Breast cancer is among the most common causes of cancer among women and among the main cause of cancer related death in the world. Breast cancer is named after the organ where cancer originated, though it may spread to other parts of the body surrounding the breast. Breast cancer affects both men and women, though it is more common to women than men. Women can get breast cancer at any age, though it is more common among older women from age 50 to 74. Women of this age are thus needed to take breast screen after every two years to enhance its early diagnosis and effective treatment.
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Breast Cancer Types/ Forms
Breast cancers can be groups as non-invasive and invasive. Non-invasive breast cancer refers to a form of cancer where the cancer cells are limited to the ducts and hence they do not invade surrounding breast connective and fatty tissues. There are two main forms of non-invasive breast cancers which include ductal carcinoma in situ (DCIS) which is the most popular form of non-invasive breast cancer, accounting for about 90% of non-invasive cancer cases in the world. The other form is lobular carcinoma in situ (LCIS). Invasive breast cancer cells on the other hand break through the lobular wall and duct and attack the surrounding breast connective and fatty tissues.
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The most common form of invasive cancer is infiltrating ductal carcinoma (IDC) that starts in breast milk ducts and penetrates the duct walls invading breast fatty tissues and other probable areas of the body. This cancer accounts for 80% all cases of diagnosed breast cancer. Another form of invasive breast cancer is infiltrating lobular carcinoma which starts at the milk glands and metastasizes to other body areas. This accounts to 10-15% of all cases of breast cancer. The least frequently occurring forms of breast cancers include medullary carcinoma which is a form of invasive cancer, mutinous carcinoma which a rare kind of breast cancer created by mucus-producing cancer cell, and tubular carcinoma which is an invasive breast cancer. Others include inflammatory breast cancer which starts as inflamed breast with thick ridges or dimples initiated by cancer cells blocking lymph channels or vessels over the breast skin. There is also the nipple paget’s disease which is a rear kind of breast cancer that starts at the milk duct and spreads to areola and nipple skin, and finally phylloides tumor that can be either malignant or benign. Phylloides tumors generate in the breast connective tissues and might be treated through surgical removal. This form of cancer is quite rare.
Breast cancer affects both men and women, though the cancer is more common to women and quite rare in men. Breast cancer is the most popular reason of cancer death among women in about 140 out of 184 countries in the world. Breast cancer is the most often diagnosed form of cancer among women, and it currently represents a quarter of all cancers in women. Breast cancer is the main reason for women death in ages 40 to 59. Cases of breast cancer are high in developing countries compared to developed countries, but still remain the leading cause of women death in both situations. The women lifetime risk of getting invasive breast cancer is 12.6%, and one out of eight women in the United States will develop breast cancer at a certain stage in her lifetime.
The risk factors for breast cancer include environmental factors which include being exposed to ionizing radiation as a result of therapeutic procedures, medical diagnostic procedures, gadgets use or nuclear war increase breast cancer development risks. Another risk factor is sociobiological factors that include age and gender. Breast cancer is more common to women aged 50 and above. Thus being a female and at older age increases risk of developing breast cancer. Nutrition is another factor where by high fats, red meat and caffeine intake increases breast cancer developing risks, while high consumption of vegetables and fruits might reduce breast cancer development risks. Other factors include physiological factors where moderate physical exercise or activities reduce breast cancer risks. Genetic factor where 5 of 6% of occurring cases of cancers are regarded to be hereditary and also family risk factor where cancer history in the family create a possibility of cancer development among other family members. Alcohol is also said to increase breast cancer risks. Individual history of breast cancer increase risks of developing second case of breast cancer. Hormonal history of a woman is also a risk factor where risk increase with number of individual menstrual cycle in a lifetime2. Other risk factors include poor immune system, use of oral contraceptives and hormone replacement therapy, exposure to carcinogens, use of tobacco, the breast pathogenic diseases, chronic breast inflammation, conducting induced abortion, not breastfeeding or breastfeeding for a shorter period, and number of life birth where the more the life birth are the lower the risk of developing breast cancer.
Breast cancer pathobiology is complex compared to other cancers. Mammary disseminated tumor cells have the ability to remain dormant for a number of years. Nevertheless, the systematic growth of tumor resumes eventually, resulting to clinically recurrent disease. Breast cancer possibly includes over 20 subsets of tumor that affect the disease course. Such subsets of tumor are typified by specific immunological, hormonal and biochemical features. Subclinical metastasis exists already in most patients during diagnosis time. Cancer cells hematogenous dissemination probably starts after doubling of 20 tumors.
Molecular Basis of the Cancer
The molecular mechanisms fundamental to the breast cancer development in general and associated breast carcinogenesis in specific are not well understood. It breast cancer initiation is generally believed to emanate from aberrant programmed apoptosis or death of cell or/and uncontrolled proliferation of cell due to collective genetic damages which result to changes of genetics that yield to proto activation which implies inactivation and oncogenes of tumor suppressor genes. Genetic changes in turn can be attained as somatic mutations or be inherited as mutation of gremlin. The somatic mutations may happen due to exposure to biological, chemical or physical environmental carcinogens.
