The trend of examining the chromosomal background of the diseases was set within the progressive studies of DNA structure. It was a part of the scientific advances at the time and seemed like a rational track of development. The importance of chromosomal analysis for cancer treatment and monitoring nowadays can hardly be underestimated, yet there are both theoretical and practical dimensions of this disease that remain understudied. In this paper, the chromosomal analysis of breast cancer will be assessed, and the causes of the disorder will be detailed. Apart from that, we will address the issue of a single gene and complex inheritance, as well as the gene mutation, how it occurs, and if the disease can be acquired or inherited.
Chromosomal analysis
Chromosomal analysis is considered to be an essential part of modern clinical medicine. This procedure allows identifying the abnormalities that are recognized in many forms of cancer nowadays (Vance, 2020). For breast cancer, it has even greater importance, as the experiments show that none of the breast tumors are cytogenetically normal, and most of them have abnormal karyotypes or clonal marker chromosomes (Vance, 2020). Besides, this procedure is applied in the course of treatment in order to monitor patients’ progress (Nussbaum et al., 2016). The process usually involves short-term cell culture, hypotonic treatment, division in metaphase, and cell suspension (Vance, 2020). The chromosome complement is identified by microscopic analysis, and malignant growth is determined, depending on the cells’ origin (Vance, 2020). Detection of a certain chromosome count allows making a prognosis, while the detection of an abnormality helps classify the type of cancer and develop the course of its treatment (Vance, 2020). While there still is a gap between cytogenetic analysis and molecular diagnosis, more techniques emerge in between, helping bridge it and invoke progress in cancer treatment (Vance, 2020). Thus, the opportunities given by chromosomal analysis are multiplying, increasing its importance for the field.
Causes of the disorder
As breast cancer represents a group of diseases, its types and causes also vary. It is known that breasts are made of a variety of tissues, and those include lobes, ducts, glands, lobules, lymph nodes and fatty tissue (“Cancer Treatment Centers of America,” n.d.). Cancer develops when cells mutate and start growing abnormally, leading to the formation of the tumor (“Cancer Treatment Centers of America,” n.d.). With breast cancer, most of the tumors form in milk ducts and about 10% – in the lobes or glands (“Cancer Treatment Centers of America,” n.d.). There are five clusters of risk factors for breast cancer development. General risks include aging – women over 60 are most likely to be diagnosed with breast cancer, and gender – risks of getting it for women are 100 times higher compared to men (“Cancer Treatment Centers of America,” n.d.). Genetics and family history also displays an important role – having a close relative (mother, sister or daughter) diagnosed doubles the chances, and inherited genetic mutations also increase the probability (“Cancer Treatment Centers of America,” n.d.). Besides, obesity, lack of children, extended menstrual history, high breast density, and structure changes are among the possible drivers (“Cancer Treatment Centers of America,” n.d.). Life habits such as heavy drinking, unhealthy diet, and lack of physical activity have an undoubted influence (“American Cancer Society,” n.d.). Finally, breast cancer might be caused by exposure to radiation, diethylstilbestrol (a drug given to women for miscarriage prevention until the 1970s), combined hormone therapy and birth control medication (“American Cancer Society,” n.d.). Overall, breast cancer can be caused by unhealthy lifestyle choices, biological peculiarities, exposure to severe treatment, and familial factors.
Origin of the disorder
There are several theories on the origins of cancer. Mutation theory is the most accepted one, but the existing nowadays experimental data questions its validity (Hanselmann & Welter, 2016). While mutations are regarded as the leading cause of breast cancer, normal tissues often demonstrate genetic changes in cancer-initiating and -driving genes (Hanselmann & Welter, 2016). Another theory suggests that the origin is in a chromosomal imbalance in aneuploidy (Hanselmann & Welter, 2016). However, later on, it was discovered that not every cell in a tumor shows chromosomal aberrations, and that this theory did not provide any explanation for the mitochondrial and nucleus transfer experiments (Hanselmann & Welter, 2016). The theory of mitochondrial dysfunction seemed to ignore that those are not the initial step in hereditary cancer and could not explain the development of cancer by substances directly disrupting mitotic spindle aperture (Hanselmann & Welter, 2016). Finally, the theory of environment and matter examined how micro-environmental changes could induce cancer, but also appeared to ignore the fact that in hereditary cancers, those changes were not representing the first step (Hanselmann & Welter, 2016). Currently, theories of cancer origins offer a change from a biologically mechanistic process, stating that the biochemical, physical, biodynamic sides of it are worthy of consideration (Hanselmann & Welter, 2016). This paradigm change in theoretical approaches might contribute to a better understanding of treatment courses.
As for the inheritance issue, the familial inheritance of cancer does not fit a clear pattern. For breast cancer, the genetic contribution is higher than for others, but its occurrence also depends on the environment, age, and gender (Nussbaum et al., 2016). It is most likely that the disorder is complex and is caused by both genetic and environmental drivers (Nussbaum et al., 2016). The epidemiological data existing nowadays is not providing sufficient evidence for any firm conclusions regarding the extent of inherited variants and familial tendencies for most of the types of cancer (Nussbaum et al., 2016). Therefore, the consensus stands that the complexity of factors influences the development of the disease.
Gene mutation and inheritance of the disease
It was discovered that some gene mutations could cause the progression of breast cancer. These mutations happen in driver genes – those most exposed to mutations (Rasnick, 2016). It is considered that most of the driver genes are already known, but less abundant of them will most probably be added later on (Nussbaum et al., 2016). The spectrum of gene mutations in cancer is massive – a small insertion or deletion in a driver gene, especially combined with an environmental agent, for example, carcinogens from cigarette smoke can start the oncogenic development (Rasnick, 2016). In the case of breast cancer, these genes are BRCA1 and BRCA1, they produce tumor suppressor proteins and help repair damaged DNA at different stages (“Cancer Treatment Centers of America,” n.d.). When they undergo a mutation, these genes might even begin to stimulate the progression of the tumor (“Cancer Treatment Centers of America,” n.d.). These mutations are inherited and increase one’s chances of getting breast cancer by five times (“Cancer Treatment Centers of America,” n.d.). Genetic testing reveals if there are mutations, and regular screenings also represent the way to handle the risks in families with breast cancer cases (“Cancer Treatment Centers of America,” n.d.). Even though cancer is not always hereditary, it is regarded as a genetic disease. There are various gene mutations and hereditary causes that can increase one’s chances of getting cancer, and sometimes, the progression is provoked by environmental agents.
References
American Cancer Society. (n.d.). Web.
Cancer Treatment Centers of America. (n.d.). Web.
Hanselmann R. G., & Welter, C. (2016). Origin of cancer: An information, energy, and matter disease, Frontiers in Cell and Development Biology, 4(121). doi: 10.3389/fcell.2016.00121
Nussbaum, R. L., McInnes, R. R., & Huntington, F. W. (2016). Thompson & Thompson genetics in medicine (8th ed.). Philadelphia, PA: Elsevier.
Rasnick, D. (2016). The chromosomal imbalance theory of cancer: Autocatalyzed progression of aneuploidy is carcinogenesis. Enfield, NH: Science Publishers.
Vance, G. H. (2020). Cytogenetics/cytogenomics. In E. Keohane, K. Otto, & J. Walenga, Rodak’s Hematology (6th ed.). Philadelphia, PA: Elsevier.