Breast cancer is a malignancy that originates in the cells of the breasts. It stands as the most prevalent invasive cancer among women and is the second leading cause of cancer-related deaths in women, surpassed only by lung cancer.

Symptoms

The initial indications of breast cancer typically involve an area of thickened tissue or a lump within the breast or armpit.

Symptoms may include:

• Pain in the armpits or breast that does not fluctuate with the menstrual cycle

• Pitting or redness of the breast skin, resembling an orange peel texture

• A rash on or around one of the nipples

• Nipple discharge, which may contain blood

• A nipple that appears sunken or inverted

• A change in the size or shape of the breast

• Peeling, flaking, or scaling of the skin on the breast or nipple

• A lump or thickening within the breast

• Alterations to the skin or the nipple

• Swelling in all or part of the breast

• A sudden, unexplained change in the breast’s shape or size

While most lumps are benign, it is crucial for women to have them examined by a healthcare professional, as an early diagnosis of breast cancer significantly improves the chances of recovery.

Stages

Cancer is staged based on the tumor’s size and whether it has spread to lymph nodes or other parts of the body.

There are various methods for staging breast cancer. One common approach ranges from stage 0 to 4, which can be further subdivided into smaller stages.

• Stage 0: Known as ductal carcinoma in situ (DCIS), the cancerous cells are confined within a duct and have not invaded surrounding tissues.

• Stage 1: At the onset of this stage, the tumor measures up to 2 centimeters (cm) across and has not affected any lymph nodes.

• Stage 2: The tumor is 2 cm across and has begun to spread to nearby lymph nodes.

• Stage 3: The tumor measures up to 5 cm across and may have spread to some lymph nodes.

• Stage 4: The cancer has metastasized to distant organs, particularly the bones, liver, brain, or lungs. This is also referred to as metastatic breast cancer.

Causes

Following puberty, a woman’s breast comprises fat, connective tissue, and thousands of lobules—tiny glands responsible for producing milk during breastfeeding. Small tubes, or ducts, transport the milk towards the nipple.

In cancer, the body’s cells multiply uncontrollably. This excessive cell growth is what leads to cancer.

Breast cancer typically originates in the inner lining of milk ducts or the lobules that supply them with milk. From these locations, it can spread to other parts of the body.

Risk factors

The precise cause of breast cancer remains unclear, but several risk factors increase its likelihood. Some of these factors are preventable.

1. Age: The risk increases with age. At 20 years old, the chance of developing breast cancer in the subsequent decade is 0.6 percent. By the age of 70 years, this figure rises to 3.84 percent.

2. Genetics: If a close relative has or has had breast cancer, the individual’s risk is elevated. Women who carry the BRCA1 and BRCA2 genes have a higher risk of developing breast cancer, ovarian cancer, or both. These genes can be inherited. TP53 is another gene linked to an increased breast cancer risk.

3. A history of breast cancer or breast lumps: Women who have previously had breast cancer are more prone to recurrence compared to those with no history of the disease. Certain types of benign, or non-cancerous, breast lumps, such as atypical ductal hyperplasia or lobular carcinoma in situ, increase the likelihood of developing cancer later.

4. Dense breast tissue: Breast cancer is more likely to develop in breast tissue with higher density.

5. Estrogen exposure and breast-feeding: Prolonged exposure to estrogen appears to increase the risk of breast cancer. This could be due to starting menstruation earlier or entering menopause later than average, as estrogen levels are higher during these periods. Breastfeeding, especially for over 1 year, seems to reduce the chance of developing breast cancer, possibly because pregnancy followed by breastfeeding lowers estrogen exposure.

6. Body weight: Women who are overweight or obese after menopause may face a higher risk of developing breast cancer, potentially due to elevated estrogen levels. High sugar intake might also be a contributing factor.

7. Alcohol consumption: A higher rate of regular alcohol consumption appears to play a role. Studies indicate that women who consume more than 3 drinks per day have a 1.5 times higher risk.

8. Radiation exposure: Undergoing radiation treatment for a cancer unrelated to the breast increases the risk of breast cancer later in life.

9. Hormone treatments: The use of hormone replacement therapy (HRT) and oral birth control pills has been linked to breast cancer due to increased estrogen levels.

