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Cancer Research from Technology Networks

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The body is made up of approximately 37.2 trillion human cells - so you can truly appreciate how many that is, here is the number written out in full, 37,200,000,000,000 - that's a lot of cells.

These "normal" cells act as the body's basic building blocks and possess specific characteristics that enable them to maintain correct functioning of tissues, organs and organ systems. Normal cells:

control their growth using external signals, meaning they only grow and divide when required,

undergo programmed cell death (apoptosis) as part of normal development, to maintain tissue homeostasis, and in response to unrepairable damage,

"stick together" by maintaining selective adhesions that they progressively adjust which ensures they remain in their intended location,

differentiate into specialized cells with specific functions meaning they can adopt different physical characteristics despite having the same genome.

Cancer is a complex genetic disease that is caused by specific changes to the genes in one cell or group of cells. These changes disrupt normal cell function - specifically affecting how a cell grows and divides. In contrast to normal cells, cancer cells don't stop growing and dividing, this uncontrolled cell growth results in the formation of a tumor. Cancer cells have more genetic changes compared to normal cells, however not all changes cause cancer, they may be a result of it. The genetic changes that contribute to cancer usually affect three specific types of gene; proto-oncogenes, tumor suppressor genes and DNA repair genes.

Hallmarks of cancer

"Hallmarks of Cancer" is a term used to describe the specific characteristics that distinguish cancer cells from normal cells.
Figure 1: The 10 hallmarks of cancer, as defined by Douglas Hanahan and Robert A. Weinberg, 2011.

Normal cell vs cancer cell - the key differences

Cell shape: Normal human cells come in many shapes and sizes - as they differentiate and adopt specialized functions their shape changes accordingly - for instance, a red blood cell looks very different to a nerve cell. Different types of cells do not look alike, but, if you analyze cells of the same cell type they will look extremely similar, maintaining a uniform shape.

For years researchers have been peering down microscopes, looking for distinct features that can help them determine the difference between a cancer cell and normal cell. Cancer cells are misshapen, and appear as a chaotic collection of cells, in an array of shapes and sizes. Researchers have been investigating the relationship between cancer cell shape and a patients' outlook, and whether cell shape may also help to distinguish between the different types of cancer.

Nucleus: In normal cells, the nucleus has a smooth appearance and maintains a uniform, spheroid shape. Several structural components are involved in the regulation of nuclear morphology. One of these structural components is the nuclear lamina. Cancer cell nuclei are frequently misshapen and bulges known as "blebs" can often be observed in cells' nuclear membranes. Research suggests that this "blebbing" is caused by an imbalance in the proteins that constitute the nuclear lamina which leads to separation of the lamina fibers.

Chromatin: The fine, evenly distributed chromatin found in normal cells transforms into coarse, chromatin in cancer cells - aggregating into irregular clumps that vary in both size and shape.

Nucleolus: Tumor aggressiveness and clinical outcome can both be measured by observing the morphology of a cancer cell's nucleolus/ nucleoli. The nucleolus becomes increasingly enlarged and more irregular in cancer cells - cells can have multiple nucleoli within the nucleus.

Blood supply: Angiogenesis is defined as the development of new blood vessels that form from pre-existing vasculature. Angiogenesis is a vital process in normal cells that occurs during development, growth, and wound healing. However, it is also implicated in the growth of cancer, through the tumor's ability to secrete chemical signals that stimulate angiogenesis.

Tumors can directly and indirectly influence the blood supply they receive by either releasing pro-angiogenic signals themselves (left) or by exploiting neighboring "normal" cells, stimulating them to release pro-angiogenic signaling molecules (right).

Below we outline some of the key differences between cancer cells and normal cells.

How do cancer cells behave differently from normal ones?

As cancer cells display unique characteristics in comparison to normal cells, researchers can take advantage of these differences when coming up with ways to combat cancer.

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Cancer is a complex genetic disease that is caused by specific changes to the genes in one cell or group of cells. These changes disrupt normal cell function - specifically affecting how a cell grows and divides. This article outlines some of the key differences between cancer cells and normal cells.

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Certain popular ideas about how cancer starts and spreads-though scientifically wrong-can seem to make sense, especially when those ideas are rooted in old theories. But wrong ideas about cancer can lead to needless worry and even hinder good prevention and treatment decisions. This page provides the latest science-based information about some common cancer myths and misconceptions.

Is cancer a death sentence?

In the United States, the likelihood of dying from cancer has dropped steadily since the 1990s. Five-year survival rates for some cancers, such as breast, prostate, and thyroid cancers, now are 90 percent or better. The 5-year survival rate for all cancers combined is currently about 68 percent. For more information, see the Annual Report to the Nation on the Status of Cancer.

It is important to note, however, that these rates are based on data from large numbers of people. How long an individual cancer patient will live and whether he or she will die from the disease depend on many factors, including whether the cancer is slow or fast growing, how much the cancer has spread in the body, whether effective treatments are available, the person's overall health, and more.

Is cancer contagious?

