Jul 06, 2001 - 3:09 pm
Radiation Therapy Side Effects
The side effects of Radiation Therapy can be classified as Acute, Subacute
Acute reactions occur during the course of treatment and are temporary.
Subacute reactions generally develop one to three months after completion
Delayed reactions usally occur 6-24 months after completion of therapy.
Subacute and late effects of radiation on different organs.
In the months and years following exposure to large doses of
Neuropathy, a problem that sometimes occurs with chemotherapy treatment. It is damage to the nerves. It can occur from some chemotherapy drugs used in conventional cancer treatment.
There are three major goups of nerves in the human body, the peripheral nerves that carry information to and from the limbs, the nerves that supply the bowels and other internal organs, and the nerves of the head which connect to the ears, eyes, taste buds, etc. Nerves in any or all of these major groups can be affected by certain chemotherapy drugs.
Nerves are vulnerable to many kinds of damage. They can be damaged by certain cancers. This may be caused by the cancer cells producing a particular kind of biological agent that interferes with the function of the nerves. Sometimes, they can be damged by drugs used in chemotherapy treatment. The chemotherapy drugs that most likely cause nerve damage are the vinca alkaloids(vincristine, vindesine and vinblastine), platinum drugs(cisplatinum, carboplatinum) and the taxanes(taxol, taxotere). These drugs have the potential of interfering with nerve function.
You may notice symptoms in different areas of your body depending on which groups of nerves are affected. Symptoms in the hands and feet happen when peripheral nerve damage happens and are not rare with vinca alkaloids. The first sign of nerve damage is usually a feeling of tingling and numbness like what you experience when your foot goes to sleep after you've been sitting for a long time in an uncomfortable position. If the problem progresses further, it often produces weakness of the muscles, resulting in loss of strength at the wrist or the ankle. You will notice difficulty in doing up buttons and picking up coins. You may notice that you will tend to trip while walking up stairs or dragging your feet and tend to have a wide-based gait. In severe cases, the weakness may be so severe that you will need a wheelchair.
When the nerves in the bowel are affected, constipation is the earliest sign. In a few people, the abdomen becomes bloated with a distended bowel that is basically paralyzed. Some of the nerves in the head can also be affected. Platinum drugs can affect the auditory nerve and cause loss of hearing and tinnitus(ringing in the ears). Vision can very occasionally be affected.
A lot depends on how quickly your cancer treatment can be stopped. Sometimes the need for treatment is more urgent then the residual nerve damage. Sometimes, the balance between benefit from the drug and the side effect of nerve damage is more finely balanced.
Once treatment has been stopped, recovery is usually slow. It may take months to get even partial improvement and often there will be some residual impairment, either a motor weakness or a sensory numbness or both. Recovery is slower in the feet and legs than in the hands and arms.
There is no specific treatment that enhances nerve recovery. There are no drugs that will directly stimulate nerve regeneration or recovery. If you have severe and prolonged pain, then the pain may require narcotics often combined with antidepressants. In some cases, certain types of anticonvulsants would be helpful. Treatment options are subjects that you should discuss with your doctor, so you have accurate expectations of potential benefits and side effects.
Chemotherapy affects both normal and tumor cells. The effect on normal cells is the cause of side effects from chemotherapy. Some chemotherapy drugs do permeate(pass through) the blood brain barrier(the system that protects the brain from foreign substances like disease by blocking their passage from the blood). The group of drugs called nitrosoureas like Cisplatin, Cisplatinum or Carboplatin are such drugs and natural substances such as Taxol, also cross the barrier. Necrotizing Leukoencephalopathy is the form of diffuse white matter injury that follows chemotherapy, as well as a suppressed immune system.The body's immune system attacks and eliminates not only bacteria and other foreign substances but also cancer cells. Cancer cells are not foreign to the body but their biological function has been altered in that it doesn't respond to the body's normal mechanisms for controlling cell growth and reproduction. The abnormal cells can continue to grow, resulting in cancer. Much of the body's protection against cancer is carried out directly by cells of the immune system rather than by antibodies circulating in the bloodstream. Cancer is 100 times more likely to occur in people who take drugs that suppress the immune system than in people with normal immune systems.