Today, breast cancer is the most common disease affecting women worldwide. Last few years have seen a steady rise in the cases of breast cancers. In fact, female breast cancer incidence is 100% higher than that of the male breast cancer. Breast cancer is the second leading cause of death in women.
What are the Major Causes of cancer
Use of Pharmaceuticals and Reproductive factors: Use of estrogen-progesterone contraceptives, diethylstilbestrol can cause breast cancer. Prolonged hormone replacement therapy in women increases the risk of breast cancer in females. It has been clearly demonstrated that administration of estrogen-progestin and estrogen alone as a hormone replacement therapy can stimulate the growth of overt breast tumors in women. Early onset of menarche, late age at menopause, nulliparous women, and 30 years or above of age at first pregnancy are all known to be consistently associated with the increased risk of breast cancer.
Genetic factors: Family history of breast cancer raises the chances of developing breast cancer, but other factors which play significant role in this case are generational distance between the relatives, the age of the woman when the cancer was detected and the number of women affected with breast cancer. Also mutations in the genes like BRCA1, BRCA2, TP53, PTEN, STK11, and CDH1 are also identified as risk factors for causing breast cancer.
Lifestyle factors: It has been stated in research studies that the major causes of cancer are due to life course exposures to smoking, overweight and inactivity. Stress has been cited as one of the main factors causing breast cancer in women. Stress associated with work place, personal life and other relationship factors has contributed towards the development of stress in women. Tobacco smoking is also associated with breast cancer. Alcohol has also been considered to be carcinogenic for breast.
Occupational factors: Shift jobs disrupt the circadian rhythm which gives rise to breast cancer. The main occupational category in this type of causative factor is nurses, marine telephone operators and female flight attendants. Exposure to ethylene oxide which is used in the sterilization of medical equipment and synthesis of some chemicals out those who work in proximity to ethylene oxide at a risk of breast cancer. Another occupational factor likely to cause breast cancer are exposure to solvents, manufacturing of chemicals, and other solvents, service industry like health care industry, military personnel, journalists, physicians, dentists, administrators, artists, Laboratory technicians, telephone operators, leather and fur producers, glass manufacturing workers, inspectors, analysts, teachers, librarian and counselors.
Environmental factors: The presence of environmental endocrine disrupting chemicals (EDC’s) including pesticides and chemicals such as Bisphenol A has shown definite carcinogenic properties. Over more than 100 industrial wastes have been known to cause cancer. Researchers have reported that exposure to ionizing radiation is one of the environmental risk factors for causing breast cancer.
Pathology of breast cancerThe cancerous tissue shows four major types of abnormality:
· An increased number of cells than found in a normal tissue.
· An increased size of the cell than normal.
· A high ratio of nuclear to cytoplasm
· A higher proliferation rate or metastasis.
The cells may be present in an abnormal location such as invading the basement membrane or moving away from their site of origin to other places in the body. There is a marked dedifferentiation in the cancer cells. The tumor also secretes certain proteins into the circulation which are referred to as tumor markers which reflect the stage of the cancer.
The oncogenes found in the pathogenesis of breast cancer development are genes for growth factors (such as IGF), genes for EGF receptors (such as c-erb B), c-src and c-ras etc and the prevalent tumor markers in case of breast cancer are reported to carcinoembryonic antigen (CEA) and Prostate-specific antigen in some cases of breast cancer. Gene mutations in genes like BRCA1 and BRCA2 are also strongly associated with the pathology of the cancer cell.
Management and treatment of breast cancerFor the treatment of breast cancer, patients are treated with a combination of radical local therapy and systemic anticancer therapy. If there is any scope of breast conservation and is demanded by the patient, surgical excision is performed if it can remove all the disease. In pre- invasive cases complete mastectomy may be needed. It has been found that if the size of the tumor is too large compared with the size of the breast, systemic anti –cancer therapy is given prior to surgery which reduces the need for mastectomy to quite an extent. Loco regional radiotherapy has been done for successful breast conservation. During the treatment all the women should be considered for adjuvant systemic therapy inclusive of hormonal or chemotherapy or both. In case of very low risk tumors, adjuvant therapy may not be needed.
The treatment depends on the diagnosis, multidisciplinary assessment and a combination of local and systemic therapies. There are many types of treatment available for breast cancer; some are standard while some are still in the clinical trials stage. Majorly there are 6 types of treatments for breast cancer:
SurgeryThere are three surgical options which exist for the treatment of breast cancer. These are:
· Breast conserving surgery (BCS)
· Mastectomy with reconstruction
· Mastectomy alone
Radiation therapyHigh energy X rays or other radiations are used to kill the cancerous cells or prevent their further growth. Radiation therapy is given post mastectomy and reconstruction of the breast is carried out after that.
