Biological Sciences
Tumour
A tumor is an abnormal mass of tissue that results from the uncontrolled division of cells. Tumors can be benign or malignant, with the latter having the potential to spread to other parts of the body. They can occur in various organs and tissues and are often associated with cancer. Tumors can be diagnosed through imaging techniques and biopsies.
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8 Key excerpts on "Tumour"
eBook - PDF- David J. Argyle, Malcolm J. Brearley, Michelle M. Turek, David J. Argyle, Malcolm J. Brearley, Michelle M. Turek(Authors)
- 2009(Publication Date)
- Wiley-Blackwell(Publisher)
1 INTRODUCTION: CANCER BIOLOGY AND TERMINOLOGY David J. Argyle A Definition of Tumor • A tumor is any tissue mass or swelling and may or may not be neoplastic. • Neoplasia is the abnormal growth of a tissue into a mass. It is usually phenotypically recognized by the fact that its cells show abnormal growth patterns and are no longer under the control of normal homeostatic growth-controlling mechanisms. • Neoplasms can be considered as either benign or malignant tumors. Although the range of mechanisms involved in the development of tumors and the spectrum of tissues from which tumors are derived is diverse, they can be classified into three broad types: 1. Benign Tumors : Broadly speaking, these tumors arise in any of the tissues of the body and grow locally. They can grow to a large size but are not invasive. Their clinical significance is their ability to cause local pressure, cause obstruction, or form a space-occupying lesion such as a benign brain tumor. Benign tumors do not metastasize. 2. In situ Tumors : These are often small tumors that arise in the epithelium. Histologically, the lesion appears to contain cancer cells, but the tumor remains in the epithelial layer and does not invade the basement membrane or the supporting mesenchyme. A typical example of this is preinvasive squamous cell carci-noma affecting the nasal planum of cats. 3. Cancer : This refers to a malignant tumor, which has the capacity for both local invasion and distant spread by the process of metastasis. A Definition of Cancer • Cancer is a disease of all vertebrate species and is well documented throughout history, with fossil records indicating dinosaurs of the Jurassic period suffered from the disease. • The Greek physician Galen is accredited with describing human tumors of having the shape of a crab, with leglike tendrils invading deep into surrounding tissues—hence, the term cancer.
eBook - PDF- John Roboz(Author)
- 2002(Publication Date)
- CRC Press(Publisher)
81 Relevant Concepts of Cancer Medicine and Biology 3.1 CLASSIFICATION AND EPIDEMIOLOGY The words tumor (Latin, tumere = to swell) and neoplasm (neo = new, plasma = formation) are used synonymously to describe abnormal tissues characterized by unregulated cellular growth to form a mass without a defined structure. The pathologic process that results in the formation and growth of neoplasms is called neoplasia. Cancer (Latin, for crab) is a general term used to describe any of various types of malignant neoplasms causing over 200 diseases of multicellular organisms. Cancers share several characteristics, including that they originate from mutant, genetically dys- functional cells; they escape normal growth controls; and they invade and colonize normal tissues. On its way to becoming a full-fledged malignant tumor, a nascent neoplastic clone must prevail through a remarkable series of events and must undertake a number of exceptional maneuvers. These include bypassing programmed cell death, circumventing growth restraining signals, growing without growth factors from other cells, evading immunological surveillance, appropriating a vascular supply, burrowing into surrounding tissues, traversing blood or lymph vessels to travel to distant sites, recognizing an appropriate environment for crossing out of the vessels, and finally establishing secondary tumors. Only about 0.1% of the breakaway cells survive after entering the circulation, and most of those are captured in the first capillary bed encountered. In the specific case of cells in the lymph system, those cells arrested in the subcapsular sinuses of the lymph nodes may begin to grow. Other lymph borne-malignant cells may enter the blood vascular system via the lymphatic interconnections in the venous system. 3.1.1 S OLID T UMORS All solid neoplasms have a parenchyma that comprises the neoplastic proliferating cells and a stroma that consists of the supporting connective tissue and blood supply required for growth.
