Pathophysiology of Cancer 101: What is Cancer?
- Pink Project
- Mar 13, 2022
- 3 min read
The Pink Project
Cancer is a disorder of altered differentiation and growth. It is not a single disease as it can appear in any organ or tissue within the body. Mortality rates for cancers of all types have decreased since the 1960s but, the number of cancer deaths has increased due to the aging population. It was found that 2 in 5 Canadians (44% of men and 43% of women) are expected to develop cancer during their lifetime and about 1 out of 4 Canadians (26% of men and 22% of women) are expected to die from cancer (Canadian Cancer Society, 2021).
But what exactly is cancer? Why is it such a complex disorder? This blog will explore the pathophysiology of the disorder and how it works in the body.
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Cell Differentiation
Cell Differentiation is the process where proliferating cells become specialized. Proliferation is the creation of cells. They are assigned a function/structure/purpose based on their gene expression. All cells in your body will go through proliferation ad differentiation. This process is highly regulated through the Cell Cycle, but in some cases, errors are able to slip through the body’s checkpoint system. The process of differentiation occurs in orderly steps. Unlike controlled growth with non-cancerous cells, neoplasms, which is the new growth of abnormal cells, tend to be uncontrolled and grow at their own pace.
Neoplasms can be either benign or malignant. Benign Neoplasms are a well-differentiated (contained) tumour that resembles the tissue of origin, just with uncontrolled cell growth. They are less of a threat to health due to their slow growth and their similarity to the surrounding cells. On the other hand, Malignant Neoplasms are less well-differentiated tumours that have lost the ability to control cell differentiation & growth. They are uncontrolled and unorganized, causing damage to surrounding cells, tissues, and systems. Due to their rapid growth, they tend to create their own blood vessels to supply themselves and compress other existing vessels and organs. They may also secrete hormones, enzymes, or toxins that trigger an inflammatory response.
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Cancer Cell Characteristics
There are two main features of cancerous cells; Proliferation and the Loss of Differentiation. The Loss of Differentiation is defined through two main factors, an abnormal number of chromosomes and an abnormal nuclei.
The following key characteristics are what can help scientists determine if a cell is cancerous or not:
Genetic Instability: Cancer cells have unstable, incomplete, or unstable chromosomes and DNA
Growth Factor Dependence: Cancer cells are able to proliferate without growth factors. The growth factors are required for other cells to begin growing and running through the cell cycle.
Cell Density-Dependent Inhibition: Unlike regular cells, cancer cells are missing a command that tells them when they’ve grown large/dense enough.
Cell Cohesiveness & Adhesion: The surface cells on the tumour do not stick together well, often leading them to travel to surrounding body fluids.
Anchorage Dependence: Often, epithelial (skin) cells must be anchored to other cells or spaces in order to live and die if they detach. Cancer cells are able to live independently wherever in the body and do not require an attachment to specific areas.
Cell-to-Cell Communication: Cancer cells are unable to properly communicate with each other due to differences in their structure.
Life Span: Cancer cells differ from normal cells by having an unlimited life span. These cells can divide an infinite amount of times, but with each division the telomeres shorten, leaving more problems with each divide.
Antigen Expression: On the surface of tumours, tissue antigens mark the type of cell, expression, and DNA. Abnormal tissue antigens may mark cancerous growths.
Production of Enzymes, Hormones, and Other Substances: Cancer cells may increase, decrease, or make secretions that are abnormal to the surrounding area.
Cytoskeletal Changes: Cancer cells have abnormal cell anatomy that alters the cell cycle and cell division.
Cancer Etiology
Cancer can be caused by a multitude of factors. Genetics and heredity are major players in cancerous cell growth. On a cellular level, the microenvironment, the ecosystems that surround a tumour in the body, may also lead to mutations. Did you know that our cells can also be altered by our external environment? Environmental factors such as hormones, immunological factors, chemical carcinogens, radiation, and some viruses, like Human Papillomavirus (HPV), Epstein-Barr Virus (EBV), Hepatitis B (HBV) and Human Herpesvirus-8 (HHV-8) may also lead to cancerous growths.
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References
Canadian Cancer Society. (n.d.). Cancer statistics at a glance. https://cancer.ca/en/research/cancer-statistics/cancer-statistics-at-a-glance
Hannon, R., & Porth, C. (2017). Chapter 8: Neoplasia. In Porth pathophysiology: Concepts of altered health states (Second Canadian Edition) (2nd ed.). Wolters Kluwer.
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