Breast Cancer
Breast cancer is one of the most common cancers in women, but it can also affect men. According to the American Cancer Society, 29% of new cancer diagnoses in 2016 were breast cancer (Jia et al., 2017). Breast cancer has been a rare disease until approximately 50 years ago, with the increase in incidences caused by many environmental and lifestyle factors and improved diagnostic screening (Fredslund & Bonefeld-Jørgensen, 2012).
The main types of breast cancer include the following:
Oestrogen receptor positive breast cancer means that the cancer cells respond to oestrogen hormone for growth. Progesterone positive breast cancers will respond and grow to the progesterone hormone. In a particular subtype of breast cancer, called "triple negative", the cancer cells are negative to oestrogen receptors, progesterone receptors, and the HER2 gene, which are normally found on breast cancer cells (Jia et al., 2017). The CIS and IBC types can also be responsive to oestrogen, progesterone or the HER2 gene (Martínez-Pérez et al., 2017).
Symptoms of breast cancer can vary, depending on where the cancer is in the breast, but can include a change in the shape of the breast, lumps felt in the breast, dimples on the breast, redness, unusual pain which doesn't go away, swollen lymph nodes, discharge from the nipple or a change to the nipple, or other symptoms. These symptoms may be caused from other conditions and may not be related to breast cancer (Cancer Australia, 2017).
The risk factors of breast cancer include the following:
The main types of breast cancer include the following:
- Carcinoma in situ (CIS) - is an early stage non-invasive breast cancer, and can be further categorised into confined Ductal or Lobular types, depending on whether it originates in the milk ducts or the milk glands of the breast respectively. DCIS is the most common type of non-invasive breast cancer (Osiecki, 2012, p352), and accounts for about 20% of all detected breast cancers. This category can be a precursor to developing into an invasive form in about 40% of cases if untreated (Martínez-Pérez et al., 2017).
- Invasive breast cancer (IBC) - this type of breast cancer can be further categorised into Invasive Ductal Carcinoma or Invasive Lobular Carcinoma, depending on where it originated. As the name suggests, the cancer has broken through its original site and can metastasise or spread to other parts of the body through the bloodstream or lymphatic system (Osiecki, 2012, p352).
- Inflammatory breast cancer - this is not a common type, accounting for only 1% of all breast cancers. This type makes the skin of the breast look inflamed, hot and dimpled, due to cancer cells blocking lymph vessels in the breast (Osiecki, 2012, p352).
Oestrogen receptor positive breast cancer means that the cancer cells respond to oestrogen hormone for growth. Progesterone positive breast cancers will respond and grow to the progesterone hormone. In a particular subtype of breast cancer, called "triple negative", the cancer cells are negative to oestrogen receptors, progesterone receptors, and the HER2 gene, which are normally found on breast cancer cells (Jia et al., 2017). The CIS and IBC types can also be responsive to oestrogen, progesterone or the HER2 gene (Martínez-Pérez et al., 2017).
Symptoms of breast cancer can vary, depending on where the cancer is in the breast, but can include a change in the shape of the breast, lumps felt in the breast, dimples on the breast, redness, unusual pain which doesn't go away, swollen lymph nodes, discharge from the nipple or a change to the nipple, or other symptoms. These symptoms may be caused from other conditions and may not be related to breast cancer (Cancer Australia, 2017).
The risk factors of breast cancer include the following:
- Age - most breast cancers occur in women over 50 years of age, and the risk increases with age (Osiecki, 2012, p353).
- Ethnicity - breast cancer occurs more in Caucasian women than African American or Asian women (Osiecki, 2012, p353).
- Diet – there is conflicting evidence that diets high in saturated fats influence breast cancer (Osiecki, 2012, p354). The association between dietary fats and cancer seems to depend on age, the type of cancer and its hormone responsiveness. A high ratio of omega-6 to omega-3 fats is linked to breast cancer. Increasing the intake of omega-3 fats and decreasing omega-6 reduces inflammation and the cancer risk (Bassett, Hodge, English, MacInnis & Giles, 2016).
- Infections - chronic infections such as from Epstein-Barr virus (EBV) or others can lead to breast cancer in some people, and often a more aggressive form (Glaser, Canchola, Keegan, Clarke, Longacre & Gulley, 2017).
- Smoking and alcohol – smoking and a high intake of alcohol can increase the risk of some types of breast cancer, particularly the hormone-sensitive types (Fredslund & Bonefeld-Jørgensen, 2012). Excessive alcohol increases oestrogen levels by affecting liver function (Osiecki, 2012, p352).
- Low vitamin D – having optimal vitamin D levels offers a protective effect against breast cancer, but low levels can increase the risk (Fredslund & Bonefeld-Jørgensen, 2012).
- Hormonal factors - an early menarche and late menopause, and therefore more menstrual cycles and the length of time exposed to oestrogen (Fredslund & Bonefeld-Jørgensen, 2012). In addition, an increased exposure to oestrogen from the body, medications (such as contraceptives), or environmental oestrogens and hormone disrupting chemicals, the higher the risk (Osiecki, 2012, p352).
- Environmental chemicals – many household, industrial and agricultural chemicals can increase oxidative stress, disrupt hormones and cause toxicity and menstrual disturbances. Such chemicals can also cause mutations in liver detoxification genes, and effecting detoxification of chemicals and hormones, which can lead to breast cancer (Fredslund & Bonefeld-Jørgensen, 2012).
- Increased weight and metabolic changes – fat stores produce increased oestrogen and other metabolic hormones, as well as inflammatory chemicals, which can contribute to the increased risk of breast cancer (Fredslund & Bonefeld-Jørgensen, 2012).
- Genetics – approximately 10% of all breast cancers are inherited, mainly due to mutations or damage to the BRCA1 and BRCA2 genes, and many others (Fredslund & Bonefeld-Jørgensen, 2012). However, you can have these genes and it doesn't mean that you will get breast cancer.
- Poor sleep quality - poor quality or quantity of sleep can increase the risk of breast cancers through several factors - by increasing oestrogen levels and having low melatonin (the sleep hormone) levels, and is especially a problem with people who are shift workers. Short sleep patterns increases inflammation, reduces immune system function, reduces DNA repairing, increases weight, and other metabolic disruptions. These factors may result in a more aggressive breast cancer (Soucise et al., 2017). Melatonin has been shown to reduce the risk of metastasis and reduce the toxic effects of anti-cancer drugs (Reiter et al., 2017).