Cancer treatment: yesterday, today and tomorrow

Few things can produce the level of fear that a cancer diagnosis can. Apart from possible death, the news has traditionally meant a tortuous path of treatment that, for many, is like parachuting into dense jungle without maps or a compass. But doctors are on the verge of significant breakthroughs that will change the way we think of this disease. As the future becomes the present, we can pin our hopes on ever more solid and effective cancer treatment – and prevention – options. 

When our grandmothers found lumps in their breasts in the 1950s, they were treated with an aggressive surgery called radical mastectomy. Surgeons removed the breast, the large chest wall muscles and the lymph glands in the armpit. After that, the patient couldn't lift her arm above her shoulder – and even with the surgery, her life was not prolonged. Few women survived more than five years. 

Twenty years later, when our mothers got breast cancer, the surgical option was less horrifying, and chemotherapy and radiotherapy were showing promise. Trouble was, the side-effects were terrible. Chemotherapy was distressingly toxic to all parts of the body, and radiotherapy sometimes meant painful burns on the chest wall.

How cancer treatment has changed
These three treatments -- surgery, chemotherapy and radiotherapy -- were summed up in the 1970s and '80s mantra Slash, Poison, Burn. It was the best doctors could do.

But in 1985 the New England Journal of Medicine published results of trials that showed that a less invasive surgery called lumpectomy was, in many cases, just as effective as a mastectomy, especially when combined with tailored radiation and chemotherapy. Today cancer is treated more precisely and with far fewer side-effects.

But what of the future? For most people with cancer, the future spells hope. Cancer treatment is on the cusp of a quantum change. Of course, some basic techniques will stay the same. Surgery will still be the first line for most cancer treatment, but thanks to the latest detailed imaging technology, surgery is no longer as radical, but rather is focused on precise tissue and, therefore, less extensive. In fact, preoperative imaging may uncover information that makes surgery unnecessary. At the same time, other cancer treatments are showing more and more promise. As these new technologies become available, the outlook after a cancer diagnosis will be radically different.

What is cancer?
All cells in the body grow, die and replace themselves constantly. But some cells manage to escape their innate control mechanisms. These are the cells that form abnormal new growths, known as cancer. Their continual, uncontrolled and disorganized development obstructs normal body functions, interferes with blood supply and destroys normal, healthy tissues.

Cancer is not a single disease. There are more than 200 different types of cancer, each with its own “fingerprint,” a unique combination of cellular patterns. Understanding the diversity of these fingerprints is one of the keys to developing new and effective treatments. Historically, Slash, Poison, Burn cancer treatments killed cancer cells, but at the cost of damaging or destroying healthy tissue as well. The latest research focuses on “targeted therapies” to attack and destroy only cancer cells.

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The future of cancer: customized treatments
Imagine your cancer specialist can identify the best treatment for you by studying the characteristics of your cancer cells and reviewing your genetic makeup. Sounds a bit futuristic? It is today, but scientific research is moving ever closer to making it a reality. 

Currently oncologists use well-researched methods to decide which cancer patients need chemotherapy and which don't. But uncertainties linger, and to resolve them, scientists are going to the heart of the matter – inside the genes themselves.  

Researchers at Duke University in Durham, N.C., have developed a genomic test that indicates which patients with early-stage lung cancer are likely to suffer a relapse. A genomic test is conducted on tissue samples removed at the time of surgery. Thousands of genes are scanned to measure the level of certain kinds of activity. The results help doctors make a highly accurate assessment of which patients are at high risk of cancer recurrence and should therefore undergo chemotherapy. A genomic test for breast cancer and the likelihood of its recurrence is now being developed.

Tomorrow's cancer cures
Tomorrow's cures will get right into our cells for precise healing by working with genes to weaken cancer cells from the inside; creating anticancer “viruses”; teaching the immune system to destroy cancer; or training tumours to die.

Your genes are cellular chemical structures – DNA – that direct your entire body's development and functioning. Gene therapy means using “engineered” genes to regulate or correct cell functioning. Genetic engineering involves extracting, manipulating and then reintroducing specific cellular DNA into a target cell to alter the way that cell functions.

In some cases, the goal is to stimulate the body's immune system to attack cancer cells, making them more susceptible to chemotherapy or radiotherapy. Manipulated genes are generally transferred back into cells by a carrier or “vector.” Vectors are specialized particles, often viruses, that are designed to invade cells and safely deliver the gene into specific cancer cells. Gene therapy is being intensively researched worldwide in order to find the safest way to use this therapeutic advance.