The breast cancer clinical manifestation include swelling or thickening of some breast parts, new lump underarm or in the breast, and dimpling or irritation of breast skin. Others include flaky skin or redness of the breast or nipple area, pain in the area of the nipple or nipple pulling in. Other signs include other nipple discharge than milk which include blood, change in the breast shape or size or breast pain. Other than visible changes, the presence of breast cancer can be determined by conducting various tests which include mammogram screening, breast biopsy, magnetic resonance imaging (MRI), molecular breast imaging, and blood-based essay.
Biomarkers and Cytogenetic Laboratory Features
Biomaker analysis in breast cancer is a routine practice. It initially focused on hormone receptor expression testing to guide tamoxifen therapy. It then advanced to human epidermal growth factor receptor 2 (HER 2) target treatment. Biomaker testing has also been integrated in genetic platform dsigned to hhelp prognosis and chemotherapy response prediction in patient with hormone receptors tumor but without lymph-node metastases.
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Other biomarker tests in breast cancer include ki-67 that determines breast cancer proliferative activity, and progesterone and estrogen receptors which predict hormone therapy response (Colomer et al., 2017). Complex karyotypes have been related with unfavorable breast cancer result. Modern methods that include relative genomic hybridization (CGH) and cDNA microarrays have additionally identified complex defects of genetics related with adverse prognosis.
Metastasis is mechanically described as tumor cells migration from the primary tumor, subsequent by extravasation, survival, intravasation of circulatory system and advanced colonization of a detached site. Tumor cells thus spread extensively through the body, though only grow in supportive location. Breast cancer metastasis is also denoted by pathways redundancy that mediates its component steps or process. Genes enhancing flourishing of breast cancer metastasis include IDI, ERBB2, MET, CTNNBU, SNAI2, KRAS, SNAI1, PI3KCA, TWIST1, EGFR and MMYC. Metastasis complicates the cancer treatment process due to its innate or acquired resistance to therapies. In breast cancer metastasis occurs at the last stages of the cancer and is regarded as the leading cause of death among breast cancer patients.
Breast cancer can either be in situ or not invasive or invasive. In situ is the first stage of breast cancer and it is denoted by stage O. From there the cancer can be in stage I where the tumor diameter is about 2 cm and is confined within the breast. Stage IIA the tumor diameter is about 2cm and has spread to not more than three armpit lymph nodes. Stage IIB tumor diameter is less than 2 inches and has spread to not more than three armpit lymph nodes or the tumor diameter is more than 2 inches though still confined in the breast. Stage IIIA the tumor diameter is about 2 inches and has spread to not more than nine armpit lymph nodes. Stage IIIB the tumor has spread to the skin or chest wall or initiated breast inflammation, or has spread to 10 and above armpit lymph nodes. Stage IIIC, The tumor has reached lymph nodes above or below collar bone or it has enlarged in one lymph node to the same size as the tumor in the breast.
Women at high risk of getting breast cancer who include women aged between 50 and 75 years should have mammogram screening once per every two years. Women at all ages are also encouraged to engage in physical activities, check on their weight, eat healthy by avoiding fats, caffeine and red meat and increasing vegetables and fruits in their diet. Women are also encouraged to avoid oral contraceptive and hormonal therapies, to consider breastfeeding their children for long and to minimize exposure to carcinogens.
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Breast cancer can be treated using various methods based on the stage of development. Surgery may be done to remove the tumor or the entire breast and surrounding tissues based on the level of development. Radiation therapy can also be used where high X-ray energy or other forms of radiation are used to suppress the growth or kill cancer cells. Chemotherapy may also be used where drugs are used to stop cancer cells growth, either through killing them or preventing their division. Hormonal therapy may also be used to block hormones actions or remove them and stop growth of cancer cells. Target therapy may also be applied where drugs are applied to attack and identify particular cancer cells without damaging normal cells.
Breast cancer is the leading cause of malignancy death among women. Individual survival rate depend on the type of breast cancer on is suffering from; invasive or non-invasive, where those diagnosed with non-invasive or in situ cancer have a higher survival rate. Metastasis is the leading cause of breast cancer death, thus those diagnosed by cancer at its advance stages have lower chances of survival; mostly less than 3 years. However, some may survive with the tumor for over 10 years when in situ. The survival rate decrease with young age diagnosis; women below 40 years have higher death risk than women diagnose at older age. Early diagnosis; at early cancer stage increases chances of survival, while late diagnosis reduces survival rate. In addition, survival rate of women with BRCA2 mutation is lower compared to those without BRCA2 mutation.
Current/ Future Research
A lot has been done in trying to understand breast cancer. There has been research on the main risk factors and how to reduce them, different types of breast cancer and how they manifest themselves, best form of treatment, cancer stages and the best treatment based on the stage among other things. However, there is little understanding on the molecular basis of the breast cancer which is said to be considerably complex. Understanding this may play a great role in treating and preventing breast cancer and hence this topic needs to be given extra consideration in future research.