What causes breast cancer?
Breast cancer like all cancers is an abnormal growth of cells which have the potential to spread to other parts of the body. Cancers are called malignant, and are different to benign growths which don’t have the ability to spread. Breast cancer is the most common non-skin cancer affecting women. In Australia about one in seven to one in eight women will get breast cancer. Fortunately because the treatments for breast cancer are very effective for many cases, the 5 year survival is over 90%. There is not one single cause for breast cancer, in most cases and often its cause is multifactorial.
Breast cancer risk factors:
1. Being female: this may sound a little obvious but it is important to note that male breast cancer does occur in about one in every 150 cases or so.
2. Age: as one gets older the risk of getting breast cancer is greater even beyond your 70s so that if you are healthy in this age bracket it’s still worth continuing with regular mammography and screening
3. Genetic’s and inherited genes: it’s important to realise that most breast cancers are not directly related to inheriting a gene and are sporadic meaning that they arise from many insults on our DNA finally resulting in cells growing out of control.
4. High levels of radiation exposure to the upper body (Mantle radiotherapy): this is becoming less common a cause as such radiation treatment for cancers including lymphoma has become more historical and not commonly used now. It’s important to note that low levels of radiation such as mammography do not cause an increase risk of breast cancer.
6. Menstrual and obstetric history: early onset of periods ( Menarche) and delayed menopause increase the risk of breast cancer. Having babies early in your reproductive life and breastfeeding are protective
7. Breast density: the higher the breast density, particularly in older women the greater the risk of developing breast cancer. Women with high breast density should consider adding Ultrasound to mammography for screening. MRI may also be useful in this group.
8. A past history of atypia on breast biopsy: this may increase the risk of developing breast cancer by 2 to 4 times or more depending on the type of change seen on histology.
9. Lifestyle factors: these would include alcohol consumption, obesity and prolonged hormone replacement therapy usage.
10. Vitamin D deficiency has been associated with an increased risk in breast cancer but this association is poorly understood. At BreastCare we do check vitamin D levels in patients presenting with breast cancer as there is some data to indicate an improved outcome if this deficiency is corrected.
Breast cancer diagnosis and types
Breast cancer may present as a symptom
- A lump
- Nipple discharge
- Nipple retraction
- Skin tethering (change in breast shape)
Commonly, early on, there may be no symptoms and breast cancer may be found on a mammogram or ultrasound as a mass or other abnormality. The diagnosis of breast cancer is usually confirmed on a needle biopsy. The most reliable needle biopsy is either a core or vacuum needle biopsy obtaining a core of tissue, however sometimes the diagnosis may be made on fine needle biopsy where cells are extracted, individually and in small groups, through a smaller needle.
The principle of diagnosing or excluding breast-cancer based on the examination, the imaging (including ultrasound and mammography) and with needle biopsy, is known as triple assessment and should be performed on women presenting with a breast symptom.
Types of breast cancer
- Tubular
- Medullary
- Mucinous
- Papillary
- Micropapillary
- Metaplastic (squamous cell, neuroendocrine)
Most breast cancers are invasive meaning that they have penetrated the wall of the duct or lobule.
Sometimes breast cancer may be picked up earlier, before it has broken through the wall all the duct and this is termed in situ cancer. In the milk duct this is called ductal carcinoma in situ (DCIS). Lobular carcinoma in situ (LCIS) is not regarded as carcinoma itself but more as a marker for higher risk of developing breast cancer later and not necessarily at the site of the LCIS.
The above types are based on what is seen under the microscope, however every cancer is subtly different and the treatment of breast cancer is based on other features including whether it is oestrogen sensitive, how fast it is growing and whether there is evidence of further spread to other areas like the lymph nodes. Therefore breast cancer treatment is individualised for each patient based on the type and features of their particular breast cancer.