Viruses can themselves be engineered to kill cancer cells. Oncolytic viruses (onco means “cancer,” and lytic means “killing”) are used in an innovative cancer therapy called virotherapy.

In Canada, the Terry Fox Foundation, along with the Canadian Cancer Society, has been engineering viruses to kill brain cancer cells. Dr. William Wold and his colleagues at the St. Louis University School of Medicine have been at the forefront in engineering common cold and influenza adenoviruses to multiply only in the presence of certain cancer cells. The viruses then invade the cancer cells and reproduce so rapidly that the cancer cells burst and die. And, no, you don't get the flu as a byproduct, because the gene that causes the flu has been removed and replaced by genetic material encoded with the cancer-cell destroying effect.

This type of therapy has great potential; properly engineered viruses almost completely spare normal tissue. Even better, they can proliferate in the body for a long time, destroying all developing cancer cells and eliminating the need for traditional treatment repetitions. As well, there is evidence that some of these viral treatments work together with more conventional treatments, such as chemotherapy, producing – for poorly understood reasons – a synergistic effect that leads to better outcomes. Still, in spite of encouraging advances, it will be years before this technology can be used safely and effectively.

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In another field, scientists are researching ways of teaching the body's immune system to attack and destroy cancer cells. Leaders in the field include the Dana-Farber/Harvard Cancer Center, home of the Monoclonal Antibody Core, dedicated to the study of this technology. The immune system works like this: Foreign substances, called antigens, stimulate a “fight” response by the body's immune system. The body produces proteins, called antibodies, each of which locks on to its specific antigen, identifying it to the immune system as something that needs to be destroyed. In order to use this immune response against cancer cells, scientists have designed antibodies called monoclonal antibodies. Each can identify a single antigen in cancer cells, attach itself to that antigen and trigger that cell's destruction. 

The best known monoclonal antibody is Herceptin, approved since 1999 for use in women with a certain kind of breast cancer. Avastin, another monoclonal antibody, treats advanced colon cancer. As of August 2006, American companies had 160 different monoclonal antibodies, with a variety of applications, in clinical trials or awaiting government approval. 

In another strategy, adoptive immunotherapy, T cells, a type of white blood cell that is central to a healthy immune system, are taken from the patient and genetically programmed in such a way that, when returned to the patient, they will recognize, target and kill cancer cells.

A cancer treatment breakthrough
Just last year, both Canadian doctors in Toronto and Italian researchers in Rome announced a breakthrough discovery: not all cells in a tumour make the tumour grow and spread. Those that do, which the scientists are calling “cancer stem cells,” have a unique chemical profile. If doctors can engineer antibodies to attack these particular cells they might be able to kill cancer for good, with no chance of recurrence. 

In addition, doctors hope to tap into how our bodies naturally destroy diseased or damaged cells. Researchers have discovered that cancer cells may block the mechanisms that regulate this apoptosis, or programmed cell death, so that cancer cells are not getting the signal to die, but instead continue to grow and multiply. The proteins that cause programmed cell death have already been discovered. Now EpiCept Corporation in California is working with drugs that would mimic these proteins, to see if they would increase tumour cell death. This novel approach to targeted cancer treatment is in the early stages.

Cancer vaccines
When we think of vaccines, we think of preventing illnesses caused by viruses, such as polio or measles. The new cervical cancer vaccine works by preventing infection by the sexually transmitted human papillomavirus, which can cause cancer. But other cancer vaccines are a bit different. 

How do they work? Cancer cells have mechanisms to make themselves invisible to the body's immune system. Cancer vaccines are used to help the immune system recognize the tumour cells and then fight back against them. They are not preventive; they are administered after the cancer develops. 

Therapeutic vaccines have some advantages over standard cancer therapies: they are well tolerated and have few side-effects, thanks to the immune system's ability to attack only foreign cells. Scientists hope that they will produce longer remissions by triggering the immune system to remain on guard for longer periods of time. They might even prevent the cancer from ever coming back. 

Vaccines against breast, lung and ovarian cancers, as well as melanoma, are still in the experimental stage, and much work remains to be done. As with many cancer treatments, they will likely be used in conjunction with other therapies rather than as a stand-alone treatment. Huge strides are being made in progressive and humane ways to tackle cancer. We are on the verge of a radically new future, made possible by the dedication of many researchers, who hope that one day a cancer diagnosis will provoke no more fear than that of any other disease or sickness.

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This article was first published in the February/March 2007 issue of Homemakers Magazine. Click to subscribe online and never miss an issue.