Cancer Doubts .com
  Information for patients researching their options

Learn about cancer and
Talk to your doctor with confidence

  Cancer information  

01 What is cancer?
02 Cancer symptoms and screening (how cancer is detected)
03 Causes of cancer
04 Can cancer be prevented?
05 Cancer Stages
(how long do patients live?)
06 Cancer treatment and therapy (how cancer is treated)
07 Types of doctors who treat cancer
08 Choosing a doctor (or getting a second opinion)
09 Preparing for Chemotherapy and Radiotherapy
10 Cancer support (patient psychology and feelings)
11 Cancer suport - How friends can help
12 Is it important to do my own research? (or do I just follow doctor's orders)
13 Cancer information (research your treatment options)
14 Alternative and complementary treatments for cancer
15 Avoiding dubious treatments
16 How medical research is done (how to read medical research papers)
A About this site

What causes cancer?

Cancer happens when healthy cells in the body malfunction, and start to multiply without stopping. So whatever causes these cells to malfunction is the cause of cancer. The physical form that cells take and the way they work is determined by their DNA, and any damage to the DNA can cause the cell to behave in abnormal ways. DNA can be damaged in two ways:

1. if radiation or some other carcinogen causes the DNA molecule to be mutated (anything that causes cancer is called a carcinogen)

2. if the DNA is somehow damaged when cells undergo their normal multiplication process. When cells multiple, they literally divide into two and a copy of the original DNA molecule is made for the duplicate cell. Sometimes, there are errors in the copying process and the second cell gets a mutated version of the original DNA. This can be caused by radiation or carcinogenic chemicals. It can also be by pure chance. There are millions of cell divisions that happen over our lifetime, and it is almost impossible for every single division to be error free. There are checks in the duplication process to eliminate cells that are defective, but some errors do get through. Things, like viruses, repeated injury, inflammation, or hormonal imbalances that cause cells to constantly multiply will also increase the chances of an error occurring at some point.

DNA damaged by carcinogen

Image: A computer generated image showing how a DNA molecule is damaged by the carcinogenic aromatic molecule amine 2-aminofluorene (AF). The white and red helix structure is the DNA molecule. The AF molecule is color coded in blue. The damaged section of the DNA molecule is in yellow color. In this case, the damaged section is the guanine nucleobase. Its partner is the cytosine nuclebase colored in gray. (DNA is made up of many base pairs, made up of the component nucleobases cytosine, guanine, adenine, thymine, also known by their abbreviations C, G, A, T) Source: Wikimedia Commons, public domain image.

The behavior of cells is also determined by the various molecules in the body that it comes into contact with. Each cell has receptors on its surface, much like a piece of jigsaw puzzle. Ligand molecules such as hormones, neurotransmitters, cytokines and growth factors, can attach to these receptors and trigger the cell to do certain things like reproduce, or die. (Ligand simply means any substance that can bind to a biomolecule. These molecules are called ligands because they connect to the receptors on the cell's surface) This receptor and trigger mechanism is also known as a cellular signalling pathway, because it is a path by which a signal can be sent into a cell to affect its behavior. The human body is a finely balanced system of interactions between cells and these molecules, so that all cells co-operate and the body can function properly. However, if the cells come into contact with unexpected molecules, or fail to come into contact with "regular" molecules, then the normal metabolic processes of the cell can also be disrupted. For example, when liver cells somehow leave the cluster of cells that make up the liver organ, molecules in other parts of the body will come into contact with it and tell it to shut down. If it doesn't encounter these cells, then it won't shut down, and can become dangerous because it is performing liver functions in a part of the body where it shouldn't be doing so. Likewise, a damaged cell will normally come into contact with a molecule that will trigger it to shutdown, but if the required molecule isn't available, then the damaged cell may continue living and multiplying. There are probably thousands of such molecules that affect the way our bodies work, and not all of them are known to science. Scientists are still discovering new cell signalling pathways. There are many things that could cause these molecules to be absent, such as the presence of carcinogenic chemicals in the body.

