Breast cancer is a type of cancer that develops in the breast tissue. It can often be detected early through changes in the shape of the breast or nipple, or the appearance of a lump in the breast or armpit.

Although breast cancer can affect both men and women, it is much more common in women, especially those with a family history of the disease, smoking habits, obesity, or excessive alcohol use.

If breast cancer is suspected, it is important to see a primary care provider, breast specialist, or gynecologist. Treatment may involve medications, radiation therapy, or surgery, and the chances of a cure are highest when the disease is diagnosed in its early stages.

woman of color being helped by a medical provider of color during a mammogram

Common symptoms

The main symptoms of breast cancer include:

A lump in the breast or armpit;
Breast pain;
Changes in nipple shape or position;
Nipple discharge that is not breast milk;
Redness around the nipple area;
Swelling or thickening of the skin on the breast;
Changes in breast size or shape;
Sores or wounds on the breast or nipple.

In the early stages, breast cancer often causes few or no symptoms. For this reason, it’s important for women to have regular check-ups with a gynecologist and undergo breast cancer screening with mammograms when recommended.

If any of these symptoms appear, it is important to schedule an appointment with primary care doctor, gynecologist, or breast specialist as soon as possible, as early detection greatly increases the chances of successful treatment.

Male breast cancer

Although rare, breast cancer can also occur in men. Symptoms are similar to those seen in women, such as changes in the shape or position of the nipple and the appearance of a lump in the breast.

Possible causes

Breast cancer develops when mutations in the breast cells cause them to multiply uncontrollably. Both genetic and environmental factors can play a role in this process.

The main risk factors for breast cancer include:

1. Age

The risk of developing breast cancer increases with age. Women are more likely to be affected after age 45, and men after age 60. However, breast cancer can also occur in younger individuals, especially those with a family history of the disease.

2. History of breast changes

Women who have previously had breast cancer are at higher risk of developing it again in the other breast. The risk is also greater in women with benign breast conditions such as atypical hyperplasia, lobular carcinoma in situ, or high breast density detected on a mammogram.

3. Family history of cancer

People with close relatives, such as parents, siblings, or children, who have had breast or ovarian cancer have a two to three times greater risk of developing breast cancer. In these cases, genetic testing can identify BRCA1 or BRCA2 gene mutations, which help determine the level of risk and allow for closer medical monitoring and early detection.

4. Early menstruation (menarche)

Having the first period before age 12 increases lifetime exposure to estrogen, which raises the risk of developing breast cancer.

5. Menopause

Hormone replacement therapy (HRT) that contains estrogen and progesterone may increase the risk of breast cancer, especially when used for more than five years. The risk decreases after HRT is discontinued. Late menopause (after age 55) also increases risk because of longer exposure to estrogen throughout life. In addition, the use of combined hormonal contraceptives can slightly increase the risk.

6. Late pregnancy or no pregnancy

Women who have their first pregnancy after age 30 or who have never been pregnant are at higher risk of developing breast cancer.

7. Unhealthy lifestyle

A sedentary lifestyle and excess body weight can increase the likelihood of developing breast cancer, as obesity promotes cellular changes that may lead to cancer. Excessive alcohol consumption also raises the risk.

8. Previous radiation therapy

People who have undergone radiation therapy to the chest (especially at a young age, such as during treatment for Hodgkin’s lymphoma) are at greater risk of developing breast cancer.

9. Hormone therapy for prostate cancer

In men, estrogen-based hormone therapy used to treat prostate cancer can increase the risk of breast cancer. Other contributing factors include undescended testicles, testicular inflammation, surgical removal of the testicles, Klinefelter syndrome, and liver cirrhosis.

Types of breast cancer

The main types of breast cancer include:

Lobular carcinoma in situ: considered more of a risk factor than an actual tumor;
Ductal carcinoma in situ: abnormal breast cells that can develop into cancer if left untreated;
Invasive ductal carcinoma: the most common type of breast cancer;
Invasive lobular carcinoma: the second most common type.

Identifying the specific type of breast cancer is done through a breast biopsy, which helps determine the most appropriate treatment plan.

Confirming a diagnosis

Diagnosis of breast cancer is made by a doctor (such as a primary care provider, gynecologist, or breast specialist) who may order imaging tests like a mammogram, breast ultrasound, or MRI. A biopsy is then performed to confirm whether cancer cells are present.

Breast cancer staging

Breast cancer is classified according to the size and spread of the tumor:

T1: tumor smaller than 2 cm;
T2: tumor between 2 and 5 cm;
T3: tumor larger than 5 cm;
T4: tumor involving the skin or chest wall.

Lymph node involvement is classified as:

N1: mobile lymph nodes on the same side as the tumor;
N2: fixed lymph nodes on the same side of the tumor that are no longer mobile;
N3: other lymph nodes affected.

If the cancer spreads to distant organs such as the bones, lungs, or liver, it is classified as M1 (metastatic). Early-stage breast cancer is usually small and localized, while advanced-stage cancer may involve distant organs and can be more difficult to treat surgically.

Treatment options

Breast cancer treatment depends on the type and stage of the disease. It may include one or more of the following options:

1. Surgery

Surgery involves removing the tumor, and in some cases, the entire breast (mastectomy). It can be combined with radiation therapy. Reconstructive surgery can be performed afterward to restore the breast’s appearance while maintaining oncologic safety.

2. Radiation therapy

Radiation therapy uses focused radiation to destroy cancer cells. It may be performed before surgery to shrink the tumor or after surgery to eliminate any remaining cancer cells.

3. Chemotherapy

Chemotherapy involves using medications to destroy or slow the growth of cancer cells. It may be given for three to six months, either before or after surgery, depending on the individual case.

4. Hormone therapy

Hormone therapy involves medications such as tamoxifen or aromatase inhibitors (anastrozole, letrozole, or exemestane) to block estrogen’s effects and prevent tumor growth. It is used for hormone receptor–positive breast cancers to help reduce the risk of recurrence after surgery.

5. Targeted therapy

Targeted therapy uses specific drugs that attack cancer cells with certain receptors. These medications include ribociclib, abemaciclib, trastuzumab, pertuzumab, bevacizumab, and nivolumab.

Can breast cancer be cured?

Breast cancer can often be cured, especially when it is diagnosed early, before spreading to other parts of the body.

Prevention measures

The main ways to reduce the risk of breast cancer include:

Exercising regularly;
Maintaining a healthy weight;
Limiting alcohol consumption;
Avoiding smoking.

For individuals at very high risk of breast cancer, preventive measures such as taking tamoxifen or aromatase inhibitors (anastrozole, letrozole, or exemestane) or undergoing preventive breast removal surgery (prophylactic mastectomy) may be considered under medical supervision.

Breast Cancer: Symptoms, Causes & Treatment