ChemotherapyThe major cytotoxic drug classes which are used in the treatment of breast cancer are:
· Alkylating agents such as bleomycin, mitomycin
· Antibiotics like methotrexate, 5-flurouracil,
· Antimetabolites (topoisomerase inhibitors) such as doxorubicin, epirubicin
· Mitotic spindle poisons like vinorelbine
· Vinca alkaloids such as docitaxel, paclitaxel
Most of the chemotherapeutic agents used in the treatment of cancer show severe adverse reactions which require supportive care and therapeutic intervention.
Hormone therapy of breast cancer involves removal of hormones or inhibiting their actions to prevent cancer. Ovarian ablation to stop the release of estrogen, use of tamoxifen is common in early stages of breast cancer or in metastases. Treatment with an aromatase inhibitor which prevents the conversion of androgen to estrogen is also done. The basic hormonal interventions include surgical adrenalectomy as a hormone ablative treatment for postmenopausal women, surgical hypophysectomy, and hormonal additive therapies such as the use of androgens, estrogens, progestin and glucocorticoids.
Targeted therapyMolecular biology has allowed blocking the pathways involved in the development of cancer. Targeted therapy is that treatment where cancerous cells are specifically targeted and it does not affect the normal cells. Monoclonal antibodies and tyrosine kinase inhibitors are two types of therapies which are prevalently used in the treatment of breast cancer.
High dose chemotherapy with stem cell transplantThis is a relatively new strategy in treatment of cancer where high doses of chemotherapeutics are given and along with it stem cells are replaced in the body. The stem cells are taken from the bone marrow of the patient or from a donor. The reinfused stem cells restore the blood cells of the body.
Outcome of breast cancer treatment
Research studies involving studies on survivors of breast cancer have put forth the fact that those females who have undergone chemotherapy as an adjunct therapy for the treatment of breast cancer have shown poorer outcomes. There was noted physical and psychosocial function improvement immediately after the treatment of breast cancer independent of recent adjuvant chemotherapy. Those women survivors who have been given adjunct chemotherapy for breast cancer treatment have noticeably experienced more severe, painful and debilitating physical outcomes which need to be effectively managed as part of cancer care.
Preventive measuresPrevention of cancer can be very well related to being the key to preventing number of deaths occurring due to breast cancer.
The most significant and obvious route to Breast cancer prevention is the knowledge of cancer. Knowledge of cancer may lead to suitable modifications and changes in the lifestyle of people which can prevent the development of cancer in them. Many studies have reported that there is a greater risk of development of breast cancer in women with a prolonged exposure to estrogen. Premature menopause can substantially reduce the risk of development of breast cancer. Therapeutic intervention such as the use of tamoxifen has also brought down the risk of development of breast cancer.
Another important point is the early diagnosis of asymptomatic cancer which can prevent mortality due to breast cancer.
The prevalence of breast cancer in women is of high concern and lifestyle changes and regular screening are highly recommended for the prevention of breast cancer or for an early diagnosis. Adjuvant therapy of cancer is only taken in medium and high risk tumors and the benefits of the different therapies should always be weighed against their advantages and disadvantages in the patient. Adequate information on breast cancer and regular personal screening of breasts should also be promoted.
Suggested ReadingBreast Cancer Treatment (PDQ®). (2013, 05 04). Retrieved from National Cancer Institute: http://www.cancer.gov/cancertopics/p.../Patient/page5
Cameron, D., & Howard, G. (2010). Oncology. In N. R. Colledge, B. R. Walker, & S. H. Ralston, Davidson's Principle and Practice of Medicine (pp. 253-272). Edinburgh: Elsevier.
Howell, A., & Evans, G. D. (2011). Hormone Replacement Therapy and Breast Cancer. Clinical Cancer Prevention Recent Results in Cancer Research, 115-124.
Rang, H. P., Dale, M. M., Ritter, J. M., Flower, R. J., & Henderson, G. (2012). Rang and Dale's Pharmacology. London: Elsevier.
Weiderpass, E., MEO, M., & Vainio, H. (2011). Risk Factors for Breast Cancer,Including Occupational Exposures. Safety and Health at Work (SH@W), 1-8.