eBook - PDF- Ihtesham ur Rehman, Zanyar Movasaghi, Shazza Rehman(Authors)
- 2012(Publication Date)
- CRC Press(Publisher)
33 3 The Biology of Cancer To understand chemical structural properties of cancer and associated changes with the progression of disease, it is important to understand the biology and chemistry of cancer. The term neoplasia , which literally means new growth , is used clinically to describe pathologic tissue masses, which grow independent of and faster than normal tissues. Most of the body cells repair and reproduce themselves similarly in spite of their dif-ferent functioning and appearance. As long as this process takes place in an orderly manner, everything is under control. However, when it gets out of control, a lump, called a Tumour , develops. A neoplasm (Tumour) may be classified as in situ, benign, or malignant, based on its potential to harm the host body. Malignant Tumours are also called cancers [1,2,3]. Benign Tumours are not considered cancer. They do not threaten life because they do not spread to other organs, and once they are removed, they rarely reappear. In situ Tumours look like cancer in their morphology. In gen-eral, they develop in epithelium. These small Tumours remain in the epi-thelial layer. A malignant Tumour consists of cancer cells that sometimes spread away from the original (primary) cancer to other organs through the lymphatic system and bloodstream causing damage to organs and tis-sues near the Tumour. When they get to another part of the body, they may divide forming a new Tumour called a secondary or a metastasis Tumour [4]. A biopsy is used by doctors to decide whether a Tumour is benign or can-cerous in which a small sample of cells is examined under a microscope. Uncontrolled growth is the core property of cancers, which were known to the early Egyptians [3,5]. Hippocrates reportedly distinguished benign from malignant tissues [6].
eBook - PDFColor Atlas of Pathology
Pathologic Principles, Associated Diseases, Sequela
- Urs-Nikolaus Riede, Martin Werner, Ursus-Nikolaus Riede(Authors)
- 2004(Publication Date)
- Thieme(Publisher)
For this to occur, the new tissue substrate must be com-patible with the tumor cells. Referred to as metasta-sis, this process of tumor seeding usually occurs through the blood or lymph vessels. From a clinical standpoint, it is the most serious tumor complica-tion and marks an ominous turning point in the course of the tumor disorder. Tumor complications also include the paraneoplastic syndromes, which are usually attributable to the fact that the protein machinery of the tumor cells synthesizes “non-sense” proteins or proteins that act as antigens. Tumor classification : Deranged proliferation and differentiation characterize the growth and appearance of a tumor. Therefore, a tumor’s mor-phology provides information about its origin and its biologic behavior. Histologic evaluation of a tu-mor provides the basis for the therapy concept used in treating it. General Definition of “Tumor” Synonym: neoplasia. A tumor is an abnormal mass of tissue resulting from autonomous, progressive, excessive prolif-eration of body cells not integrated into normal tissue. Exception: Postpartum choriocarcinoma is a malignant tumor of placental trophoblasts which are the child’s own cells. Note: “Tumor” in the original wider sense denotes any circumscribed increase in volume of a tissue (a swelling). Several types of tumors are differentiated according to their biologic behavior or malignancy status. Benign Tumors These are limited circumscribed tumors that do not metastasize into other regions of the body, do not recur after resection, and do not have a fatal outcome. Note: Two exceptions: A tumor occurring in an unfavorable anatomic location that causes compres-sive destruction of vital structures. For example, be-nign pituitary tumors cause compressive atrophy of glandular tissue. A tumor with excessive hormone pro-duction that can cause fatal metabolic derange-ments. For example, an islet cell adenoma of the pan-creas causes hyperinsulinism.
- Narayan S Hosmane, John A Maguire, Yinghuai Zhu(Authors)
- 2012(Publication Date)
- World Scientific(Publisher)
For instance, cigarette smoking increases the risk of 7 2 abnormal cell growth in the lungs. Cancerous tissue can form in any region of the body. In most cases, a solid tumor (mass of cells) is formed. The out-of-control growth of cancerous cells poses many threats. Due to their rapid growth and immortality, the cells can quickly spread (metastasize) to other locations in the body, causing further differentiation and damage. 8 Boron and Gadolinium Neutron Capture Therapy for Cancer Treatment Figure 2.1 Origin of cell mutation. Not all cancers exist as a solid tumor; there are other forms that can be referred to as “liquid tumors.” 12 A common type of liquid tumor is leukemia (a cancer of the blood, which is usually characterized by an increase in white blood cells). Cancers of the blood and blood-forming organs, such as bone marrow, are classified under “liquid tumors.” 2.2. Characteristics of Tumors A tumor can be classified as “benign” or “malignant” (see Scheme 2.1). 13 A simple way to remember which type of tumor is more severe is to think that benign sounds like “be nice.” A malignant tumor is the type of tumor that is capable of spreading to different areas of the body, whereas a benign tumor will not spread to other regions. Benign tumors are non-metastatic (unable to spread to different areas) because they are contained within a fibrous capsule that prevents them from invading surrounding tissue. Benign cells are differentiated, meaning that they closely resemble the normal tissue from which they are derived. Undifferentiated or “anaplastic” cells vary in size and shape and are usually piled on top of one another in an unorganized manner and are not contained within a cap-sule. Anaplastic cells are of the type that can penetrate blood vessels and lymphatic tissue, spreading to different regions of the body.