In general, no. Cancer is not a contagious disease that easily spreads from person to person. The only situation in which cancer can spread from one person to another is in the case of organ or tissue transplantation. A person who receives an organ or tissue from a donor who had cancer in the past may be at increased risk of developing a transplant-related cancer in the future. However, that risk is extremely low-about two cases of cancer per 10,000 organ transplants. Doctors avoid the use of organs or tissue from donors who have a history of cancer.

In some people, cancers may be caused by certain viruses (some types of human papillomavirus, or HPV, for example) and bacteria (such as Helicobacter pylori). While a virus or bacterium can spread from person to person, the cancers they sometimes cause cannot spread from person to person. For more information about cancer-causing viruses and bacteria, see the NCI fact sheet on Helicobacter pylori and Cancer and our pages on HPV and Cancer and Infectious Agents.

Will cancer get worse if exposed to air?

No. Exposure to air will not make tumors grow faster or cause cancer to spread to other parts of the body. For information about how cancer spreads in the body, see our page on Metastatic Cancer.

Do power lines cause cancer?

No, not according to the best studies completed so far. Power lines emit both electric and magnetic energy. The electric energy emitted by power lines is easily shielded or weakened by walls and other objects. The magnetic energy emitted by power lines is a low-frequency form of radiation that does not damage genes. For more information, see the NCI fact sheet on Electromagnetic Fields and Cancer.

If someone in my family has cancer, am I likely to get cancer, too?

Not necessarily. Cancer is caused by harmful changes (mutations) in genes. Only about 5 to 10 percent of cancers are caused by harmful mutations that are inherited from a person's parents. In families with an inherited cancer-causing mutation, multiple family members will often develop the same type of cancer. These cancers are called "familial" or "hereditary" cancers.

The remaining 90 to 95 percent of cancers are caused by mutations that happen during a person's lifetime as a natural result of aging and exposure to environmental factors, such as tobacco smoke and radiation. These cancers are called "non-hereditary" or "spontaneous" cancers. For more information about the risk of getting cancer, see the NCI fact sheet on Genetic Testing for Inherited Cancer Susceptibility Syndromes and Cancer Causes and Risk Factors.

If no one in my family has had cancer, does that mean I'm risk-free?

No. Based on the most recent data, about 38 percent of men and women will be diagnosed with cancer at some point during their lives. Most cancers are caused by genetic changes that occur throughout a person's lifetime as a natural result of aging and exposure to environmental factors, such as tobacco smoke and radiation. Other factors, such as what kind of food you eat, how much you eat, and whether you exercise, may also influence your risk of developing cancer. For more information, see Cancer Causes and Risk Factors.

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Certain popular ideas about how cancer starts and spreads-though scientifically wrong-can seem to make sense, especially when those ideas are rooted in old theories. But wrong ideas about cancer can lead to needless worry and even hinder good prevention and treatment decisions. This page provides the latest science-based information about some common cancer myths and misconceptions.

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The study of cancer is termed oncology. Cancers have been known to mankind since ancient times. Cancer begins when cells in a part of the body start to grow out of control. Several different parts of the body may be affected by cancer.

Earliest references to cancer

Some of the earliest evidence of cancer is found among fossilized bone tumors in human mummies in ancient Egypt, and references to the same has been found in ancient manuscripts. Bony skull destruction as seen in cancer of the head and neck has been found, too.

Although the word cancer was not used, the oldest description of the disease is from Egypt and dates back to about 3000 BC. It is called the Edwin Smith Papyrus and is a copy of part of an ancient Egyptian textbook on trauma surgery. It describes 8 cases of tumors or ulcers of the breast that were treated by cauterization with a tool called the fire drill. The description adds that there is not treatment for the condition.

Origin of the word cancer

The disease was first called cancer by Greek physician Hippocrates (460-370 BC). He is considered the "Father of Medicine." Hippocrates used the terms carcinos and carcinoma to describe non-ulcer forming and ulcer-forming tumors. In Greek this means a crab. The description was names after the crab because the finger-like spreading projections from a cancer called to mind the shape of a crab.

Later Roman physician, Celsus (28-50 BC) translated the Greek term into cancer, the Latin word for crab. It was Galen (130-200 AD), another Roman physician, who used the term oncos (Greek for swelling) to describe tumors. Oncos is the root word for oncology or study of cancers.

Between 15th and 18th centuries

During the beginning of the 15th Century scientists developed greater understanding of the workings of human body and its disease processes.

Autopsies, done by Harvey (1628), led to an understanding of the circulation of blood through the heart and body.

Giovanni Morgagni of Padua in 1761 regularized autopsies to find the cause of diseases. This laid the foundation for the study of cancer as well.

It was Scottish surgeon John Hunter (1728−1793) who suggested that some cancers might be cured by surgery. It was nearly a century later that development of anesthesia prompted regular surgery for "movable" cancers that had not spread to other organs.

The 19th Century

Rudolf Virchow, often called the founder of cellular pathology, founded the basis for pathologic study of cancers under the microscope. Virchow correlated microscopic pathology to illness.

