How Fast Does Breast Cancer Start, Grow, and Spread?

Breast Cancer Growth Rate and Doubling Time

If you have been diagnosed with or are worried about breast cancer, you may be wondering how fast it develops, grows, and spreads. In other words, when a cancer is found, you may wonder when it started, how fast will it double in size if not removed, and how quickly might it spread to lymph nodes, bones, or other regions of the body. These questions are important for many reasons and can vary depending on the type of breast cancer you have and its molecular characteristics.

The question of how long a breast cancer has been present in the body when it is diagnosed is more difficult to evaluate, but it's likely that many tumors began a minimum of five years before detection. Let's look at the factors that can affect the growth rate of cancer, how long it takes one of these tumors to develop, and why these answers can be important for people living with the disease today.

How Fast Breast Cancer Grows

People may wonder about growth or doubling time when considering how long to wait to begin treatment. This growth is also very important to understand if you have a lump and have been advised to simply observe it over time. (Unless your doctor is extremely confident that a lump is benign, it should be evaluated right away rather than waiting.)

In general, the growth of breast cancer can be quite variable, but several studies provide at least an estimate of what may be happening.

The Biology of Breast Cancer Cell Growth

Cancer begins when a normal breast cell undergoes a number of mutations in genes that control the growth of the cell. These mutations may occur over a long period of time, even decades, before a cancer cell forms, and a cancer cell must divide on average 30 times before it forms a mass that can be felt in the breast. Since tumor cells multiply and divide exponentially—one cell becomes two, two cells become four, and so on—a tumor will increase more rapidly in size the larger it is.

That said, not all cells are dividing at one time, and growth can be different at different stages in the formation of a tumor. Compared with many types of cancer, breast cancer has a "low growth fraction," meaning that the proportion of cancer cells that are in an active cell cycle is low. Some tumors, such as some leukemias and lymphomas, have much higher growth fractions (and may be present for a much shorter period of time before they become apparent, even in children).

Breast Cancer Doubling Time

An easier way to envision how fast a breast cancer grows is by looking at the growth rate or volume doubling time. Tumor doubling time is the period of time that it takes for the tumor to double in size.

Since it would be unethical to leave a cancer untreated to see how rapidly it grew, doubling time is estimated in a number of ways. Looking at these estimates, however, doubling times have varied widely from study to study.

A 2018 study estimated doubling time by looking at serial ultrasounds between diagnosis and surgery. It was found that growth varied significantly based on the estrogen receptor status of the breast tumors. During an average interval of 57 days, 36 percent of tumors did not change in size, while 64 percent grew. Of those tumors that increased in size, the average gain in volume was 34.5 percent.

Tumors that were triple negative had greater increases in volume and shorter doubling times than those that were estrogen receptor positive and HER2 negative tumors.

In a 2016 study that similarly looked at growth based on ultrasound between diagnosis and surgery over a 31 day period, tumors increased from 1.47 centimeters to 1.56 centimeters in diameter. Daily growth rate based on type was:

  • 1.003 percent per day increase for triple negative tumors
  • 0.859 percent per day for HER2 positive/estrogen receptor negative tumors
  • 0.208 percent per day increase for estrogen receptor-positive tumors

One older study found that the doubling time of breast cancers was more rapid and fell into three categories:

  • Rapidly growing tumors: This category included roughly half of breast cancers and had doubling times of 25 days or less.
  • Intermediate growth tumors: Roughly one-third of tumors had a doubling time that fell between rapidly growing and slow-growing tumors.
  • Slow growing tumors: Around 15 percent of breast cancers fell into the slow growth category, and had doubling times that were 76 days or longer.

Other older studies have looked at growth rate via serial mammograms, with widely varying results. Overall, the average doubling time of breast cancer was 212 days but ranged from 44 days to 1800 days.

"Doubling time" is the amount of time it takes for a tumor to double in size. But it's hard to actually estimate, since factors like type of cancer and tumor size come into play. Still, several studies put the average range between 50 and 200 days.

Factors That Affect Growth Rate

A number of different studies have demonstrated some of these factors that influence the rate of growth of a breast cancer. These include:

  • The type of cancer: Inflammatory breast cancer tends to grow much more rapidly than other types of breast cancer
  • Age at diagnosis: Breast cancers in young women tend to grow more rapidly than breast cancers in older women and have a higher tumor grade
  • Menopausal state: Breast tumors often grow more rapidly for women who are premenopausal than for those who are postmenopausal, likely due to estrogen in the body
  • Receptor status: Triple negative cancers, in general, grew more rapidly than estrogen receptor-positive tumors. Triple positive tumors also grew more rapidly
  • Estrogen treatment: Women who used hormone replacement therapy after menopause had, in general, more rapid growth rate of breast tumors.
  • Ki-67 index (higher index, faster doubling time)
  • Tumor grade (higher grade, faster doubling time)

How Quickly Breast Cancer Spreads

Since the spread of breast cancer to other parts of the body (metastases) is responsible for over 90 percent of deaths related to breast cancer, the question of how rapidly breast cancer spreads is very important. Breast cancer usually spreads first to lymph nodes under the arm (lymph node-positive breast cancer). Even with the involvement of lymph nodes, breast cancer is considered an early stage and is potentially curable with treatment. When a cancer spreads to regions such as the bones, brain, lungs, or liver, however, it is considered stage 4 or metastatic breast cancer and is no longer curable.

Most breast cancers have the potential to spread. Carcinoma in situ or stage 0 breast cancer has not yet spread beyond something known as the basement membrane. These tumors are considered non-invasive and are theoretically 100 percent curable with surgery. All other stages of breast cancer (stage I to stage IV) are considered invasive and have the potential to spread.

