Breast cancer, medically known as carcinoma of the breast, is the most common cancer among women in Hong Kong.
It originates from abnormal mutations in cells within breast tissue (such as ducts or lobules), leading to uncontrolled cell division and proliferation, ultimately forming a malignant tumour. If not detected early, cancer cells may spread to other parts of the body through the lymphatic system or bloodstream.

Understanding the causes of breast cancer and recognising early symptoms is the first line of defence in protecting breast health.

The OncoCare medical team is committed to providing accurate medical information to help you detect changes early and begin timely cancer management.

In 5-10% of cases, breast cancer is hereditary. The cancer is caused by specific gene mutations (changes) in the BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two) genes.² There are several other genes other than BRCA1 and BRCA2 that also help make up this percentage.

These genes can develop abnormally which may then be passed down through family generations, increasing the chance of breast (and ovarian) cancers.²

Breast cancer usually results from a combination of multiple risk factors. Understanding these can help assess your personal risk:

1. Heredity and Genetic Mutations

• Approximately 5% to 10% of breast cancer cases are related to inherited genetic mutations, most notably BRCA1 and BRCA2 genes.
• Women carrying these mutations have a significantly higher lifetime risk of developing breast and ovarian cancer compared to the general population.

2. High Levels of Estrogen

Estrogen stimulates the growth of breast cells. Prolonged exposure to estrogen may increase risk, including:

• Early menstruation (before age 12) or late menopause (after age 55)
• Never having given birth or having the first child after age 35
• Long‑term use of hormone replacement therapy (HRT) or certain oral contraceptives

3. Lifestyle and Environmental Factors

• Increasing age: Risk rises significantly with age, especially after 50
• Unhealthy lifestyle: Lack of regular exercise, overweight or obesity (especially after menopause), long‑term alcohol consumption and high‑fat diet
• Personal medical history: Previous breast cancer, ovarian cancer, or atypical ductal hyperplasia (ADH)

Many women mistakenly believe that “no lump means no cancer.” In reality, early breast cancer symptoms can be subtle and varied, and changes may occur before a lump becomes noticeable. Please pay attention to the following early signs:

Early detection is the most critical factor in improving survival and treatment outcomes.

If abnormalities are suspected, doctors will in general perform a Triple Assessment, which includes clinical examination, advanced imaging (such as 3D mammography), biopsy. This may be determined based on clinical needs and your condition.

Understanding Breast Cancer Staging

After diagnosis, breast cancer is classified from Stage 0 to Stage 4 based on tumour size, lymph node involvement and presence of distant metastasis (TNM system). This staging determines the next steps in treatment.

Breast cancer diagnosis involves a number of tests. You may undergo a mammogram, which takes an x-ray of your breast to check for signs of cancer; an ultrasound of the breast to identify tumorous masses and differentiate between benign and malignant tumours; an MRI, which determines the size and extent of the cancer; a blood test, to examine the breast cancer index; or a breast biopsy, which involves removing tissue from the tumour to examine.

Further tests may also be required, often to see if the cancer has spread beyond the breast, including a PET scan.

Moving Towards Personalised Treatment

Doctors will design an appropriate treatment plan based on cancer stage and receptor status.
Treatment options may include surgery, chemotherapy, targeted therapy, and immunotherapy. More information: Our breast cancer treatment | OncoCare.