Cancer Biology 4th Year Biochemistry Students PDF

Cancer Biology 4th Year Biochemistry Students Zoology Department, Faculty of Science, © South Valley University  Developmental biology A single cell (zygote) generates the whole human body via division and differentiation (10^13 cells). Most of these cells are quies...

Cancer Biology 4th Year Biochemistry Students Zoology Department, Faculty of Science, © South Valley University  Developmental biology A single cell (zygote) generates the whole human body via division and differentiation (10^13 cells). Most of these cells are quiescent: G0 phase of the cell cycle, they only divide in response to a proper stimulus. 10 million cells die and are replaced in every second in our body. Cell growth and division are tightly controlled. Deregulation of these control mechanisms can lead to cancer. This depends on inherited and environmental factors.  Carcinogenesis requires several cellular changes Cancer is an ancient condition and was known to the early Egyptians. Despite this ancient lineage, two modern components, longevity and lifestyle, have major impacts on both the type and the number of cancers encountered. Carcinogenesis, the process by which cancers are generated, is a multistep mechanism resulting from the accumulation of errors in vital regulatory pathways.  It is initiated in a single cell, which then multiplies and acquires additional changes that give it a survival advantage over its neighbors. The altered cells must be amplified to generate billions of cells that constitute a cancer. As it takes time to generate these errors and cell numbers, it follows that the longer a person lives, the more likely they are to get cancer. Sadly, the dictum that cancer is a disease of old age has exceptions, in that some cancers are characterized by onset in childhood: cancers of the eye and certain leukaemias fall into this category. This explains the initial high incidence of leukaemia followed by a dip and then a rise in older people. Influence of age on cancer incidence (USA).  Etiology of cancer “Pathogenesis" Etiology is the study of the causes or origins of a disease or medical condition. It involves the investigation of the various factors that contribute to the development and progression of the disease. The term is commonly used in medical and scientific fields to describe the underlying causes of a particular condition and is often used interchangeably with the term "pathogenesis". The etiology of cancer refers to the various factors that contribute to the development and progression of the disease. Cancer is a complex and multifaceted disease, and its etiology involves a wide range of genetic, environmental, and lifestyle factors. I. Genetic factors Genetic mutations are one of the most important factors in the etiology of cancer. Mutations in specific genes can disrupt the normal cellular processes that regulate cell growth and division, leading to the uncontrolled proliferation of cells. These mutations can be inherited or acquired through exposure to various environmental factors. 1. Inherited mutations in specific genes, such as BRCA1 and BRCA2, are associated with an increased risk of developing breast and ovarian cancer. Similarly, mutations in the TP53 gene, which is involved in DNA repair and cell cycle regulation, can increase the risk of developing several types of cancer, including breast, colon, and lung cancer. 2. Acquired mutations can also contribute to cancer development. Exposure to environmental factors, such as tobacco smoke, radiation, and certain chemicals, can damage DNA and lead to mutations. In addition, errors during DNA replication or repair can also result in mutations. II. Environmental factors Environmental factors can play a significant role in the development of cancer. Exposure to certain substances, such as tobacco smoke, alcohol, and certain chemicals, can increase the risk of cancer development. For example, smoking is a major risk factor for lung cancer, while alcohol is a risk factor for liver cancer. Exposure to ionizing radiation, such as X-rays and gamma rays, can also increase the risk of cancer. This type of radiation can damage DNA and lead to mutations, which can contribute to cancer development. People who work in occupations that involve exposure to radiation, such as nuclear workers and radiologists, are at increased risk of developing cancer. Other environmental factors that may increase the risk of cancer include air pollution, water pollution, and exposure to certain viruses and bacteria. III. Lifestyle factors such as diet, physical activity, and body weight, can also influence the development of cancer. A for example, has been linked to an increased risk of In contrast, a diet high in fruits, vegetables, and whole grains may reduce the risk of several types of cancer. is also important for Regular exercise can help maintain a healthy body weight and reduce inflammation, both of which are associated with a lower risk of cancer. In addition, physical activity may help reduce the risk of several types of cancer, including breast, colon, and prostate cancer.  