eBook - ePubCancer
Basic Science and Clinical Aspects
- Craig A. Almeida, Sheila A. Barry(Authors)
- 2011(Publication Date)
- Wiley-Blackwell(Publisher)
in situ, or contained solely within the tissue in which it originated; the abnormal cells have not spread to surrounding tissues or other areas of the body. In fact, there is typically a well-defined border between a benign neoplastic growth and normal tissue. Benign neoplastic growths are usually slow growing and although they are generally not life-threatening, they can become dangerous based on their location and whether or not their growth disrupts or interferes with normal healthy tissue functions. Their self-contained nature is an added benefit that often allows the entire tumor to be surgically removed, unless it is in an inoperable position, such as within an organ rather than on the surface or adjacent to major blood vessels or the spinal cord.A concern with benign growths is that they can progress into the far more serious malignant or cancerous neoplasms. Principal among the distinguishing features of malignant tumors is that they are not contained solely within the tissue in which they originally developed. This means that a portion of the tumor has grown into one or more of the surrounding tissues or has spread to a distant location in the body. Metastasis, the process by which malignant cells travel from the original (primary) tumor to other (secondary) sites in the body, is often accomplished through the use of either the circulatory or lymphatic systems (Figure 5.6 ).Normal tissues consist of differentiated cells performing specific functions. Malignant tissue typically exhibits anaplasia, the presence of undifferentiated cells that bear no resemblance to the cells normally found in that location. The presence of undifferentiated cells is a reflection of what is normally present during embryonic and fetal development when tissues are going through their formative stages. Since undifferentiated cells are involved in tissue formation they divide frequently. As a result, malignant tissues often exhibit a high mitotic index,
eBook - PDF- Caterina A. M. La Porta, Stefano Zapperi(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
2 The Biology of Cancer Cancer results from abnormal cellular growth. It is considered to be benign when localised in situ while it is defined to be malign and metastatic when it is invasive and spreads inside the body through blood or lymphatic vessels. Cancer progres- sion can be interpreted as an evolutionary process, as we discuss in Section 2.1. In spite of the increasing knowledge gained on the molecular mechanisms involved in the deregulation of cancer cells, such as the identification of many oncogenes and oncosuppressors (discussed in Section 2.2), many open questions still exist about the origin of cancer cells. In Section 2.3, we introduce a key oncosuppressor gene which is of fundamental importance for cancer development: P53, also known as the “guardian of the genome.” While important oncogenes and oncosuppressors clearly exist, cancer involves a multitude of different genes requiring an integrative data-based approach (Section 2.4). Another important issue that is still under investigation is the presence of a sub- population of more aggressive cancer cells, usually described as cancer stem cells (Section 2.5) (CSCs). The molecular aspects related to the capability of cancer cells to receive nutrients from the environment through existing vessels, and the ability of the same cancer cells to induce vessel formation (angiogenesis), are two critical aspects of the biology of cancer that we illustrate in Section 2.6. Further- more, in Section 2.7, we illustrate the spread of cancer cells inside the body in the metastatic process. All together these aspects will be discussed here, combining biological and physical viewpoints. In this perspective, the cancer ecosystem is the combination of physical forces and biochemical ingredients. Finally, the new diag- nostic tools for the identification of a cancer cell are also discussed and critically reviewed (Section 2.8).
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Orange Apple(Publisher)
Cancer cell biology Tissue can be organized in a continuous spectrum from normal to cancer. Often, the multiple genetic changes which result in cancer may take many years to accumulate. During this time, the biological behavior of the pre-malignant cells slowly change from the properties of normal cells to cancer-like properties. Pre-malignant tissue can have a distinctive appearance under the microscope. Among the distinguishing traits are an increased number of dividing cells, variation in nuclear size and shape, variation in cell size and shape, loss of specialized cell features, and loss of normal tissue organization. Dysplasia is an abnormal type of excessive cell proliferation characterized by loss of normal tissue arrangement and cell structure in pre-malignant cells. These early neoplastic changes must be distinguished from hyperplasia, a reversible increase in cell division caused by an external stimulus, such as a hormonal imbalance or chronic irritation. ________________________ WORLD TECHNOLOGIES ________________________ The most severe cases of dysplasia are referred to as carcinoma in situ. In Latin, the term in situ means in place, so carcinoma in situ refers to an uncontrolled growth of cells that remains in the original location and has not shown invasion into other tissues. Nevertheless, carcinoma in situ may develop into an invasive malignancy and is usually removed surgically, if possible. Clonal evolution Just like a population of animals undergoes evolution, an unchecked population of cells also can undergo evolution. This undesirable process is called somatic evolution, and is how cancer arises and becomes more malignant. Most changes in cellular metabolism that allow cells to grow in a disorderly fashion lead to cell death.
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