Breast cancer is the most common invasive cancer in females. It is also a leading cause of cancer deaths among females.

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Advances in screening and treatment for breast cancer have improved survival rates dramatically. Overall, the rate of breast cancer declined by about 40% between 1989 and 2017.

A 2019 study showed, however, that the rate in the United States may no longer be declining in women aged 20–39 years.

The American Cancer Society (ACS) reports that:

  • There are more than 3.8 million breast cancer survivors in the U.S.
  • The chance of dying from breast cancer is around 1 in 38 (2.6%).
  • About 281,550 new cases of invasive breast cancer will be diagnosed by the end of 2021
  • About 43,600 deaths from breast cancer are likely to occur by the end of 2021

Awareness of the symptoms and the need for screening is key in reducing the risk of mortality.

In rare instances, breast cancer can also affect males. This article will focus on breast cancer in females.

Learn about breast cancer in males here.

The first symptom of breast cancer is usually an area of thickened tissue in the breast or a lump in the breast or an armpit.

Other symptoms include:

  • armpit or breast pain does not change with the monthly cycle
  • pitting, like the surface of an orange, or color changes such as redness in the skin of the breast
  • a rash around or on one nipple
  • discharge from a nipple, which may contain blood
  • a sunken or inverted nipple
  • a change in the size or shape of the breast
  • peeling, flaking, or scaling of the skin of the breast or nipple

Most breast lumps are not cancerous. However, anyone who notices a breast lump should have it checked by a healthcare professional.

A lump or a mass in the breast is often one of the first signs of breast cancer. In many cases, these lumps are painless. A person may experience pain in the nipple or breast area that appears to be tied to their menstrual cycle.

Pain caused by breast cancer is typically gradual. Anyone who experiences breast pain, especially if it is severe or persistent, should consult a healthcare professional.

After puberty, a female’s breasts are made up of fat, connective tissue, and thousands of lobules. These are tiny glands that can produce milk. Tiny tubes, or ducts, carry the milk toward the nipple.

Breast cancer develops as a result of genetic mutations or damage to DNA. These can be associated with exposure to estrogen, inherited genetic defects, or inherited genes that can cause cancer, such as the BRCA1 and BRCA2 genes.

When a person is healthy, their immune system attacks any abnormal DNA or growths. When a person has cancer, this does not happen.

As a result, cells within breast tissue begin to multiply uncontrollably, and they do not die as usual. This excessive cell growth forms a tumor that deprives surrounding cells of nutrients and energy.

Breast cancer usually starts in the inner lining of the milk ducts or the lobules that supply them with milk. From there, it can spread to other parts of the body.

A doctor determines the stage of cancer according to the size of the tumor and whether it has spread to lymph nodes or other parts of the body.

There are different ways to stage breast cancer. One includes stages 0–4 with subcategories at each stage. Below, we describe each of these main stages. Substages can indicate specific characteristics of a tumor, such as its HER2 receptor status.

  • Stage 0: This is also called ductal carcinoma in situ. The cancerous cells are only within the ducts and have not spread to surrounding tissues.
  • Stage 1: At this stage, the tumor measures up to 2 centimeters (cm) across. It has not affected any lymph nodes, or there are small groups of cancer cells in lymph nodes.
  • Stage 2: The tumor is 2 cm across and has started to spread to nearby nodes, or it is 2–5 cm across and has not spread to the lymph nodes.
  • Stage 3: The tumor is up to 5 cm across and has spread to several lymph nodes, or the tumor is larger than 5 cm and has spread to a few lymph nodes.
  • Stage 4: The cancer has spread to distant organs, most often the bones, liver, brain, or lungs.

The following factors make developing breast cancer more likely, and some may be preventable.

Age

The risk of breast cancer increases with age. At 20 years old, the chance of developing breast cancer in the next decade is 0.06%. By the age of 70, this figure goes up to 3.84%.

Genetics

A person with certain mutations in the BRCA1 and BRCA2 genes has a higher chance of developing breast cancer, ovarian cancer, or both. People inherit these genes.

Mutations in the TP53 gene also have links to increased breast cancer risk.

If a close relative has or has had breast cancer, a person’s chance of developing breast cancer increases.

Current guidelines recommend that people receive genetic testing if they have a family history of breast, ovarian, fallopian tube, or peritoneal cancer.

People should also receive this testing, the guidelines state, if there is a history of breast cancer related to BRCA1 or BRCA2 gene mutations in their ancestry. This applies to people, for example, with Ashkenazi Jewish ancestry.

History of breast cancer or breast lumps

A person who has had breast cancer is more likely to develop it again than a person with no history of the disease.

Having some types of noncancerous breast lumps increases the risk of developing the cancer later on. Examples include atypical ductal hyperplasia or lobular carcinoma in situ.

People with a history of breast, ovarian, fallopian tube, or peritoneal cancer should ask their doctors about genetic testing.

Dense breast tissue

Dense breast tissue is more likely to be associated with a diagnosis of breast cancer.

Read more about dense breast tissue here.