TGF-B cell signalling pathwayTGFb Cell Signalling pathwayTGFb Cell Signalling Pathway
TGFb Cell Signalling PathwayTGFb Cell Signalling Pathway

Image: An illustration of the TGF-beta cell signalling pathway. The cytoplasm is a fluid that is inside a cell. The nucles refers to the nucles of the cell. As you can see, the signalling pathway is a complex series of interactions of molecules inside and outside the cell. Source: Wikimedia Commons, used under the GNU license. Image Author: Jerome Walker

How do carcinogens get into our bodies, and what are known carcinogens? We can be exposed to radiation simply by being near a radioactive source. This can happen if we undergo too many X-rays, are near a nuclear accident, or happen to live near radioactive rocks in the ground. Many carcinogenic chemicals may also be in our environment, such as coal tar or cigarette smoke, or even in our food. For example, it is believed that the charred bits of barbequed meat are carcinogenic.

Scientists also study the behavior of human populations to try to identify behaviors or habits that may cause cancer. This is known as epidemiology, and it involves documenting the behavior and diet of a large group of people, and observing how their health progresses over the years. If it is observed that a high proportion of people with a certain behavior or diet get cancer, then scientists can zoom in an analyze the particular item that may be responsible. For example, epidemiologists have observed that many people who eat lots of meat and fats get colorectal cancer, whereas many people who eat lots of fruits and vegetables do not get colorectal cancer. This leads to the theory that high meat and fat diets cause colorectal cancer, though the exact series of chemical and molecular interactions that cause this is still not known. As you might expect, such conclusions are not always accurate. For example, what happens if the high vegetable diet people were predominantly of Asian origin, whereas the high meat diet people were of European origin? Might not the genetic differences be the real reasons for the difference in colorectal cancer rates?

Immune System
There is also a belief among some scientists that a weakened immune system can allow cancers to appear. In a healthy human body, the immune system's killer T-cells and NK cells (both are a type of immune cell known as lymphocytes) are able to recognize most damaged cells because their surface receptors are different from normal cells. (Often, the damaged DNA that causes them to behave wrongly also causes them to look different on the surface) They attach themselves to damaged cells and inject toxins into them, causing the damaged cells to break apart and die. It is believed that a weakened immune system, for example caused by stress, can reduce the numbers of T-cells and NK cells circulating, thus allowing cancerous cells to replicate until there are too many of them for the immune system to overcome.



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Medical information for cancer I am not a medical professional; please consult your doctor for a medical opinion. This is my attempt to explain cancer to anyone who is affected by it. If this site helps just one person, then it will have served its purpose.


 Cancer Links
Prominent research and treatment centers
Stanford Cancer Center
Memorial Sloan Kettering
M.D. Anderson Cancer Center
Kimmel Center at Johns Hopkins
Mayo Clinic
Information on Drugs
Drugs at FDA
NCI Drug Info
Complementary and Alternative Medicine Information
Sloan Kettering
(Integrative Medicine Service)
Medline Plus
American Cancer Society
PDR (Herbals and Supplements)
Complementary Medicine and Supplement Suppliers
Cuesta Agaricus Mushrooms
Agaricus Farm Mushrooms
Mitobi Mushrooms
Freshes Mushrooms [Bulk]
AllStarHealth [Maitake D-Fraction]
Maitake Products [D-Fraction]
LifeStream [BRM 360 capsules]
Himalaya Herbals [Ashwagandha]
Vita Green [Yun Zhi extract]
Clinical Trials
Clinical Trials (NIH)
Research Papers
National Center for Biotechnology Information
Google Scholar
New Drug Approvals / Drugs in the pipeline
FDA approvals
Helpful Books and Sites
Chemotherapy and radiation therapy survival guide
The biology of cancer
Patient Stories
Andrew Grove
Steve Dunn



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Site Copyright © 2008 Wei-lung Wang. Top banner images from the Wikimedia Commons, and used under the terms of the GNU General Public License.