Multifocal breast cancer is a form of breast cancer in which multiple tumors arise in the same area of the breast. Treatment may include surgery, radiation therapy, chemotherapy, or a combination of treatments.

There are many types of breast cancer. The type and characteristics, including the number of tumors and where they are, can affect treatment options and long-term outlook.

This article covers information about multifocal breast cancer, including how doctors diagnose and treat the condition, the outlook, and recurrence rates.

A person who has received a diagnosis of multifocal breast cancer has more than one invasive tumor, generally in the same area of their breast.

Experts classify breast cancers into different categories depending on their characteristics. A person can receive one of the following diagnoses:

  • Unifocal breast cancer: where there is only one tumor in the breast
  • Multifocal breast cancer: when at least two invasive tumors develop in the same quadrant, or area, of the breast, and all tumors arise from one original tumor
  • Multicentric breast cancer: where at least two tumors develop separately, often in different areas of the breast

Multifocal breast cancer is not necessarily more advanced or aggressive than single-tumor breast cancer. Staging multifocal breast cancer depends primarily upon the characteristics of the primary, or largest, tumor.

However, there is more risk of larger tumors or cancer spreading to the lymph nodes, so the outlook may be less favorable for some people with multifocal compared with unifocal breast cancer.

Learn more about breast cancer.

As a result of differences in definitions and diagnostic techniques, information from 2019 states that anywhere from 6% to 60% of breast tumors are multifocal or multicentric.

One study from 2015 involving 1,158 people with breast cancer of stages 1, 2, and 3 found multifocal breast cancer in 131 of the participants, or 11.3%. They found multicentric breast cancer in 60 cases, or 5.2% of participants.

Healthcare professionals classify different types of breast cancers based on the type of cells in which cancer develops. The majority of breast cancers are carcinomas, which means they grow in the cells that line the organs and body tissues.

Classifications of breast cancer

Breast cancer is either invasive or noninvasive:

  • Noninvasive breast cancers develop inside the milk-producing glands (lobules) or inside the milk ducts and do not spread outside these areas.
  • Invasive breast cancers grow beyond the lobules or ducts and spread into other areas of the breast or parts of the body.
Was this helpful?

The main types of breast cancer include the following:

Ductal carcinoma in situ (DCIS)

DCIS initially develops in the milk ducts, and healthcare professionals consider it noninvasive. Having DCIS can increase a person’s risk of developing cancer again compared with someone who has never had breast cancer.

Lobular carcinoma in situ (LCIS)

LCIS is not considered a type of cancer. However, these noncancerous changes can increase a person’s risk of developing cancer. According to the American Cancer Society (ACS), people with LCIS have a 7 to 12 times higher risk of developing invasive breast cancer in either breast.

LCIS does not usually show on mammograms. Doctors typically discover it during a biopsy for other issues.

Invasive ductal carcinoma (IDC)

IDC is a form of breast cancer that has spread beyond the ducts and into the surrounding breast tissue. IDCs are the most common type of breast cancer, accounting for 80% of all breast cancer diagnoses, according to the ACS.

Invasive lobular carcinoma (ILC)

ILC is a form of breast cancer that has spread beyond the lobules and into the surrounding breast tissue. ILCs make up a small percentage of all breast cancer diagnoses. The ACS notes that this percentage is around 10% of invasive breast cancers.

Read more about the types of breast cancer.

Staging for multifocal breast cancer varies, with healthcare professionals basing this on the characteristics of the primary tumor and whether or not cancer is present in other areas of the body. Treatment plans and long-term outlook depend on the cancer stage.

There are five stages of breast cancer that indicate whether and how far the cancer has spread.

Stages range from noninvasive cancer that has not spread to surrounding tissue (stage 0) to metastatic cancer that has spread to other parts of the body (stage 4).

A healthcare professional can work out the cancer stage by looking at the tumor, node, and metastasis (TNM) factors. These vary among individuals:

  • Tumor (T): size and location of the largest tumor and whether it has spread to surrounding tissue
  • Node (N): whether the tumor has spread to the lymph nodes and how many lymph nodes are affected
  • Metastasis (M): whether the cancer has spread to other parts of the body, where they are, and how far from the original site

The TNM system does not include whether a tumor is multifocal or unifocal.

Read more about breast cancer stages.

