What is breast cancer?

Breast cancer symptoms

According to the American Cancer Society (ACS), the most commonTrusted Source symptom of breast cancer is a mass or a lump in the breast or an armpit.

Other symptoms may include:

pitting or dimpling of breast tissue, like the surface of an orange
nipple discharge
swelling
nipple or breast pain
a sunken or inverted nipple
dryness, flaking, or thickening of the breast or nipple skin
swollen lymph nodes

The ACS highlights that most breast lumps are not cancerous. However, anyone who notices a breast lump should see a healthcare professional.

Causes of breast cancer

Breast cancer developsTrusted Source due to genetic changes that can be inherited or acquired (not inherited).

Researchers associateTrusted Source an increased risk of breast cancer with factors such as:

estrogen exposure
inherited genetic irregularities
inherited genes that increase the likelihood of cancer, such as BRCA1 and BRCA2 mutations

The immune system typically attacks atypical DNA or growths, but it does not do this when a person has cancer.

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

Types of breast cancer

After puberty, female breasts consist ofTrusted Source:

fat,connective tissue,lobes, which contain tiny milk-producing glands called lobules

The most commonTrusted Source types of breast cancer are lobular carcinoma, which begins in a lobule, and ductal carcinoma, which begins in one of the tiny ducts that carry milk from the lobules to the nipples.

Invasive vs noninvasive
Invasive breast cancer involves cancerous cells spreading to nearby tissue. Cancer may then spread to other parts of the body.

In contrast, noninvasive breast cancer remains in its place of origin. Doctors may consider this a “precancerous lesion.” These cells may eventually become invasive.

Stages of breast cancer
A healthcare professional may stageTrusted Source breast cancer using something called the TNM system, which consists of five different stages. To do this, doctors examine:

primary tumor size (T)
regional lymph node status (N)
distant metastasis (M)

Each category contains substages, which can indicate specific tumor characteristics, such as whether it is positive or negative for a protein called human epidermal growth factor receptor 2 (HER2).

Staging helpsTrusted Source healthcare professionals learn whether cancer has spread and determine the best treatment options. People can speak with a doctor about cancer stages and what they mean.

Breast cancer risk factors– The following factors may make developing breast cancer more likely.

Age– The risk of breast cancer increases with age.

According to a 2024 articleTrusted Source that cites older research, around 95% of new cases occur in females older than 40.

It states that breast cancer affects 1.5 in every 100,000 females ages 20 to 24, increasing to 421.3 in every 100,000 of those ages 75 to 79.

Genetics–

Females who inherit certain mutations in the BRCA1 and BRCA2 genes have a higher chanceTrusted Source of developing breast cancer, ovarian cancer, or both. Mutations in the TP53 gene also have links to an increased breast cancer risk.

If a close relative experiences breast cancer, a person’s chance of developing breast cancer increases.

Testing guidelines– Current guidelines recommend people have genetic testing if their family history includes:

breast cancer
ovarian cancer
fallopian tube cancer
peritoneal cancer
breast cancer related to BRCA gene mutations

Around 1 in 40Trusted Source females of Ashkenazi Jewish heritage have a BRCA gene mutation. This can raise their risk of breast cancer.

Experts recommend people with this heritage consider genetic testing if a first-degree relative, such as a sister, experiences breast cancer. They also recommend it if two second-degree relatives, such as a grandmother, on the same side of the family have a history of the condition.

History of breast cancer or breast lumps–

A person with a previous history of breast cancer is more likelyTrusted Source to develop the condition than a person who has not had it before.

Having some types of noncancerous breast conditions, including atypical ductal hyperplasia or lobular carcinoma in situ, also increases the riskTrusted Source of developing breast cancer.

–Estrogen exposure and hormone treatments–

Extended exposure to estrogen and progesterone may increaseTrusted Source the risk of breast cancer. This exposure could involve starting periods early or entering menopause late.

Some researchTrusted Source associates hormone replacement therapy (HRT), specifically estrogen-progesterone therapy, with an increased risk of breast cancer.

The National Cancer Institute (NCI)Trusted Source also highlights studies suggesting that oral contraceptives may slightly increase the risk of breast cancer. However, this risk declined after stopping the use of oral contraceptives.

–Race– Although some researchTrusted Source suggests breast cancer rates are highest in the non-Hispanic white population, the Centers for Disease Control and Prevention (CDC)Trusted Source states breast cancer mortality is higher among Black females than white females.

According to a 2021 studyTrusted Source, Black females may be more susceptible to developing aggressive breast tumors.

Other researchTrusted Source points out that other factors, such as socioeconomic disparities, contribute to racial differences in treatment options and cancer mortality.

For example, a 2020 studyTrusted Source suggests difficulty accessing quality health insurance may contribute to late breast cancer diagnoses among people from marginalized groups.