10. Occupational hazards: In 2012, researchers concluded that exposure to certain carcinogens and endocrine disruptors, for example, in the workplace, could be associated with breast cancer. In 2007, scientists suggested that working night shifts might increase the risk of breast cancer, though more recent research suggests this is unlikely.

Additional risk factors include:

• Obesity: Being obese increases the risk of breast cancer.

• Early onset of menstruation: Beginning menstruation before age 12 increases the risk of breast cancer.

• Late onset of menopause: If menopause began at an older age, the likelihood of developing breast cancer is higher.

• First child at an older age: Women who give birth to their first child after age 30 may have an increased risk of breast cancer.

• Never having been pregnant: Women who have never been pregnant have a greater risk of breast cancer than those who have had one or more pregnancies.

• Postmenopausal hormone therapy: Women who take hormone therapy medications combining estrogen and progesterone to manage menopausal symptoms have an increased risk of breast cancer. This risk decreases when these medications are discontinued.

• Alcohol consumption: Drinking alcohol increases the risk of breast cancer.

• Dense breast tissue: Dense breast tissue makes mammograms challenging to interpret and also increases the risk of breast cancer.

Types

There are several types of breast cancer, generally categorized into “invasive” and “noninvasive” (or in situ). Invasive cancer has spread from the breast ducts or glands to other parts of the breast, while noninvasive cancer has not spread from the original tissue.

These two categories describe the most common types of breast cancer, which include:

• Ductal carcinoma in situ (DCIS): A noninvasive condition where cells lining the breast ducts undergo cancerous changes but have not invaded the surrounding breast tissue.

• Lobular carcinoma in situ (LCIS): Cancer that develops in the milk-producing glands of the breast. Like DCIS, the cancer cells have not yet invaded the surrounding tissue.

• Invasive ductal carcinoma (IDC): The most common type of breast cancer. It begins in the breast’s milk ducts and then invades nearby breast tissue. Once it has spread beyond the milk ducts, it can begin to spread to other nearby organs and tissues.

• Invasive lobular carcinoma (ILC): This type first develops in the breast’s lobules. If diagnosed as ILC, the cancer has already spread to nearby tissue and organs.

Other, less common types of breast cancer include:

• Paget disease of the nipple: This breast cancer originates in the breast ducts but, as it grows, affects the skin and areola of the nipple.

• Phyllodes tumor: A very rare type of breast cancer that grows in the connective tissue of the breast.

• Angiosarcoma: A cancer that develops on the blood vessels or lymph vessels in the breast.

The specific type of cancer influences treatment options and the prognosis (likely long-term outcome).

Diagnosis

A diagnosis often results from routine screening or when a woman consults her doctor after detecting symptoms.

Several diagnostic tests and procedures help confirm a diagnosis:

• Breast exam: The physician will examine the patient’s breasts for lumps and other symptoms. The patient will be asked to sit or stand with her arms in various positions, such as above her head and by her sides.

• Imaging tests:

  • A mammogram is a type of X-ray commonly used for initial breast cancer screening. It produces images that can help detect lumps or abnormalities. A suspicious result may warrant further diagnosis. However, mammography can sometimes show suspicious areas that are not cancerous, potentially leading to unnecessary stress and interventions.

  • An ultrasound scan can help differentiate between a solid mass and a fluid-filled cyst.

  • An MRI scan involves injecting a dye into the patient to ascertain how far the cancer has spread.

• Biopsy: A tissue sample is surgically removed for laboratory analysis. This can determine if the cells are cancerous, the specific type of cancer, and whether it is hormone-sensitive.

Diagnosis also involves staging the cancer to establish:

• The size of a tumor

• How far it has spread

• Whether it is invasive or non-invasive

• Whether it has metastasized, or spread to other parts of the body

Staging will impact the chances of recovery and guide the selection of the most appropriate treatment options.

Treatment

Treatment strategies depend on:

• The type of breast cancer

• The stage of the cancer

• Sensitivity to hormones

• The patient’s age, overall health, and preferences

The main treatment options include:

• Radiation therapy

• Surgery

• Biological therapy, or targeted drug therapy

• Hormone therapy

• Chemotherapy

Factors influencing a person’s choice will include the cancer’s stage, other medical conditions, and their individual preference.

