Breast Cancer: Causes, Types, and Modern Treatment

Breast cancer is one of the most common cancers globally, affecting millions each year. While it predominantly impacts women, men can also develop the disease, albeit less frequently. It arises when breast cells grow abnormally, often forming a lump or tumour. Advances in science have helped uncover the causes of breast cancer, paving the way for better prevention, early detection, and treatments.

What Causes Breast Cancer?

Breast cancer develops when changes (mutations) occur in the DNA of breast cells. These mutations disrupt the cell'snatural lifecycle, causing it to grow uncontrollably and, in some cases, invade nearby tissues or spread to other parts of the body. A range of biological, genetic, hormonal, and environmental factors can increase the risk of developing breast cancer.

  1. Genetic Mutations

Approximately 5-10% of breast cancer cases are inherited, caused by mutations in specific genes that increase susceptibility to the disease. The most well-known of these are the BRCA1 and BRCA2 genes. Normally, these genes repair damaged DNA, but when mutated, they significantly increase the risk of breast and ovarian cancers (NHS, 2023).

  • Women with BRCA mutations have up to a 70% lifetime risk of developing breast cancer.

  • Mutations in other genes, such as TP53 and PALB2, have also been linked to breast cancer.

  • Hormonal Factors

Hormones, particularly oestrogen and progesterone, play a critical role in breast cancer development. Oestrogen promotes the growth and division of breast cells, but prolonged exposure to high levels of this hormone can increase the risk of mutations. Factors contributing to prolonged hormonal exposure include:

  • Early menstruation (before the age of 12) or late menopause (after 55).

  • Use of Hormone Replacement Therapy (HRT): Increases oestrogen levels in the body.

  • Pregnancy history: Women who have their first child after the age of 30 or those who remain childless experience more menstrual cycles, thereby increasing cumulative oestrogen exposure (Cancer Research UK, 2023).

  • Age and Biological Changes: Breast cancer risk increases with age, as the body accumulates more genetic mutations over time. Most cases are diagnosed in women over 50 (NHS, 2023).

  • Lifestyle and Environmental Factors

  • Obesity: Fat tissue produces oestrogen, and excessive body fat, particularly after menopause, increases breast cancer risk.

  • Alcohol consumption: Even small amounts of alcohol can increase oestrogen levels and cause DNA damage.

  • Radiation exposure: High doses of radiation, especially during adolescence, can damage DNA and increase the risk of breast cancer.

Inflammation and Oxidative Stress

Chronic inflammation in breast tissue, whether due to infection or injury, can lead to DNA damage. Additionally, oxidative stress, caused by the accumulation of free radicals, has been linked to the development of breast cancer (World Cancer Research Fund, 2023).

Types of Breast Cancer

Breast cancer is not a single disease but a collection of types with varying behaviours and treatment approaches. The most common types include:

  1. Ductal Carcinoma In Situ (DCIS): A non-invasive type confined to the milk ducts.

  2. Invasive Ductal Carcinoma (IDC): Begins in the ducts and spreads to surrounding breast tissue; the most common form of breast cancer.

  3. Invasive Lobular Carcinoma (ILC): Arises in the milk-producing lobules and spreads to adjacent tissues.

  4. Triple-Negative Breast Cancer (TNBC): A fast-growing type that lacks hormone and HER2 receptors, making it harder to treat.

  5. Hormone Receptor-Positive Breast Cancer: Driven by oestrogen or progesterone, making hormone therapies effective.

  6. HER2-Positive Breast Cancer: Overexpresses the HER2 protein, leading to rapid growth but often responsive to targeted therapies.

How is Breast Cancer Treated?

Treatment for breast cancer is highly individualised, tailored to the type, stage, and patient’s overall health. Common treatments include:

  • Surgery

  • Lumpectomy (Breast-Conserving Surgery): Removes the tumour and a small margin of surrounding tissue.

  • Mastectomy: Removes one or both breasts, depending on the cancer’s extent.

  • Lymph Node Removal: Checks whether cancer has spread to the lymphatic system.

  • Radiotherapy: High-energy radiation is used to destroy any remaining cancer cells after surgery or shrink tumours before surgery. It reduces the risk of recurrence (NHS, 2023).

  • Chemotherapy: Uses drugs to kill fast-growing cancer cells. It can be administered before surgery (neoadjuvant chemotherapy) to shrink tumours or after surgery (adjuvant chemotherapy) to reduce recurrence risk.

  • Hormone Therapy: For hormone-sensitive cancers, treatments block the effects of oestrogen or lower hormone levels. Common drugs include tamoxifen and aromatase inhibitors.

  • Targeted Therapy: This focuses on specific features of cancer cells. For example:

  • HER2-Positive Breast Cancer: Treated with drugs like trastuzumab (Herceptin), which block HER2 receptors.

  • CDK4/6 Inhibitors: Used for some hormone receptor-positive cancers to slow tumour growth.

  • Immunotherapy

Boosts the immune system’s ability to fight cancer. This is particularly effective in certain cases of triple-negative breast cancer.

The Science of Hope

Breast cancer research has made significant strides, particularly in understanding the disease at a molecular level. New treatments, including gene therapies and precision medicine, are transforming care. For example, researchers are studying the BRCA1 and BRCA2 genes to develop preventative strategies for those at high risk (Cancer Research UK, 2023).

Conclusion

Breast cancer is a multifaceted disease influenced by genetics, hormones, and lifestyle. While not all cases can be prevented, understanding its causes and types empowers individuals to take proactive steps towards reducing their risk. Combined with advancements in science, early detection and effective treatments are helping millions of people live longer, healthier lives after a breast cancer diagnosis.

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