He also developed study of tissues that were taken out after surgery. The pathologist could also tell the surgeon whether the operation had completely removed the cancer.

History of the causes of cancer

There have been numerous theories of causes of cancer throughout ages. For example, the ancient Egyptians blamed Gods for cancers.

Hippocrates believed that the body had 4 humors (body fluids): blood, phlegm, yellow bile, and black bile. He suggested that an imbalance of these humors with an excess of black bile in various body sites could cause cancer. This was the humoral theory.

After the humoral theory came the lymph theory. Stahl and Hoffman theorized that cancer was composed of fermenting and degenerating lymph, varying in density, acidity, and alkalinity. John Hunter, the Scottish surgeon from the 1700s, agreed that tumors grow from lymph constantly released from blood.

Zacutus Lusitani (1575−1642) and Nicholas Tulp (1593−1674), doctors in Holland, concluded that cancer was contagious. Throughout the 17th and 18th centuries, some believed that cancer was contagious.

It was it 1838 that German pathologist Johannes Muller showed that cancer is made up of cells rather than lymph. Muller proposed that cancer cells developed from budding elements (blastema) between normal tissues.

Rudolph Virchow (1821−1902), suggested that all cells, including cancer cells, are derived from other cells. He proposed the chronic irritation theory. He believed that cancer spread like a liquid. In the 1860s, German surgeon, Karl Thiersch, showed that cancers metastasize through the spread of malignant cells and not through a liquid.

Until 1920's trauma was thought to be the cause of cancers.

History of cancer screening and detection

Screening for cancer helps in early detection. The first screening test to be widely used for cancer was the Pap test. It was developed by George Papanicolaou as a research method in understanding the menstrual cycle. He then noted that the test could help in finding cervical cancer early and presented his findings in 1923.

It was then that the American Cancer Society (ACS) promoted the test during the early 1960's and it became widely used as a screening tool.

Modern mammography methods were developed late in the 1960's and first officially recommended for breast cancer screening by the ACS in 1976.

Development of cancer surgery

It was quite early in the history of knowledge of cancers that surgery was considered a modality of treatment of cancers. Roman physician Celsus had noted that despite surgery the cancer seems to come back. Galen wrote about techniques of surgery for cancers. Surgery then was very primitive with many complications, including blood loss. Surgery for cancers flourished in the 19th and early 20th centuries after advancement of anesthesia.

Bilroth in Germany, Handley in London, and Halsted in Baltimore are the pioneers of cancer surgery. William Stewart Halsted, professor of surgery at Johns Hopkins University, developed the radical mastectomy during the last decade of the 19th century for breast cancers. His work was based on W. Sampson Handley.

Stephen Paget, an English surgeon during this time found that cancers did spread via blood circulation. This understanding of metastasis became a key element in recognizing patients who might and might not benefit from cancer surgery.

Development of radiation therapy

In 1896 a German physics professor, Wilhelm Conrad Roentgen, discovered and presented the properties of X rays. It was within the next few months that X rays were used for diagnosis and in the next 3 years it was used in treatment of cancers. Radiation therapy began with radium and with relatively low-voltage diagnostic machines.

Development of chemotherapy

It was seen that during the World War II, soldiers exposed to mustard gas during military action developed toxic bone marrow suppression. Soon a similar chemical nitrogen mustard was found to work against a cancer of the lymph nodes called lymphoma. This laid foundation for several new drugs that could be used against cancers.

Development of hormone therapy

In the 19th Century, Thomas Beatson discovered that the breasts of rabbits stopped producing milk after he removed the ovaries. He tried removal of the ovaries (called oophorectomy) in advanced breast cancer. This was discovered before the hormone itself was discovered. His work provided a foundation for the modern use of hormone therapy, such as tamoxifen and the aromatase inhibitors, to treat or prevent breast cancer.

Development of immunotherapy

With the understanding of the biology of cancer cells, several biological agents have been developed in treatment of cancers. These are called biological response modifier (BRM) therapy. Notable among these are the monoclonal antibodies.

The first therapeutic monoclonal antibodies, rituximab (Rituxan) and trastuzumab (Herceptin) were approved during the late 1990's to treat lymphoma and breast cancer, respectively. Scientists are also studying vaccines that boost the body's immune response to cancer cells.
The later part of the 20th century also saw the development of targeted therapies like growth factor inhibitors like trastuzumab (Herceptin), gefitinib (Iressa), imatinib (Gleevec), and cetuximab (Erbitux). Another targeted approach is anti- ngiogenesis or anti-blood vessel formation drugs like bevacizumab (Avastin).

Further Reading

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The study of cancer is termed oncology. Cancers have been known to mankind since ancient times. Cancer begins when cells in a part of the body start to grow out of control. Several different parts of the body may be affected by cancer.

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1. by chemical carcinogens e.g. in tobacco smoke
2. by ionising radiation e.g. UV and X-rays

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Cancer is uncontrolled cell division.