Estrogen exposure and breastfeeding

Extended exposure to estrogen appears to increase the risk of breast cancer.

This exposure could involve starting periods at an early age or entering menopause late. Between these times, estrogen levels in the body are higher.

Breastfeeding, especially for over 1 year, appears to reduce the risk of developing breast cancer. This may be due to the drop in estrogen exposure that follows pregnancy and breastfeeding.

Body weight

Obesity after menopause may contribute to a greater likelihood of developing breast cancer, possibly due to increased estrogen levels. High sugar intake may also be a factor.

Alcohol consumption

Regularly drinking high amounts of alcohol appears to play a role in breast cancer development.

According to the National Cancer Institute (NCI), studies have consistently found that women who consume alcohol have a higher risk of breast cancer than women who do not. And those who drink moderate to heavy levels have a greater risk than women who drink less.

Radiation exposure

Undergoing radiation treatment for a different cancer may increase the risk of developing breast cancer later in life.

Hormone treatments

Studies have shown that oral contraceptives may slightly increase the risk of breast cancer, the NCI reports.

And according to the ACS, studies have found that hormone replacement therapy, specifically estrogen-progesterone therapy, is related to an increased risk of breast cancer.

Race

As the Centers for Disease Control and Prevention (CDC) report, breast cancer mortality is about 40% higher among Black women than white women.

Other research has found that African American women are more likely to die of breast cancer than any other group.

The reasons for this are likely biological and socioeconomic. For example, according to a 2021 study, Black women may be more susceptible to developing aggressive breast tumors.

Other research points out that factors such as low socioeconomic status also contribute to cancer racial disparities. Having this status makes it difficult for people from marginalized groups to access quality health insurance, which in the U.S., is often tied to a person’s employment.

A 2020 study on the association of insurance status and the detection of early stage breast cancer showed how difficulty accessing healthcare may be part of the reason why people from marginalized groups often receive breast cancer diagnoses at a late stage, when survival, even with treatment, is less likely.

Cosmetic implants and breast cancer survival

The general agreement, based on research, is that silicone breast implants do not increase the risk of breast cancer.

A 2015 meta-analysis of 17 studies that included participants who had undergone cosmetic breast augmentation discovered no increase in the risk of breast cancer associated with the procedure. In fact, the research showed that the incidence among these participants was lower than expected.

In 2021, another study found that women with cosmetic implants have significantly lower rates of breast cancer than those who do not have them.

Meanwhile, a 2013 meta-analysis found that women who received a diagnosis of breast cancer after getting cosmetic breast implants may have a higher risk of dying from the disease.

However, this research did not factor in other variables that may influence breast cancer mortality, such as body mass index, age at diagnosis, or cancer stage at diagnosis. And at least one of the studies in the analysis looked at overall mortality, instead of breast cancer-specific mortality, thereby potentially skewing the results. As such, a person should consider the finding with caution.

There are several types of breast cancer. The most common type is ductal carcinoma, which begins in a milk duct. Another type is lobular carcinoma, which begins in a lobule, one of the tiny glands that produce milk.

“Invasive” breast cancer involves cancerous cells spreading to nearby tissue. It is then more likely that the cancer will spread to other parts of the body.

“Noninvasive” breast cancer remains in its place of origin. These cells may eventually become invasive.

A doctor often diagnoses breast cancer as a result of routine screening or when a person reports symptoms. Below, we describe tests and procedures that can help the doctor make and confirm the diagnosis.

Breast exam

This involves checking the breasts for lumps and other possible indications of cancer.

During the examination, the person may need to sit or stand with their arms in different positions, such as above their head or by their sides.

Imaging tests

Several types of scans can help detect breast cancer, including:

Mammogram: This is a type of X-ray that doctors commonly use during initial breast cancer screening. It produces images that can show lumps or abnormalities. If there is any sign of a potential problem, the doctor usually conducts further testing.

Ultrasound: This scan uses sound waves to help a doctor differentiate between a solid mass and a fluid-filled cyst.

MRI: This combines different images of the breast to help a doctor identify cancer or other abnormalities. A doctor may recommend an MRI as a follow-up to a mammogram or ultrasound. Doctors may also use MRIs to screen people with a higher risk of breast cancer.

Here, learn more about how to prepare for a mammogram.

Biopsy

This involves extracting a sample of tissue and sending it to a laboratory for analysis.

The results show whether the cells are cancerous, and if they are, which type of cancer has developed. The results can even show whether the cancer is hormone-sensitive.

The doctor then stages the cancer to establish:

  • the size of a tumor
  • how far it has spread
  • whether it is invasive

This can provide information about the outlook and the best course of treatment.

The most effective approach depends on several factors, including:

  • the type and stage of the cancer
  • the sensitivity to hormones
  • the person’s age, overall health, and preferences

The main treatment options include:

Surgery

If surgery is necessary, the type depends on the diagnosis and the person’s preferences. Types of surgery include:

Lumpectomy: This involves removing the tumor and a small amount of healthy tissue around it.

