Key facts
- Breast cancer caused 670 000 deaths globally in 2022.
- Roughly half of all breast cancers occur in women with no specific risk factors other than sex and age.
- Breast cancer was the most common cancer in women in 157 countries out of 185 in 2022.
- Breast cancer occurs in every country in the world.
- Approximately 0.5–1% of breast cancers occur in men.
Overview
When aberrant breast cells proliferate uncontrollably and develop into tumors, it is known as breast cancer. The tumors have the potential to spread throughout the body and become lethal if untreated.
The milk ducts and/or the breast’s milk-producing lobules are where breast cancer cells start. The earliest type, known as in situ, is detectable in its early stages and poses no harm to life. Cancer cells have the ability to invade neighboring breast tissue. Tumors resulting from this induce thickening or lumps.
It is possible for invasive tumors to metastasis, or spread, to other organs or surrounding lymph nodes. Metastasis can be deadly and life-threatening.
The milk ducts and/or the breast’s milk-producing lobules are where breast cancer cells start. The earliest type, known as in situ, is detectable in its early stages and poses no harm to life. Cancer cells have the ability to invade neighboring breast tissue. Tumors resulting from this induce thickening or lumps.
It is possible for invasive tumors to metastasis, or spread, to other organs or surrounding lymph nodes.
Problems
In 2022, 2.3 million women received a breast cancer diagnosis, and 670,000 people died from the disease worldwide. In any nation on earth, breast cancer can strike women at any age after puberty, though its incidence rises with age.
Global estimations show glaring disparities in the incidence of breast cancer based on human development. For example, 1 in 12 women may receive a breast cancer diagnosis over their lifetime and 1 in 71 will pass away from the disease in nations with extremely high Human Development Indexes (HDIs).
In comparison, 1 in 48 women will die from breast cancer in nations with a low HDI, even though only 1 in 27 women will receive a breast cancer diagnosis during their lifetime.
Risk
The biggest risk factor for breast cancer is being a woman. Women are affected by breast cancer in about 99% of cases, while men are affected in 0.5–1% of cases. Men with breast cancer are treated according to the same management guidelines as women.
Age, obesity, hazardous alcohol use, radiation exposure history, family history of breast cancer, reproductive history (including the age at which menstruation started and the age of the first pregnancy), tobacco use, postmenopausal hormone therapy, and other factors all raise the risk of breast cancer. Approximately 50% of breast cancers occur in women who have no discernible risk factors for the disease other than their age (over 40) and gender (female).
Although the majority of women who are diagnosed with breast cancer do not have a known family history of the disease, having a family history of breast cancer increases the chance of developing breast cancer. A woman is not always at lower risk just because her family history is unknown.
The most common inherited high penetrance gene mutations that significantly raise the risk of breast cancer are those in the BRCA1, BRCA2, and PALB-2 genes. Women who have mutations in these key genes may think about risk-reduction measures like chemoprevention or surgically removing both breasts.
Signs and symptoms
Early detection is crucial because the majority of people won’t exhibit any symptoms when the cancer is still in its early stages.
Combinations of symptoms are common in breast cancer, particularly in more advanced stages. Breast cancer symptoms can include:
- a breast lump or thickening, often without pain
- change in size, shape or appearance of the breast
- dimpling, redness, pitting or other changes in the skin
- change in nipple appearance or the skin surrounding the nipple (areola)
- abnormal or bloody fluid from the nipple.
Even if an atypical breast lump doesn’t ache, people should still get medical attention.
Most bumps on the breast are not cancerous. Cancerous breast lumps that are tiny and have not migrated to neighboring lymph nodes have a better chance of being effectively treated.
Breast cancers can cause additional symptoms and spread to other parts of the body. Although it is possible to have cancer-bearing lymph nodes that are not palpable, the lymph nodes under the arm are frequently the most frequently found initial site of dissemination.
Cancerous cells have the potential to spread over time to other organs, such as the brain, liver, lungs, and bones. New cancer-related symptoms, such headaches or bone pain, may manifest once they reach these locations.
Treatment
The subtype of breast cancer and the extent to which it has spread to lymph nodes (stages II or III) or other regions of the body (stage IV) determine the course of treatment.
To reduce the likelihood that the cancer will return (recur), doctors combine different treatments. These consist of:
- surgery to remove the breast tumour
- radiation therapy to reduce recurrence risk in the breast and surrounding tissues
- medications to kill cancer cells and prevent spread, including hormonal therapies, chemotherapy or targeted biological therapies.