Spread to lymph nodes, even when early stage, is very important, as these tumors have essentially declared their intent to spread beyond the breasts.

Factors Associated With More Rapid Spread

Some types of breast cancer, as well as molecular subtypes, are more likely to spread and spread earlier than other types. Ductal carcinoma is more likely to spread than lobular carcinoma, among tumors that are the same size and stage.

While many breast cancers do not spread to lymph nodes until the tumor is at least 2 centimeters to 3 centimeters in diameter, some types may spread very early, even when a tumor is less than 1 centimeter in size.

Tumor Size and Spread to Lymph Nodes

For very small and very large breast tumors, there is little association between tumor size and lymph node metastases, but for tumors in the range most commonly detected clinically, the risk of lymph nodes being involved correlates significantly with the size of the tumor.

Calculating Risk of Positive Lymph Nodes Based on Tumor Size

Memorial Sloan Kettering Cancer Center provides a Breast Cancer Nomogram through which you can predict the likelihood that a breast cancer has spread to axillary lymph nodes based on tumor size (as well as characteristics such as tumor grade, receptor status, and breast cancer type). To complete this estimate, you are asked to agree to the conditions, and understand that it is only an estimate.

How Quickly Breast Cancer Develops

You may have heard remarks that cancer has been present for five years before it is diagnosed, and this may sometimes be true. The actual time it takes for breast cancer to grow from a single cancer cell to a cancerous tumor is unknown, as estimates based on doubling time assume that this is constant throughout the duration of tumor growth.

If doubling time were constant, cancer with a doubling time of 200 days would take 20 years to develop into a detectable tumor, and a doubling time of 100 days would take 10 years to be evident on exam. In contrast, a breast tumor with a doubling time of 20 days would take only 2 years to develop. Since the majority of studies have found the average doubling time to be between 50 days and 200 days, it's likely that most breast cancers that are diagnosed began at least 5 years earlier (but again, this is assuming that growth rate is constant which it is not).

When Can Breast Cancer First Be Detected?

The earlier a breast cancer is found, the greater the chance is can be cured, and this is the theory behind mammograms and self-breast exams.

Breast Examination

The size at which a breast lump can be palpated (felt) can vary, but lumps tend to be larger when found by people themselves rather than by a physician.

When examined by a physician:

  • Breast lumps that are 0.5 to 1.0 centimeter (half an inch or less) can sometimes be felt by an experienced physician
  • Lumps that are 1.0 to 1.5 centimeters are detected around 60 percent of the time
  • Lumps that are 2.0 centimeters or greater are detected 96 percent of the time

When women perform self-exams:

  • The average size a tumor is at the time of detection is 1 centimeter in women who perform regular self-breast exams
  • For women who do not perform breast self-exams, the average size of a tumor on detection is 2.62 centimeters

While there has been controversy over whether women need to perform self-breast exams, it's clear that doing regular breast exams is likely to find a tumor when it is smaller.

Mammogram

Breast cancers are sometimes detected when very small by the presence of microcalcifications in the breast. The average size of breast cancer, when found on mammograms, is 1.1 centimeters. The earliest a tumor may be found on a mammogram is when it is between 0.2 centimeters and 0.3 centimeters in diameter.

Researchers evaluating the effectiveness of mammogram believe that increased mammograms from the 1980s until the present (and a relative decrease recently), is associated with trends in the average size of tumors at the time of diagnosis. From 1984 to 2014, the average size of breast cancer at the time of diagnosis decreased 26 percent, from 2.6 centimeters to 2.0 centimeters. A different study looked at the size of breast tumors at diagnosis from 2001 and 2014 found that, unlike earlier, the size of breast tumors increased by 3 percent to 13 percent.

Breast MRI

So far we have little data to describe the average size or the smallest size of a breast tumor that can be detected on breast MRI, though breast MRI can be a more sensitive tool for women who have a family history of familial breast cancer. A new technique called "fast MRI" may offer a higher detection rate than mammogram alone for people of average risk, especially women who have dense breast tissue.

A Word From Verywell

Breast cancers have often been present in the body for several years when they are detected, and doubling time once they are found can vary depending on the characteristics of the tumor. While women are often told they can wait to begin treatment (and a short wait is important in order to get a second opinion and prepare), waiting longer may not be advisable, especially with tumors that are triple negative or have other characteristics associated with rapid growth.

Some tumors tend to spread much earlier than others as well, and this is important to understand when choosing treatment options. For some tumors that are small and haven't spread to lymph nodes, chemotherapy may not be needed, whereas with some tumor types, should be considered for even very small tumors.

The bottom line when talking about breast cancer growth, however, is to see your doctor immediately if you have a breast lump.

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Article Sources

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  • Lee SH, Kim YS, Han W, et al. Tumor growth rate of invasive breast cancers during wait times for surgery assessed by ultrasonography. Medicine (Baltimore). 2016;95(37):e4874. DOI: 10.1097/MD.0000000000004874

  • Nakashima, K., Uematsu, T., Takahashi, K. et al. Does Breast Cancer Growth Rate Really Depend on Tumor Subtype? Measurement of Tumor Doubling Time Using Serial Ultrasonography Between Diagnosis and Surgery. Breast Cancer. 2018 Sept 26. (Epub ahead of print). DOI: 10.1007/s12282-018-0914-0

  • Sopik, V., and S. Narod. The Relationship Between Tumour Size, Nodal Status and Distant Metastases: On the Origins of Breast Cancer. Breast Cancer Research and Treatment. 2018. 170(3):647-656. DOI: 10.1007/s10549-018-4796-9