Diagnosing multifocal breast cancer involves multiple examinations and, in some cases, minor procedures:

  • Breast exam: A healthcare professional will examine the breasts and chest area for signs of lumps or other changes.
  • Mammogram: A mammogram is a regular breast cancer screening procedure that captures X-ray images of the breasts. A healthcare professional examines these images for early signs of breast cancer.
  • Ultrasound: An ultrasound machine creates detailed images of the body’s internal structures in real time.
  • MRI scan: An MRI may detect multifocal breast cancers more accurately than ultrasounds and mammograms.
  • Biopsy: A biopsy is a minimally invasive procedure where a healthcare professional removes a small sample of breast tissue or part of a lymph node, which goes to a lab for testing.

Recurrence is a concern for multifocal breast cancer treatment. Recurrence refers to cancers that come back after treatment. Recurrent cancers can develop in the same place as the original tumor, or they can develop in a new location in the body.

When healthcare professionals compare multifocal breast cancer with unifocal breast cancer, the former may carry a higher risk of recurrence. However, not all studies show that this is the case, so more research is needed.

A meta-analysis from 2019 included 17 comparative studies and 7 case series, totaling 3,537 people undergoing breast-conserving surgery. The analysis demonstrated a recurrence rate of 2% to 23% following breast-conserving surgery in multifocal multicentric breast cancer at an average follow-up of 59.5 months. These are equivalent rates to those of mastectomy.

The outlook for someone with breast cancer depends on the stage of the cancer, their overall health, and their response to treatment. Experts calculate a person’s outlook by using 5-year relative survival rates.

Relative survival rate

A relative survival rate compares people with the same type and stage of breast cancer to people in the general population.

Was this helpful?

The 5-year relative survival rates for individuals with breast cancer are as follows:

  • Localized (no spread): 99%
  • Regional (localized spread to nearby structures or lymph nodes): 86%
  • Distant (spread to other areas of the body): 31%
  • Overall rate for all stages: 91%

In one study from 2015, the researchers associated multifocal breast cancer with higher mortality rates and lower 5- and 10-year survival rates, but the only independent predictors of survival were tumor size and lymph node metastases.

Compared with single-tumor breast cancers, multifocal breast cancers have a higher risk of spreading to the lymph nodes.

There is a wide variation among individuals, and scientists need to complete more research before they know how multiple tumors affect a person’s outlook.

Overall survival rates for multifocal breast cancer depend on various factors, such as

  • age
  • overall health status
  • tumor size
  • how the cancer reacts to treatment
  • if the cancer has spread beyond the original site

The appropriate treatment option can vary depending on many factors, such as the person’s age, the stage of cancer, and whether the cancer has spread to the lymph nodes or other areas of the body.

Lumpectomy

During a lumpectomy, a surgeon removes the cancerous cells while saving as much of the surrounding healthy breast tissue as possible. This procedure is especially promising if the cancer is only present in one quadrant of the breast.

Mastectomy

A mastectomy is a surgical procedure that involves removing the entire breast and the surrounding lymph nodes. Unless a tumor is larger than 5 centimeters (or 2 inches) in diameter, or large relative to the breast, doctors usually favor breast-conserving surgery, such as a lumpectomy.

Radiation therapy

Healthcare professionals may recommend radiation therapy in combination with a lumpectomy. After removing as much of the cancer as possible, they may use radiation therapy to destroy any remaining cancer cells. Radiation therapy is an effective method of preventing later breast cancer recurrence.

Chemotherapy

Chemotherapy is a systemic, or body-wide, treatment that uses one or more cytotoxic medications that prevent cancer cells from multiplying. When treating multifocal breast cancer, chemotherapy may be used either before or after the primary treatment.

Learn more about breast cancer treatments.

Breast cancer resources

Visit our dedicated hub for more research-backed information and in-depth resources on breast cancer.

Was this helpful?

Multifocal breast cancer occurs when at least two invasive tumors are present in the same quadrant of the breast. There are conflicting clinical definitions, so the exact number of people who have multifocal breast cancer and the risk of developing it remains unclear.

There are several treatment options available for multifocal breast cancer. These include lumpectomy, mastectomy, radiation therapy, hormonal therapy, and chemotherapy.

The appropriate treatment plan will vary from person to person, so it is important that people speak honestly and openly with their healthcare professionals about their treatment preferences and concerns.

Read the article in Spanish.