A lumpectomy can help prevent the spread of cancer. This may be an option if the tumor is small and easy to separate from surrounding tissue.

Mastectomy: A simple mastectomy involves removing the breast’s lobules, ducts, fatty tissue, nipple, areola, and some skin. In some types, a surgeon also removes the lymph nodes and muscle in the chest wall.

Here, learn about the different types of mastectomy.

Sentinel node biopsy: If breast cancer reaches the sentinel lymph nodes, the first nodes to which it can spread, it can travel to other parts of the body through the lymphatic system. If the doctor does not find cancer in the sentinel nodes, it is usually not necessary to remove other nodes.

Axillary lymph node dissection: If a doctor finds cancer cells in the sentinel nodes, they may recommend removing several lymph nodes in the armpit. This can prevent cancer from spreading.

Reconstruction: Following a mastectomy, a surgeon can reconstruct the breast so that it looks more natural. This can help a person cope with the psychological effects of breast removal.

The surgeon can reconstruct the breast during the mastectomy or at a later date. They may use a breast implant or tissue from another part of the body.

Find out more about breast reconstruction surgery.

Radiation therapy

A person may undergo radiation therapy around 1 month after surgery. It involves targeting the tumor with controlled doses of radiation that kill any remaining cancer cells.

Learn more about the benefits and adverse effects of radiation therapy.

Chemotherapy

A doctor may prescribe cytotoxic chemotherapy drugs to kill cancer cells if there is a high risk of recurrence or spread. When a person has chemotherapy after surgery, doctors call it adjuvant chemotherapy.

Sometimes, a doctor may recommend chemotherapy before surgery to shrink the tumor and make it easier to remove. This is called neoadjuvant chemotherapy.

Learn more about chemotherapy here.

Hormone-blocking therapy

Doctors use hormone-blocking therapy to prevent hormone-sensitive breast cancers from returning after treatment. The therapy may help treat estrogen receptor-positive and progesterone receptor-positive cancers.

Healthcare professionals usually administer it after surgery, though they may do so beforehand to shrink the tumor.

Hormone-blocking therapy may be the only option for people who are not suitable candidates for surgery, chemotherapy, or radiotherapy.

Examples of hormone-blocking medications may include:

  • tamoxifen (Nolvadex)
  • aromatase inhibitors
  • ovarian ablation or suppression
  • goserelin (Zoladex)

This type of treatment may affect fertility.

Biological treatment

Targeted drugs can destroy specific types of breast cancer. Examples include:

  • trastuzumab (Herceptin)
  • lapatinib (Tykerb)
  • bevacizumab (Avastin)

Treatments for breast cancer and other cancers can have severe adverse effects. When deciding on a treatment, discuss the potential risks with a doctor and look for ways to minimize the side effects.

There is no way to prevent breast cancer. However, a person can take steps to significantly reduce their risk.

These include:

  • limiting alcohol consumption, for people who drink
  • having a healthy diet with plenty of fresh fruit and vegetables
  • getting enough exercise
  • maintaining a moderate body mass index

A person who is considering using hormone replacement therapy after menopause may wish to discuss this with a healthcare professional.

For people with a high risk of breast cancer, preventive surgery is also an option.

The Breast Cancer Healthline app provides access to an online breast cancer community, where users can connect with others and gain advice and support through group discussions. It also classifies survival rates based on how far cancer has spread beyond the breast tissue.

Breast cancer screening

Expert guidelines about how often to have breast cancer screenings differ.

The American College of Physicians recommends that women aged 40–49 years with an average risk of breast cancer discuss the benefits and risks of regular screenings with a doctor.

Women aged 50–74 who have an average risk, the guidelines say, should have screenings every 2 years. Women aged 75 or older should continue with screenings if their life expectancy is 10 or more years.

The ACS suggests that women with an average risk should be able to choose whether to have yearly scans from the age of 40 onward. Regular annual screening should start at the age of 45, and at the age of 55, a woman should be able to decide whether to start screening every other year, these guidelines state.

The American College of Radiologists recommend screenings every year, starting from 40 years of age.

Despite the variations, most experts recommend at least speaking with a doctor about breast cancer screening from the age of 40 onward.

A survival rate describes how long a person with breast cancer is likely to live after the diagnosis, in comparison with someone who does not have the diagnosis.

The NCI currently estimates that about 90% of females with breast cancer survive for at least 5 years after the diagnosis.

It is important to keep in mind that researchers use survival rates to assess large populations. And in calculating this rate, they exclude the risk of dying from other causes.

A survival rate cannot predict an individual’s outlook. No two people necessarily respond to treatment in the same way.

Find more detailed information about survival rates by cancer stage.

Breast cancer is still a leading cause of cancer death among females. However, the 5-year survival rate is high, and the rate of diagnosis has been largely declining for more than three decades. Having said that, the rates in the U.S. may no longer be declining in women aged 20–39 years.

A person may be able to take steps to prevent breast cancer, such as maintaining a healthy lifestyle and speaking with their doctor about the best pace of screening, beginning at age 40.

Read the article in Spanish.