Breast Cancer

Breast cancer is the abnormalities of breast tissue cells through mutation, uncontrolled proliferation and division. Tumors can be benign, but cancerous tumors are malignant. The exact cause of cancer is unknown, whereas both men and women have the chance to suffer from breast cancer. According to World Health Organization statistics, there are approx. 10% of the cancer cases belong to breast cancer. In the past 20 years, breast cancer among women has a rising trend in Hong Kong. Advancing age is a high risk factor for cancer, the average age of patients was 54 years old. But in recent years, there is significant increase in breast cancer diagnosed among young women aged 30 to 40. The youngest patient in Hong Kong is less than 20 years old.

According to the statistics of Hospital Authority’s Hong Kong Cancer Registry in 2014:

• In 2012, there were over 3,500 newly registered cases of breast cancer among women in Hong Kong, ranking first
• One in every 17 people on average had the chance to develop cancer
• 10 new registered cases on daily average were diagnosed as breast cancer
• Per 100,00 of the population, 91.7 were diagnosed and 15.7 died from breast cancer
• In 2012, breast cancer caused the death of 601 people, accounting for 11.1% of the cancer mortality rate, becoming number three killer of the female’s cancer mortality rate

Breast cancer can be caused by many factors, family history is thought to play a major role, as about 25% of the patients have a cancer hereditary family history. Eating and living habits are also crucial factor, the causes of common cancers nowadays are closely related with consumption of high-calorie food and emotional stress.

Breast cancer risk factors

• Age (the higher the risk)
• Obesity, overweight or long-term consumption of food high in animal fat
• Family history of breast cancer, especially mother or sister
• Women who began their periods before age 12
• Menopause after age 55
• Have never given birth, or have given first birth after the age of 35
• Never breastfed before
• Alcohol, smoking, lack of exercise
• Who have received chest radiation therapy
• Long-term exposure to radiation, long-term use of contraceptives or hormone supplement
• Long-term exposure to stress

Early symptoms of breast cancer include

• Breast lumps
• Breast changes shape, partially inverted nipple or skin
• Changes in nipple skin, swelling, ulceration, skin thickening or red scaly patches rash
• Abnormal nipple discharge or bleeding
• Swollen glands (lymph nodes) or lumps on armpits and neck
• Wounds on breast are difficult to heal
• Persistent or unusual pain (rarely seen)

According to histological classification of breast cancer, it is classified into “non-invasive breast cancer” (Carcinoma in situ) and “invasive cancer” (Invasive carcinoma / Carcinoma), the difference is that whether the basement membrane is still complete.

Diagnosis of breast cancer

The following method can be used to diagnose breast cancer usually
1. X-ray examination of the breast (Mammogram)
2. Ultrasound scan

If discovered breast lumps, doctors will extract tissues according to the situation with the following method:

• Fine Needle Aspiration: use thin needle to extract a sample of cells from the breast, just like drawing blood, its simple and fast.
• Needle biopsy: use slightly thicker needle to extract sample, patients require local anesthesia, the accuracy is higher than the thin needle.
• Excision biopsy: after general or local anesthesia, the entire abnormal lumps are removed for testing.

Classification and stage of breast cancer

Medical field classify cancer by the types of cancer and tumor-node-metastasis staging system (TNM). Today the factors that influence the recurrence are identified, enabled an even more detail classification, such as HER-2 breast cancer, triple-negative breast cancer (ER, PR, HER-2 are negatives) and high Ki-67 level breast cancer. Detail classification help grasp the characteristics of different cancer and apply suitable remedy, avoiding future recurrence.

Non-invasive breast cancer: with complete basement membrane, theoretically cancer cells do not spread, and it is generally not fatal if treated timely. However, it might deteriorate into invasive cancer.
Invasive breast cancer: cancer cells break through the basement membrane, invade the lymphatic system, spread to the blood vessels, bone marrow and even transferred to other organs such as the heart, liver, kidney etc., could be fatal.

Ductal carcinoma in situ (DCIS) is a non-invasive breast cancer, theoretically do not spread, should be treated timely to avoid deterioration.

If the tumor is less than 2cm, with no signs of axillary lymph nodes metastasis, the 5-year survival rate is 85%.

If the tumor is larger than 2cm, with signs of axillary lymph nodes metastasis, the 5-year survival rate is 70%.

If the tumor size has reached 5cm or more, in general it has affected the lymph nodes but have not yet spread to other parts of the body. The 5-year survival rate has remained 50%.

Regardless of the tumor size, lymph nodes have been affected, the cancer cells have spread to other body organs. The 5-year survival rate is only 15% left.

When breast cancer spread to other parts, it can cause life-threatening complications. Women should maintain self-examination, and seek medical attention immediately when in doubt.

Common types of cancer treatment

• Targeted Therapy
  Uses drugs to interfere with cancer cell growth and progression, when the antibodies enter the body, they will automatically look for antigens, identify cancer cells and notify the immune system to destroy them. (This method is only suitable for patients identified with HER-2 tumors, so early detection of breast cancer is important.)
• Surgical Resection
  • Lumpectomy: removal of the lumps and a small portion of surrounding tissues in the breast
  • Mastectomy: If the breast tumor is large and different parts of the breast are diagnosed with cancer cells which surrounded a large area near the ductal carcinoma in situ, mastectomy is required. Mastectomy is the removal of the entire breast tissue (including the skin and nipple), if the cancer cells spread to axillary lymph, removal of the breast and nearby lymph nodes is required, and even the chest wall muscle.
    *Women who did mastectomy can also have breast reconstruction surgery at the same time, or choose to rebuild in the future instead.
• Chemotherapy
  After the surgery, patient can undergo chemotherapy as adjuvant therapy. Chemotherapy uses anti-cancer drug (cytotoxic) to destroy cancer cells and reduce the chance of a recurrence.
• Hormone Therapy
  Hormone therapy uses anti-estrogen drugs to slow or prevent the growth of breast cancer cells. The efficacy depends on the response of the cancer cells to the hormones. Hormone therapy may also interfere the contraceptive effectiveness.
• Radiotherapy
  Radiotherapy is divided in vitro and in vivo, it uses high energy X-rays to destroy cancer tissues while minimizing the damage on normal cells. Radiotherapy is often used after breast cancer surgery, but sometimes also used before surgery, or even replacing surgery. The goal is to ensure the elimination of residual cancer cells. However, if the axillary lymph nodes are removed, radiotherapy is not suitable.