Even with treatment, people are less likely to have a positive outcome when doctors diagnose breast cancer at a late stage.

—Other risk factors– The following factors may also increase the risk of breast cancer:

Obesity: Obesity after menopause may contribute to a greater likelihoodTrusted Source of developing breast cancer, possibly due to increased estrogen levels.

Regular alcohol consumption: According to the NCITrusted Source, studies consistently find that females who consume alcohol have a higher risk of breast cancer than those who do not.

Dense breast tissue: Dense breast tissue isTrusted Source a risk factor for breast cancer.

Radiation therapy: Undergoing mantle field irradiation treatment for a different cancer may increase the risk of developing breast cancer later in life.

–Cosmetic implants and breast cancer survival–

Some research in a 2023 systematic reviewTrusted Source associates certain rare cancers, such as lymphoma or squamous cell carcinoma, with breast implants.

However, the review highlights that experts generally consider breast augmentation to be safe. Other research had the following findings:

A 2015 meta-analysisTrusted Source of 17 studies that included participants who had undergone cosmetic breast augmentation found no increased risk of breast cancer associated with the procedure. The incidence among these participants was lower than expected.

Research from 2021 suggests females with cosmetic implants have significantly lower rates of breast cancer than those without.

A 2020 studyTrusted Source into the risk of breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) in 3,546 people with macro-textured breast implants found the overall BIA-ALCL risk was higher than previous literature stated. The authors highlight the need for further evaluation.

–Diagnosing breast cancer– A doctor may diagnose breast cancer during routine screening or when a person reports symptoms. The following tests and procedures can help with a diagnosis:

–Breast exams–

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–The following scans may help detect breast cancer:

Mammogram: Doctors commonly use this type of X-ray during initial breast cancer screening. It produces images that can show lumps or irregularities.

Ultrasound: This scan helpsTrusted Source a doctor evaluate the size and consistency of a lump. It may help differentiate between a solid mass and a fluid-filled cyst.

MRI: This combines different images to help doctors identify cancer or other irregularities. A doctor may recommend an MRI as a follow-up to a mammogram or ultrasound.

–Biopsy– A biopsy involves extracting a tissue sample and sending it to a laboratory for analysis. The results can show:

if cells are cancerous
the type of cancer, if present
whether the cancer is hormone-sensitive

The doctor then stages the cancer using information such as the tumor size and how far the cancer has spread. This can provide information about the person’s outlook and the best course of treatment.

Treating breast cancer– Treatment may depend on:

the type and stage of the cancer
the tumor’s sensitivity to hormones
the person’s age, overall health, and preferences
Cancer treatments can have adverse side effects. Before deciding on a treatment, people can discuss the potential risks with a doctor.

Treatment options include the following:

–Surgery– If surgery is necessary, the type will depend on the diagnosis and the person’s preferences. Types include:

Lumpectomy: A lumpectomy involves removing the tumor and a small amount of healthy tissue around it. It may be an option if the tumor is small and easy to separate from surrounding tissue.

Mastectomy: A 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.

Sentinel node biopsy: This procedure involves the removal of lymph nodes to helpTrusted Source doctors see how far cancer has spread and decide the best treatment.

Axillary lymph node dissection: If a doctor finds cancer cells in the sentinel nodes, they may recommend removing additional lymph nodes in the armpit with an axillary lymph node dissection.

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 body part.

–Radiation therapy– A person may undergo radiation therapy during or after surgery. It is most common following a lumpectomy, but some people may require radiation after a mastectomy.

This therapy involves targeting the tumor with controlled doses of radiation that kill any remaining cancer cells.

Learn more about radiation therapy.

–Chemotherapy–

A doctor may prescribe chemotherapy if there is a high risk of recurrence or spread. Chemotherapy after surgery is called adjuvant chemotherapy.

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

–Hormone-blocking therapy–

Hormone-blocking therapy may help treat estrogen receptor-positive and progesterone receptor-positive cancers. Healthcare professionals may administerTrusted Source it after surgery to prevent recurrence or beforehand to shrink the tumor.

Hormone-blocking therapy may be an option for people who cannot have surgery, chemotherapy, or radiotherapy.

Examples of hormone-blocking medications may include:

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

–Biological treatment– Targeted drugs, such as trastuzumab (Herceptin) and lapatinib (Tykerb), can destroy specific types of breast cancer.

Can people prevent breast cancer?
There is no way to prevent breast cancer. However, the following steps may help reduce the risk:

limiting alcohol consumption
eating a balanced diet
getting enough exercise
maintaining a moderate weight
Preventive surgery may also be an option for people with a high breast cancer risk.

The Bezzy Breast Cancer app provides access to an online breast cancer community where users can connect with others and gain advice and support through group discussions.