Breast cancer treatments that are initiated early and completed are more effective and more tolerated.
Surgery can remove the entire breast (mastectomy) or just the malignant tissue (lumpectomy). In order to determine whether the cancer has the potential to spread, surgery may also remove lymph nodes.
Radiation therapy reduces the likelihood of cancer reoccurring on the chest wall and treats microscopic malignancies that are still present in the breast tissue and/or lymph nodes.
Although they are not always unpleasant, advanced malignancies can erode through the skin to produce open sores, or ulcerations. Women who have non-healing breast sores should see a doctor so that a biopsy can be done.
The biological characteristics of breast cancer, as identified by specialized testing (tumor marker determination), are taken into consideration when choosing medications to treat the disease. The WHO Essential Medicines List (EML) already includes the vast majority of medications used to treat breast cancer.
For aggressive tumors, lymph nodes are removed during cancer surgery. In the past, it was believed that in order to stop cancer from spreading, the lymph node bed beneath the arm had to be completely removed (full axillary dissection). Due to its lower risk of problems, a smaller lymph node operation known as “sentinel node biopsy” is currently recommended.
Based on the biological subtyping of the malignancies, medical treatments for breast cancers can be administered either before (“neoadjuvant”) or after (“adjuvant”) surgery. Triple negative breast cancer, which does not express the estrogen receptor (ER), progesterone receptor (PR), or HER-2 receptor, is one of the more aggressive forms of the disease. Tamoxifen and aromatase inhibitors are examples of endocrine (hormone) therapy that are likely to be effective for cancers that express the estrogen receptor (ER) and/or progesterone receptor (PR). certain oral medications, which are taken for five to ten years, cut the risk of recurrence of certain “hormone-positive” tumors in half. Although they are usually well tolerated, endocrine medications might cause menopausal symptoms.
Cancers that do not express ER or PR are “hormone receptor negative” and need to be treated with chemotherapy unless the cancer is very small. The chemotherapy regimens available today are very effective in reducing the chances of cancer spread or recurrence and are generally given as outpatient therapy. Chemotherapy for breast cancer generally does not require hospital admission in the absence of complications.
Breast cancers that independently overexpress a molecule called the HER-2/neu oncogene (HER-2 positive) are amenable to treatment with targeted biological agents such as trastuzumab. When targeted biological therapies are given, they are combined with chemotherapy to make them effective at killing cancer cells.
Radiotherapy plays a very important role in treating breast cancer. With early-stage breast cancers, radiation can prevent a woman having to undergo a mastectomy. With later stage cancers, radiotherapy can reduce cancer recurrence risk even when a mastectomy has been performed. For advanced stages of breast cancer, in some circumstances, radiation therapy may reduce the likelihood of dying of the disease.
The effectiveness of breast cancer therapies depends on the full course of treatment. Partial treatment is less likely to lead to a positive outcome.
Global impact
High-income countries saw a 40% decrease in age-standardized breast cancer mortality between the 1980s and 2020 (1), and those that have been successful in lowering breast cancer mortality have been able to do so at an annual rate of 2–4%. Strategies for improving breast cancer outcomes rely on strengthening the health system at the fundamental level to provide treatments that are already proven to be effective; these are also crucial for managing other cancers and other non-malignant noncommunicable diseases (NCDs). For instance, having trustworthy referral pathways from primary care facilities to district hospitals to dedicated cancer centers is one example.
The establishment of reliable referral pathways from primary care facilities to secondary hospitals to dedicated cancer centres is the same approach as is required for the management of cervical cancer, lung cancer, colorectal cancer and prostate cancer. To that end, breast cancer is a so-called index disease whereby pathways are created that can be followed for the management of other cancers.
WHO response
The objective of the WHO Global Breast Cancer Initiative (GBCI) is to reduce global breast cancer mortality by 2.5% per year, thereby averting 2.5 million breast cancer deaths globally between 2020 and 2040. Reducing global breast cancer mortality by 2.5% per year would avert 25% of breast cancer deaths by 2030 and 40% by 2040 among women under 70 years of age. The three pillars toward achieving these objectives are: health promotion for early detection; timely diagnosis; and comprehensive breast cancer management.
By providing public health education to improve awareness among women of the signs and symptoms of breast cancer and, together with their families, understand the importance of early detection and treatment, more women would consult medical practitioners when breast cancer is first suspected, and before any cancer present is advanced. This is possible even in the absence of mammographic screening that is impractical in many countries at the present time.