is also an important factor in the etiology of cancer. Obesity is associated with an increased risk of several types of cancer, including breast, colon, and kidney cancer. This may be due in part to the fact that obesity can lead to chronic inflammation and insulin resistance, both of which are associated with an increased risk of cancer. that may increase the risk of cancer include alcohol consumption, tobacco use, and exposure to sunlight. In conclusion, the etiology of cancer is complex and multifaceted, involving a wide range of genetic, environmental, and lifestyle factors. Understanding these factors is critical for developing effective strategies for cancer prevention and treatment.  Anatomy of cancer cell The structure of cancer can vary depending on the type and stage of the disease. In general, cancer cells have abnormal features that distinguish them from normal cells. These features can include changes in cell size and shape, loss of specialized cell functions, and alterations in the way cells communicate with each other. As cancer cells continue to divide and grow, they can invade nearby tissues and organs and spread to other parts of the body through the bloodstream or lymphatic system. This process is called metastasis and can lead to the formation of secondary tumors in other parts of the body.  The structure of a cancerous tumor also includes a microenvironment composed of blood vessels, immune cells, and other types of cells that support tumor growth and survival. This microenvironment can play a crucial role in the progression and response of the tumor to treatment. Overall, the structure of cancer is complex and dynamic, with changes occurring at the cellular and molecular levels as the disease progresses. Understanding the structure and behavior of cancer cells is crucial for developing effective treatments and improving outcomes for patients with cancer.  Tumor arises from normal tissue Histological analyses made it clear that tumors arise as a result of changes and proliferation of normal tissues. Histopathological analysis is still central in the diagnosis and characterization of a tumor. The identity and main morphological features of a tumor is established by the histopathologist, enabling the grouping and prognosis of the given tumor. Examples: intestinal and breast cancer  Tumor progression Normoplasia: normal tissue Hyperplasia: too much proliferation, too many cells. Metaplasia: cells normally present in a tissues are replaced/ dislocated by rapidly growing tumor cells. Dysplasia: appearance of cytological aberrations (eg. changes in the shape and size of nuclei and cells, changing staining in histological sections etc.) Neoplasia: “new tissue type”: abnormally growing cell mass.  Hyperplasia Mammary duct hyperplasia: initial and more advanced stages  Metaplasia Usually observed in the transition zone of epithelia (cervix/uterus, esophagus/gaster) If the secretory cells of the stomach appear in the esophagus, it is considered as a pre-malignant lesion.  Polyps Pre-invasive adenoma in the colon. Dysplasia  Neoplasia Breast cancer cells are already observed in the connective tissue surrounding the milk duct. Based on histopathological analyses, the following tumor progression series is likely: normal hyperplasia dysplasia neoplasia metastasis  Histopathology of cancer In the case of cancer, histopathology involves the examination of tissue samples taken from the tumor and surrounding areas. These samples are typically obtained through The pathologist examines these samples under a microscope and looks for changes in the cells and tissues that are indicative of cancer. The pathologist may also perform additional tests to identify specific molecular markers that can help with diagnosis and treatment planning.  One of the key features of cancer that can be seen on histopathology is the presence of abnormal cells. Cancer cells often have an abnormal shape and size, and may have features such as enlarged nuclei, increased mitotic activity (indicating rapid cell division), and loss of cell differentiation (meaning the cells no longer resemble normal cells of the tissue they came from). These changes can be used to classify the tumor as a specific type of cancer and determine its grade, which is a measure of how abnormal the cells appear. There are many different types of cancer, each with its own distinct histopathological features.  Carcinoma: This type of cancer arises from cells in the epithelial tissue, which is the lining of the body's internal and external surfaces. Carcinomas can occur in many different organs, including the lungs, breast, prostate, and colon. Histopathological features of carcinomas may include the presence of glandular structures, the formation of solid nests or sheets of cells, and the appearance of keratinized cells (in some cases).  Sarcoma: This type of cancer arises from cells in the mesenchymal tissue, which includes bone, muscle, and connective tissue. Sarcomas can occur in many different parts of the body, including the bones, soft tissues, and organs such as the uterus. Histopathological features of sarcomas may include the presence of spindle-shaped cells, the formation of cartilage or bone-like structures, and the appearance of large, pleomorphic cells (in some cases).  Leukemia and lymphoma: These types of cancer arise from cells in the blood or lymphatic system. Leukemias are cancers of the white blood cells, while lymphomas are cancers of the lymphatic system. Histopathological features of these types of cancer may include the presence of abnormal cells in the blood or lymph nodes, respectively. Dr. Amr M. Ali