Surgery

If surgery is required, the choice will depend on the diagnosis and the individual patient. Types of surgery include:

• Lumpectomy: This involves removing the tumor and a small margin of healthy tissue around it to help prevent cancer spread. This may be an option if the tumor is small and can be easily separated from surrounding tissue.

• Mastectomy: A simple mastectomy involves removing the lobules, ducts, fatty tissue, nipple, areola, and some skin. A radical mastectomy will also remove chest wall muscle and lymph nodes in the armpit.

• Sentinel node biopsy: Removing one lymph node can help prevent cancer spread, as if breast cancer reaches a lymph node, it can disseminate further through the lymphatic system to other parts of the body.

• Axillary lymph node dissection: If cancer cells are found in a sentinel node, the healthcare professional may recommend removing several lymph nodes in the armpit to prevent disease spread.

• Reconstruction: Following breast surgery, a surgeon can perform reconstruction to recreate the breast, aiming for a similar appearance to the other breast. This can be done concurrently with a mastectomy or at a later date, using a breast implant or tissue from another part of the patient’s body.

Radiation therapy

Controlled doses of radiation are directed at the tumor to destroy cancer cells. A person may undergo this approximately a month after surgery, often in conjunction with chemotherapy, to eliminate any remaining cancer cells.

Each session lasts a few minutes, and a person may require three to five sessions per week for 3-6 weeks, depending on the treatment goal and the cancer’s extent.

The type of breast cancer will determine the most suitable type of radiation therapy, if any. Adverse effects can include fatigue, lymphedema, darkening of the breast skin, and irritation of the breast skin.

Chemotherapy

A doctor may prescribe cytotoxic drugs to kill cancer cells if there is a high risk of recurrence or spread. This is known as adjuvant chemotherapy.

If a tumor is large, a specialist might administer chemotherapy before surgery to shrink the tumor and facilitate its removal. This is termed neo-adjuvant chemotherapy.

Chemotherapy can also treat cancer that has metastasized, or spread to other parts of the body, and can alleviate some symptoms, especially in later stages. It can also reduce estrogen production, as estrogen can promote the growth of certain breast cancers.

Adverse effects of chemotherapy may include:

• Nausea

• Vomiting

• Loss of appetite

• Fatigue

• Sore mouth

• Hair loss

• A slightly increased susceptibility to infections

However, medications can help manage many of these side effects.

Hormone blocking therapy

Doctors utilize hormone blocking therapy to prevent recurrence in hormone-sensitive breast cancers, specifically estrogen receptor (ER)-positive and progesterone receptor (PR)-positive cancers.

Hormone blocking therapy is typically administered after surgery, but it might sometimes be used beforehand to shrink the tumor. It may be the sole option for patients unable to undergo surgery, chemotherapy, or radiotherapy.

The effects usually last for up to 5 years after surgery. However, this treatment will have no effect on cancers that are not sensitive to hormones.

Examples of hormone blocking therapy medications may include:

• Tamoxifen

• Aromatase inhibitors

• Ovarian ablation or suppression

• A luteinizing hormone-releasing hormone agonist drug called Goserelin, which suppresses the ovaries

Hormone treatment may impact a woman’s future fertility.

Biological treatment

Targeted drugs can destroy specific types of breast cancer. Examples include trastuzumab (Herceptin), lapatinib (Tykerb), and bevacizumab (Avastin). These drugs are administered for various purposes.

Treatments for breast and other cancers can have severe adverse effects. Therefore, when deciding on a treatment, patients should discuss the associated risks and ways to minimize negative effects with their doctor.

PREVENTION

There is no definitive way to prevent breast cancer, but certain lifestyle choices can significantly reduce the risk of breast and other types of cancer.

These include:

• Breast cancer screening: Consult a doctor about when to begin breast cancer screening exams and tests, such as clinical breast exams and mammograms.

• Breast self-exam for breast awareness.

• Avoiding excessive alcohol consumption.

• Following a healthy diet rich in fresh fruit and vegetables.

• Engaging in sufficient exercise.

• Maintaining a healthy body weight.

• Limiting postmenopausal hormone therapy.

Women should carefully consider their options regarding breastfeeding and the use of HRT following menopause, as these can influence the risk.

Preventive surgery and preventive medication (chemoprevention) are options for women at high risk.