Our body is composed of billions of cells. Normally the growth and reproduction of every cell is regulated by a complex series of signaling pathways. This regulation determines how the tissues and organs in the body function, as well as determining their size.
Each individual cancer is a clone that arises from a single cell.
During a person's lifetime changes may occur in the genetic material of the cells. Most of the reasons for these changes are still unknown. These changes interrupt the cell regulation process resulting in uncontrolled cell proliferation. The result is a mass or growth, also called a tumor.
The cells within malignant tumors have the ability to invade neighboring tissues and organs, thus causing the disease to spread. It is also possible for cancerous cells to break free from the tumor site and enter the bloodstream, causing the disease to spread to other organs. This process of the spreading of cancer cells is called metastasis.
A biopsy is a sampling of a small group of cells or tissue taken by the physician from the suspicious tumor. It is generally examined under a microscope by a pathologist.
A biopsy may be performed in several different ways and the decision as to which one is the most effective depends on the tumor type, its location and the general health of the patient.
A biopsy is an important step in distinguishing malignant from benign tumors and it might also provide the physician with other information for a diagnosis.
The pathology report after surgery contains a description of the gross and the microscopic examination of the surgical specimen. First, a macroscopic or gross description, as it looks to the naked eye, is provided. This includes the tumor location, size, weight, color and any other distinguishing characteristics.
Tissue specimens are then embedded in paraffin blocks, cut into slices and processed. Once prepared, they become the basis for pathology slides so that they can be carefully examined under a microscope.
The microscope examination gives details of how the tumor cells look compared with normal cells (e.g. the size and shape of the cells, the nucleus, frequency of dividing cells that are seen, etc.). The whole procedure (preparation and examination) might take two weeks or even more.
The pathology report plays an important role in cancer diagnosis and staging. Since it describes the extent of the tumor and its unique characteristics, it can help a great deal in determining treatment options.
The ultimate goal of cancer treatment is to stop the primary tumor cells from growing and spreading, thereby destroying as many of these cells as possible.
There are different types of cancer treatment. The most common cancer treatment options are surgery (the first treatment option if the tumor can be taken out of the body), radiation therapy and anti-cancer drugs (e.g. chemotherapy, hormonal therapy).
Cancer treatment may consist of a single therapy or a combination of therapies. Treatment decisions are based upon the cancer type and stage, the tumor characteristics, and the patient's general health and preferences.
Anti-cancer drugs have different mechanisms of action. However, most of these mechanisms are based on inhibiting certain important steps in cell growth and division, thus tending to work best in rapidly dividing cells. Since cancer cells are dividing rapidly, they are the most susceptible to damage from this therapy. There are also drugs that help the body's immune system to destroy cancer cells more effectively.
Similarly, radiotherapy interferes in the cell division process by damaging the genetic material of these cells, preventing them from reproducing and causing them to die.
Local therapy is directed towards the tumor site (e.g. surgery which is performed to remove the tumor and/or radiation therapy).
Local therapy aims to remove and/or destroy cancer cells in the particular tumor site and surrounding area.
Systemic therapy travels through the bloodstream reaching cancer cells all over the body (e.g. chemotherapy which is commonly administered through a vein or given orally).
Systemic therapy is designed to inhibit the growth, division and spread of cancer cells throughout the body (e.g. different anti-cancer drugs).
Most side effects of chemotherapy and radiotherapy are caused by the effect of cell destruction of these treatments. Both chemotherapy and radiotherapy target cells which divide and multiply rapidly, thereby they are most effective in killing cancer cells (whose mechanism of division and multiplying is uncontrolled). Some cell types (e.g. skin cells, bone marrow cells), even in a normal state, divide and multiply more rapidly than others (e.g. muscle cells, nerve cells). For this reason, these cells are much more affected by the chemotherapy and/or radiotherapy, which lead to the treatment side effects. However, normal cells have the ability to renew themselves much better than cancer cells, by special mechanisms. As a result, they usually recover quite well between the treatment cycles and after treatment, as opposed to the cancer cells which lack these mechanisms of repair and therefore are subsequently destroyed.
Side effects may vary between different types of anti-cancer drugs given, and even after the same drug different people might react differently.
Tumor markers are substances that are produced by tumor cells (or by the body in response to tumor cells) and secreted also to the blood where they can be measured with a simple blood test. There are different tumor markers. Most of them are not associated with a specific type of cancer but with two or more cancer types. Some tumor markers are always elevated in specific cancers, but not everyone with a specific type of cancer will have a higher level of a tumor marker associated with that cancer. No tumor marker is specific for cancer. In other words, there is no "universal" tumor marker that can detect any type of cancer and most are also found in low levels in healthy people, or can also be associated with non-cancerous diseases, thus being less predictable.
For these reasons tests for tumor markers are usually combined with other parameters. They are used for help in detecting, diagnosing and managing some types of cancer as follows:-
In those cases that the pathology results are inconclusive, elevated tumor markers that are associated with a specific type of cancer may help in identifying the exact type of cancer. In other cases the level of the tumor markers at the time of diagnosis may reflect the extent of disease, thus being helpful throughout the process of treatment decision- making.
Tumor marker levels are also measured periodically during cancer therapy in conjunction with other clinical parameters, such as radiological findings and patient complaints, to monitor a treatment success: a decrease in the level of a tumor marker may indicate that the cancer is responding to treatment, whereas an increase may indicate that the cancer is not responding and the specific drug given should be changed. Conclusions based on tumor markers are seldom based on one test result but on a series of test results called serial measurements. A series of increasing or decreasing values is more significant than a single value. It is important to note that timing of the tests is also significant and tests done too soon may be falsely elevated.
As mentioned previously (see above: "Cancer characteristics"), during a person's lifetime changes may occur in the genetic material of the cells. Some of these changes interrupt the cell regulation process, causing an uncontrolled cell proliferation. The result is a mass - or growth, also called a tumor.
Each patient has unique variations of his tumor genome, which are considered to be the "fingerprints" characterizing his malignancy. Some of these variations / mutations might influence the tumor behavior and its response to the treatment given; thus, two patients diagnosed with the same type of malignancy (e.g. lung cancer), may respond differently to the same anti-cancer drug, due to the differences between their genomic characteristics.
Personalized medicine is the use of genomic information of each patient in order to "customize" unique health management. Identification of tumor genetic markers that play a role in the tumor cells' behavior and response to a specific treatment given, may allow doctors to "tailor" the most suitable treatment not only for a specific cancer, but for a patient's specific cancer.
The past decade has seen incredible progress in the development of drugs which interfere with cancer cells' behavior by targeting specific "fingerprints" of cancer. This new approach to cancer treatment – marked and specific, targeted and customized, may offer patients invaluable, additional options and improve both the course of their disease and its prognosis.