does Breast Cancer Grow?

Medically Reviewed by Melinda Ratini, MS, DO on March 07, 2024
Written by Kendall K. Morgan
5 min read

If you or someone you know has breast cancer, you may wonder how fast the cancer is growing. You might also wonder how fast it will continue to grow.

Doctors don’t have a way to know when your cancer first started, which means they can’t know how long it took to get to the size it is now. It could have been weeks, months, or longer.

Typically doctors will remove breast cancer tumors as completely as possible. So, they can’t usually track how quickly it grows past that point either.

Studies show that even though breast cancer happens more often now than it did in the past, it doesn’t grow any faster than it did decades ago. On average, breast cancers double in size every 180 days, or about every 6 months. Still, the rate of growth for any specific cancer will depend on many factors. Every person and every cancer is different. Doctors refer to breast cancers that are more likely to grow quickly as more aggressive than those that tend to grow slower.

Factors affecting breast cancer growth

Even though no one can say how fast a certain breast cancer will grow, doctors can tell if a tumor might grow and spread quickly or slowly depending on several known factors explained below. These expectations for how a cancer will act help you and your doctors decide how quickly and aggressively to treat it.

Breast cancer growth depends on the following factors:

  • Subtype. Breast cancers are sorted into several subtypes. Some subtypes grow faster than others. For example, triple-negative breast cancers grow faster than those that are positive for hormone receptors. Your doctor will test a sample of your tumor to see what type it is and how fast it might grow.
  • Stage. Doctors give breast cancer a stage based on whether it’s still in the milk ducts or lobules or has grown out into breast tissue, lymph nodes, or beyond. Breast cancer stages go from 0 to IV. Stage IV means it has spread from the breast to distant parts of the body, such as the brain or other organs. Cancers that have broken through ducts or lobules into breast tissue or spread are more likely to keep growing and spreading faster than those that are still limited to the place where they started.
  • Grade. Your doctors also may give your cancer another number from 1 to 3 for its grade. The grade is based on how normal your cancer cells look under a microscope. Cells that appear more normal are usually less aggressive or less likely to grow quickly. Very abnormal-looking cancer cells are more likely to grow faster and spread.
  • Your age. Most breast cancers happen in women aged 50 or older. But when breast cancer happens at a younger age, it’s more likely to be aggressive and fast-growing.
  • Genetics. Because cancer cells replicate faster than normal cells, they tend to pick up random changes in their genes faster than a normal cell does, too. Some of these changes could make the cells grow more quickly. Some people also are born with certain changes in all of their cells that make cancer both more likely and more likely to grow faster. Changes in genes called BRCA1 and BRCA2 are commonly linked to aggressive breast cancer. Your doctors may recommend genetic testing to check for these changes.

Doctors recognize several different types and subtypes of breast cancers. These include:

  • Ductal carcinoma in situ (DCIS). DCIS breast cancers are in cells that line milk ducts. They haven’t spread from ducts out into breast tissue. This is an early-stage cancer. It’s also called stage 0 breast cancer. DCIS by definition isn’t invasive. But sometimes it can become more aggressive.
  • Hormone receptor (HR)-positive breast cancer. Most breast cancers have receptors for the hormones estrogen and/or progesterone on them. This breast cancer subtype can be invasive, but it tends to grow more slowly than some other breast cancer subtypes. Doctors also can slow HR-positive cancer down with treatments to block your hormones. Because of targeted therapy, people with this type of breast cancer tend to do better than those with other types.
  • HER2-positive breast cancer. About 20% of breast cancers have extra HER2 proteins. This protein makes cancers grow faster. New treatments that work by targeting HER2 have improved the outlook for women with this breast cancer subtype.
  • Triple-negative breast cancer. Triple-negative breast cancers lack both hormone receptors and HER2. This subtype is harder to treat and tends to grow more aggressively. Women with triple-negative breast cancer also have worse outcomes than those with HR-positive or HER2-positive breast cancer.
  • Inflammatory breast cancer. This is a rare cancer type that makes your breast red and swollen; the skin might look pitted like an orange peel. It involves a third or more of the skin of the breast. Inflammatory breast cancer grows much more quickly than other cancer types.
  • Angiosarcoma of the breast. This is another rare type of breast cancer that starts in cells lining blood or lymph vessels. Angiosarcomas often grow and spread quickly.
  • Paget disease of the breast. Paget disease is a rare breast cancer that affects the nipple and the dark circle around the nipple (areola). Usually people with this cancer type have either DCIS or an invasive breast cancer also. The growth will depend on what other features the breast cancer has.

The goal of breast cancer screening is to catch breast cancers early before they get a chance to grow and spread. Most breast cancers caught by routine mammograms are on the smaller side. They also are less likely to have spread.

It’s much easier to get rid of breast cancer -- even if it’s an aggressive type -- when it’s still small and confined to one place. For example, people with triple-negative breast cancers that are caught early have a 5-year relative survival of more than 90%. But because fast-growing tumors are harder to catch at an early stage, people with more aggressive breast cancers also have worse outcomes on average.

The best way to lower your risk of developing a fast-growing, advanced breast cancer is to get regular mammograms. The American Cancer Society recommends women ages 45 to 54 with an average risk of breast cancer get mammograms every year. Women between the ages of 40 and 45 may also choose to have annual screening mammograms. Women may choose to switch to mammograms every other year beginning at age 55 or stick to every year.

If you are at higher risk for breast cancer based on family history, genetics, or other factors, you may want to start having mammograms sooner. Your doctor can help you come up with the right schedule for you depending on your personal risk factors.