By Sarah Murnal
With cancer incidence predicted to increase by 50 per cent over the next 20 years, it makes sense to know a little bit more about the current treatments and developments on the horizon.
With around 200 different types of cancer affecting 4 out of 10 people at some point in their lives, finding an effective treatment for an individual’s particular cancer is no mean feat. Oral cancer has a higher proportion of deaths per number of cases than breast cancer, cervical cancer and skin melanoma and there has been little improvement in survival rates over the past 30 years. Chemotherapy and radiotherapy are now widely known as treatments for some forms of the disease, but little is known about the other treatments on offer and even less about cancer treatments in development.
Current treatments
There are many treatments currently available to treat different types of cancers. In summary, these include:
Biological therapy
This is where proteins produced by the body stimulate the body’s own defence mechanism to fight cancer cells
Haematopoietic growth factors
Proteins produced naturally in the body stimulate the bone marrow to make the different types of blood cells – e.g. white or red blood cells – to help the body fight infection
Stem cell and bone marrow transplants
These are used to treat leukaemias and allow the patient to receive higher doses of chemotherapy, to improve the chances of curing the disease
Individual hormonal drugs
These interfere with the production or action of particular hormones in the body that act as chemical messengers and help control the activity of cells and organs
Monoclonal antibodies
These are used to destroy some types of cancer cells, while causing little harm to normal cells
Photodynamic therapy
A new treatment involving a photosensitising agent that makes cells more sensitive to light and, by doing so, causes cancer cells to be destroyed when a laser light is directed on a cancerous area;
Surgery
Surgery is used to remove tumors and nearby tissues that may contain cancer cells; and finally,
Clinical trials
These test new treatments and explore new combinations of existing treatments or changes in the way they are given to make them more effective or to reduce side effects
Drugs in development
New drugs to treat cancer are constantly being tested and must undergo various stages of research in the form of clinical trials or studies. These are to pinpoint a safe dosage, to see what the side effects may be, and to find out which type of cancers they might be useful for. Four drugs currently undergoing development are:
Adept (Antibody Directed Enzyme Pro-drug Therapy)
Adept belongs to a new group of drugs called monoclonal antibodies. It is a type of targeted therapy, using a monoclonal antibody to carry an enzyme directly to cancer cells. A few hours after the antibody is given, the pro-drug is given. When this comes into contact with the enzyme, a reaction takes place, which activates the anti-cancer drug and destroys the cancer cells, leaving the healthy cells intact.
Iressa
Iressa is a man-made chemical. Early trials have shown that it can partially shrink cancer tumors in patients with advanced cancer who have already received standard treatments for their particular type of cancer. At the moment, although Iressa shows promise as treatment, researchers are trying to find out why the drug can reduce a tumor in size, but does not have a lasting effect. As a result, the tumor may increase in size again after a short time. Teams working on this drug are experimenting with dosages to try to improve its performance.
STI 571 (Glivec)
This drug, again, is man-made and undergoing clinical trials on patients with certain types of leukemia. It works by blocking the signals in cancer cells and preventing a series of chemical reactions that cause the cell to grow and divide. At the moment, STI 571 is not licensed for routine use and so is only available to those participating in clinical trials.
Thalidomide
Thalidomide was well known in the 1960s for its use in treating sickness during pregnancy, resulting in birth defects. These defects were caused by thalidomide’s ability to interfere with the development of new blood vessels. As a cancer treatment, researchers are hoping to use the drug to prevent cancers from developing new blood vessels, thereby starving the cancer of oxygen and nutrients and causing the tumor to shrink.
Scientific breakthroughs for treatment of oral cancer
Over the last 18 months, Smile-on has reported several scientific breakthroughs that are helping the fight against oral cancer. In August 2000, the latest trials on Foscan (medicated photodynamic therapy), manufactured by Scotia Pharmaceuticals, indicated that it might be a very important therapy in the treatment of head and neck cancer. Photodynamic therapy, see Current treatments above, uses light to activate light-sensitive drugs in the treatment of cancer and other diseases. Trials indicated that Foscan was an effective procedure with minimal morbidity and good cosmetic results.
Medical Solutions plc’s Fairfield DNA Ploidy System is a system capable of predicting whether a patient with oral leukoplakia is at risk of developing oral cancer. Digital imaging technology is used to analyse the cell nuclei from a biopsy of each patient and compute the amount of DNA per cell. Those with a normal amount of DNA per cell were found to have a low risk of developing cancer (97-per-cent survival rate), while those with white patches and abnormal amounts of DNA were at high risk (16 per cent survival rate).
Gene therapy continues to play an important role in medicine, no less so than in the treatment of cancer. Scientists recently found that 2 immune-system proteins – interleukins IL-2 and IL-12 – effectively fight oral tumours in mice, and scientists believe that this therapy holds great promise in the treatment of head and neck squamous-cell carcinoma in humans. Also, a new oncogene called GKLF was discovered last summer that may play a key part in the development of oral cancer. Researchers found that the expression of GKLF is unique to oral and breast cancer and tests found that when GKLF was over-expressed in mice, they developed the early changes of malignancy and, finally, overt cancer. Now, this new gene will be a therapeutic target for drug discovery and other treatment strategies.
Alternative treatments
New discoveries in the treatment of cancer do not only centre on conventional medicine. In our haste to get to grips with a cure for cancer, natural products may be overlooked and dismissed in the fight against such an aggressive disease.
In December, the Academy of General Dentistry reported that a new study had found that simply swishing green tea around the mouth halts the growth of new oral cancer cells and breaks down and kills existing oral cancer cells. The antioxidants (polyphenols) in the tea work to remove the free radicals or oxidants and prevent gene mutations, and as an added bonus, the polyphenols can kill cancerous cells without harming normal cells and inhibiting their growth. Similarly, a chemical found in tomatoes may prevent or treat oral cancer and one derived from soybeans has been found to shrink abnormal growths that lead to cancer. While these are not cures, their activity may in the future lead to therapies that compliment conventional treatment modalities.
Perhaps combining ancient remedies with Western scientific advances is the way forward to finding an effective cure for cancer. Combrestatin – a cancer-fighting drug made from the bark of an African tree – is performing with dramatic effects in tests. The active ingredient extracted from the bark attacks the blood vessels that grow with tumors, while leaving normal blood vessels alone.
