Doctors have new ways of obtaining non-invasive biological images, and may soon be able to customize treatments for various types of cancer.
By SUSAN DE LA FUENTEPublished: DECEMBER 28, 2006 12:48Advertisement
Cancer is the second leading cause of death in the western world, after heart disease, and it is encouraging to hear of advances in diagnosis and treatment. Even if the disease can only be 'managed' and not cured in many cases, any improvement in patients' quality - and length - of life is advantageous.
Chicago-born Dr. Thomas Tichler, chief of the Oncology In-Patient Department of the Davidoff Cancer Center in Petach Tikva's Rabin Medical Center, gave Metro an overview of some recent developments in the field. He spoke first of MRI (magnetic resonance imaging) diagnostic techniques that use magnetic field and radio frequency waves to obtain non-invasive biological images.
MRI is the best imaging technique to assess problems associated with soft tissues, he explained. "The most exciting development in the diagnosis and treatment of cancer concerns Diffusion MRI, now in experimental use in Israel. It enables us to perform accurate testing before and after chemo
therapy treatments. We can ac
curately predict response to treat
ment after the first chemo
therapy dose and, if necessary, immediately switch the patient to a therapy that may be more effective. In the past it took time to find out whe
ther the tumor was responding or not. The patient had to undergo three intravenous chemo treatments and endure harsh side effects - a process of up to nine weeks."
Tichler noted the value of MRI spectroscopy, a method that informs the physician of amino-acid levels in tissues. "Different types of organs have a different make-up of amino-acids in their cells. Levels of amino-acids, such as choline, creatine and citrate, show if there is a malignancy or not and inform us of its sub-type. We need to know the location and extent of the disease and whether it has spread. As MRI spectroscopy is noninvasive, there is no need for a biopsy. This advanced technique is being tested in the USA, and once funds are raised we will be able to use it in Israel."
What impact do advances in genetics and computerization have on clinical treatment?
"A key factor here is the genetic testing of tissues. The word 'cancer' covers a thousand different diseases and major categories like colon, lung and breast cancer are treated in different ways. The phenomenon of sub-types of cancer was discovered 50 to 60 years ago, and subsequently hundreds of subgroups were revealed. Today, thanks to computerized genetic advances, which reveal varied mutations of patients' genes, we have moved away from microscopic diagnosis to molecular diagnosis."
Determining the genetic composition of cancers enables a more accurate evaluation of the tumor, enabling customized treatments. "We can now tell which patients will respond to a particular treatment. In the past we knew that 40 percent of patients would respond to a colon cancer treatment and 60% would not, but we did not know which individuals would respond. Consequently, the treatment was given to all patients. Nowadays we can get a more exact cell diagnosis and identify the subtype of cancer."
What does this mean clinically?
"In the near future, doctors will know the genetic composition of the tumor before treatment, be able to gauge in advance the patient's ability to respond and select the best therapy to repair their damaged DNA. The genomics era is one of molecular biology, and micro-chip array technology is progressing rapidly in the US and exists here in Israel too. Computer chips can analyze human cells after a thin needle suctions out a few cells for analysis. This less invasive method spares patients the discomfort of conventional biopsy. Molecular diagnosis has produced an improvement in treatment, so doctors can now accurately forecast a patient's response to a particular therapy."
What are some of the innovations in cancer treatment?
"The main treatment remains surgery, and it has the highest rate of cure. It is crucial for the patient to come in when the tumor is still localized. Surgical techniques have improved significantly to the point that many a tumor, especially inside the abdomen, can be removed by laparoscopic (or keyhole) surgery. The patient can go home the following day instead of spending two weeks in hospital."
"Another significant advance is the computerization of radiation therapy. Radiotherapy uses high energy waves (x-rays) to treat localized cancer. When we expose the tumor to high doses of radiation, it's like shooting bullets to kill the malignant cells on the spot. The problem is that radiation can also kill normal cells around the tumor and cause considerable damage. Therefore it's im
portant that the borders of the radiation therapy should be exact, neither too narrow so that cancerous cells escape the bombardment, nor too wide. We now use a collimated machine with sliding lead leaves (called a LINAC or linear accelerator) that is computer-guided to fit the exact shape of the tumor. We also use IMRT - intensity modulated radiotherapy - in which the central part of the cancer receives the highest dose and the surrounding area of tissue gets a lower dose."
The inception of chemotherapy began with the German-Jewish Nobel Prize winner Paul Ehrlich, who died at the outbreak of World War I. "Ehrlich tested different chemicals to see which ones would kill particular bacteria. In the US, the National Cancer Institute tests about 15,000 synthetic and 400 natural products each year. Of these, 500-1,000 reach the level of testing on mice, 1/4,000 reach human testing and 1/40,000 human clinical use.
Clinical trials on humans are an involved and painstaking process. New drugs have now led to an improvement in patient response rate and increased survival. Chemotherapy regimens are being improved and now work in conjunction with radiotherapy and biotherapy.
Biotherapy has a promising future, and can boost the body's immune system. We can produce identical or monoclonal antibodies to certain molecules that have gone haywire and multiplied in the cells. We use the antibodies as medications as they stimulate the immune system of the cancer patient. For example, tyrosine kinase inhibitors act as a blocker that prevents the growth of tumors, and cancerous cells actually die. The advantage is that it has almost no side-effects, but it rarely works alone. There have been favorable results in recent years. Over the past six years, a combination treatment given to metastatic colon cancer patients attained an unprecedented response rate of 55-60% and improved average survival rates to 18-24 months, up from 12-14 months in the previous decade."
Can you suggest some preventive measures?
"It is advisable to undergo recommended screening procedures, such as pap smears and mammography for women. If there is a family history of bowel cancer, ask your physician which tests he recommends. Smoking, unfortunately, remains the number one cause of major illness. Staying out of the sun - especially in one's early years - will protect against skin cancer. Aim for a healthy diet, in which saturated and trans fats are avoided. These are also significant for heart disease. Charcoal broiled and smoked meat has also been implicated as a cancer risk when consumed often. The public should also be aware of environmental hazards such as asbestos."
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