Breast Cancer: Know About It But Don't Want to Greet It

Breast Cancer is an abnormality of breast cells that undergo division and can spread to other organs. Generally, it is believed that most breast cancers originate from cells located between the terminal ducts and the mammary glands, or some theories suggest that they may originate from stem cells in the ducts and mammary glands, which then transform into various types of breast cancer.

Are more people getting breast cancer than before?

Yes! In the past, breast cancer was the second most common cancer after cervical cancer, but in recent years breast cancer has become the number one cancer found in women and is expected to continue increasing. It is more common in urban areas than in rural areas, and more common in America and Europe than in Asia.

Breast cancer can be found in women under 20 years old, but it is very rare and becomes more common with increasing age.

Statistics show that breast cancer incidence starts to rise in women aged 35-39 and increases significantly at ages 40-44. Therefore, all women should undergo breast cancer screening with mammography ± ultrasound at age 40 or older, or earlier if there are other risk factors.

Can men get breast cancer?

Men can also get breast cancer, but the chance is about 100 times less than in women. However, by the time it is detected, it is often quite advanced because men have less breast tissue, so the tumor can quickly spread to the skin or chest wall.

Causes of breast cancer?

The causes of breast cancer involve multiple factors such as genetics, long-term hormone therapy after menopause. However, even if there is no direct family history of cancer and no hormone therapy has been received, there is still a chance of developing breast cancer due to other risk factors such as:

• Early menarche increases the risk of breast cancer. Late menarche reduces the risk by 5-10% per year because early menarche indicates that the ovaries produce female hormones that stimulate the breast earlier.
• Late menopause Each year of delayed menopause increases the risk by 3%. Conversely, women who experience early menopause or have both ovaries removed have a reduced risk (hysterectomy alone has no effect because the ovaries still produce hormones).
• Age at first childbirth Women who have their first child after age 35 have a 40-60% higher risk than those who have their first child at age 20. Therefore, early childbirth reduces breast cancer risk. Pregnancy temporarily increases breast cancer risk due to elevated female hormones stimulating breast cells to multiply, but after 10 years, it becomes protective in the long term as breast cells differentiate and become more resistant to carcinogens.
• Number of children Having multiple children reduces risk by 7% per additional child.
• Breastfeeding Prolonged breastfeeding has a protective effect, reducing breast cancer risk by about 4.3% for every year of breastfeeding. The more and longer breastfeeding occurs, the greater the protective effect, as breastfeeding delays ovarian function and promotes breast cell differentiation.
• Hormonal contraceptives Use increases risk by 24% while taking them, but risk decreases after stopping and returns to normal after more than 10 years. No correlation has been found between duration of contraceptive use and breast cancer risk.
• Hormone therapy for menopausal women Risk increases by 2.3% per year of hormone use and by 35% in women using hormones for more than 5 years. Risk returns to normal 5 years after stopping. Combined hormone therapy (estrogen with progestin) increases breast cancer risk more than estrogen alone.
• Body Mass Index (BMI) Obese postmenopausal women have increased risk. Women with BMI = 28 kg/m2 have about 26% higher risk than those with BMI <21 kg/m2 (no effect seen in premenopausal women). This is likely because after menopause, ovaries stop producing hormones, but fat cells produce female hormones, so higher BMI means higher hormone levels.
• Alcohol consumption Increases breast cancer risk. Risk increases with amount consumed, e.g., drinking 35-44 g/day increases risk by 32%, drinking 45 g/day or more increases risk by 46% compared to non-drinkers, or risk increases 7% per 10 g/day of alcohol.
• Regular exercise May help reduce breast cancer risk by 10-50%.
• Soy foods May have a protective effect. Countries with high soy consumption, such as Japan and China, have relatively low breast cancer rates compared to other ethnicities. Soy contains isoflavones, which are similar to female hormones but much weaker, potentially reducing the effect of female hormones in premenopausal women. Women consuming more than 20 mg/day of isoflavones have a 29% lower risk compared to those consuming ≤ 5 mg/day.
• High-fat diet May increase breast cancer risk by 10-50%. Studies where people reduced fat intake and increased fruits and vegetables over 8 years showed a 9% risk reduction. High-fat diets may increase BMI or include charred red meat, which may be more responsible for increased risk.
• Radiation exposure Increases breast cancer risk depending on dose and age at exposure. Risk is higher if exposed before age 20 and lower if exposed after age 40. Patients with Hodgkin’s lymphoma receiving more than 40 Gy radiation have an 8-fold increased risk.
• Genetics Having a first-degree relative (mother, sister) with breast cancer doubles the risk. Risk increases further if more than one relative is affected, if relatives had early-onset breast cancer, bilateral breast cancer, both breast and ovarian cancer, or if a male relative has breast cancer.
• Ethnicity America, Europe, and Africa have higher risk than Asia.
• Genes Several genes affect breast cancer risk, such as BRCA1 and BRCA2, which are breast cancer suppressor genes. Mutations in these genes increase risk more than 10 times. BRCA1 mutations carry a 50-90% chance of breast cancer, BRCA2 mutations about 50%. Other genes also exist but with lower percentages.
• Dense breast tissue Seen on mammograms (Mammographic density), breasts with high density have 2-6 times higher risk. Hormone therapy for menopausal women can increase breast density.
• History of breast tumors Some tumors do not increase breast cancer risk, such as fibroadenoma and breast cysts. Some tumors slightly increase risk (1.5-1.9 times), such as adenosis and intraductal papilloma. Others increase risk by 3-5 times, such as atypical lobular hyperplasia (ALH) and atypical ductal hyperplasia (ADH). Some tumors (DCIS) are considered pre-invasive cancer, and some (LCIS) indicate potential future cancer risk.
• History of breast disease If there is a history of ADH, ALH, LCIS, DCIS, or previous breast cancer on one side, regular follow-up is necessary.

Assoc. Prof. Dr. Kamonrat Piboon
Specialist in Breast Surgical Oncology
Rak Breast Center, Phyathai 1 Hospital