Recently our family has been once again forced to deal with a diagnosis of cancer. I have avoided writing on this subject in the past but have decided to write a brief article on the advances in cancer treatments. I enlisted the help of my good friend and research molecular biologist, Vera Chang from Oregon State University.
Anyone who has been diagnosed with cancer, or has a family member afflicted with this disease, knows all too well how difficult it can be to treat. Beyond the disease itself, there is the stigma and gloom that accompanies it. Despite the promises of new treatments, it is still a horrifying and gut wrenching illness.
Diagnosed early, cancer is often curable, and the survivability of many forms of cancer has risen steadily as new research and new treatments have been discovered. If the diagnosis is not made early, prospects for a full recovery are remote.
Most of the various forms of cancer are not caused by pathogens for which we can develop a vaccine. It is a particular degeneration of our cells that multiply and changes into entirely new cell-forms that become a tumor. The tumor then sends out cells and spreads in processes known as invasion and metastasis.
Traditional methods of treating cancer are surgical removal of the tumor and adjacent tissues followed by chemotherapy and radiotherapy. The problem with these treatments is their lack of specificity. Chemotherapies and radiotherapies target both cancer cells and healthy cells. Today, researchers are developing new ways to battle this disease by targeting the mechanisms that allow cancer cells to form, grow and spread.
All cells in our bodies require oxygen and nutrients (and the removal of waste products) to survive. Cancer cells are no different. As a cluster of cancer cells grows larger, those cells at the center get further away from the blood vessels that bring the necessary oxygen and nutrients to the body’s cells.
Cancer cells are still OUR cells, and like all cells, they cannot survive without oxygen and nutrient. When the cancer cells begin to grow rapidly, they become starved for oxygen and nutrients. These cells release chemicals called angiogenic factors (FGF-1 and VEGF) that stimulate proliferation of nearby endothelial cells to form new blood vessels to bring oxygen and nutrients to the cancer cells. Without angiogenesis, the cancer cells cannot grow or spread.
Once new blood vessels form, cancer cells have access to other tissues and organ systems; as the tumor grows, it takes up all the resources that the blood vessels provide causing pressure on surrounding tissues. Because cancer cells grow much faster than normal tissue, they can spread through the lymphatic system, part of our immune system, invade nearby tissues, and travel through the blood stream.
Cancer researchers have identified three ways tumors can invade surrounding tissue. First, tumors can grow too large and force themselves mechanically into nearby soft tissue. Second, tumors can break down cell tissues using enzymes. These same enzymes are found in normal cells and are used to break down invading bacteria or viruses or to repair damage to the cell structure. They are a critical part of the healing process. Unfortunately, some cancer cells contain significant amounts of these enzymes, far more than normal cells. The third way tumors invade by is by producing cells that move around far more efficiently than normal cells. Researchers have discovered a substance produced by cancer cells that enable them to move, although they are not yet certain how this material plays a part in the spreading of cancer.
As resources become scarce at the origin of tumor growth, some cancer cells travel a long distance in the body. This process is called metastasis. Some cancer cells change their shape or digest the wall of the blood vessels or lymphatic vessels to get into the blood stream. Once in the blood stream, these cells can travel to other organ systems (for example, breast cancer cells metastasize to the lungs for the unlimited supply of oxygen, while colon cancer cells metastasize to the liver for an endless source of nutrition).
Scientists are developing custom-made treatments, called targeted therapies, to block the growth and spread of cancer directly without harming healthy cells. One of the targeted therapies uses our immune system as the weapon.
Our immune system is a complex arrangement of different cell types and more than 100 different chemicals whose mission is to protect us from foreign organisms like bacteria and viruses. These cells are imbued with the ability to recognize any substance as either belonging to the body or foreign (invader). Once the immune system recognizes a material as an invader, various cells and hundreds of different chemicals come together to coordinate an attack and remove the invader. Our immune system has evolved over millions of years to protect us from the continual onslaught by invading organisms. However, cancer cells are not invaders. They are an enemy from within that has developed ways to mask themselves from our immune system.
The primary purpose of targeted drugs is to help our immune system recognized these cancer cells by targeting unusual substances found in cancer cells like the proteins cancer cells require for growing and moving. Once cancerous proteins are found, our immune system will start attacking either the proteins themselves or the cell producing them. Targeting these proteins, and aiding the immune system to attack cancer is exciting research because these drugs can prevent or reduce cancer cells ability to grow, move and spread, and eventually lead to their isolation and destruction. One area of research that is showing great promise is called Monoclonal antibodies.
Monoclonal antibodies first entered research in the early 1980s to treat non-Hodgkin’s lymphoma. Since that time, researchers have made great strides using these targeted therapies in cancer treatment. These treatments began by identifying which therapies may prove useful. This process, known as biomarker identification, is the identification of antigens that uniquely present on the surface of cancer cells. One of the promising monoclonal antibodies in fighting breast cancer functions by recognizing a human epidermal growth factor receptor 2 (HER2) protein. HER2 is an oncogene that can transform a cell into a tumor cell and is amplified in 20-30% of early stage breast cancers. Thus, breast cancer patients treated with HER2- targeted antibodies can improve disease-free survival rates.
Unfortunately, no one treatment is effective for every cancer, or every person. Therefore, research in targeted therapies is critical and life-saving.