February 07, 2011

Radiation and its health Effects

The radiation side effects experienced by the normal body tissues during and after radiotherapy can be loosely divided into Acute and Late effects.
Acute radiation side effects constitute the acute reaction occurring during radiation and in the immediate weeks and months following treatment.

Acute Radiation Side Effects

Radiation treatment is painless and without sensation, with the exception of some mechanical sounds produced by the treatment machine associated with the start and finish of the treatment. Many patients receiving radiation therapy will experience very little reaction, but in most the normal tissues will develop some degree of radiation reaction. This varies in amount and type, depending on the part of the body treated and the amount of normal tissue included in the radiation treatment.
The degree to which individuals experience reaction varies considerably, but this section will deal with some general principles of radiation reaction. Where large areas of a patient are treated, such as the whole abdomen or chest, the reaction experienced will be mainly of a general nature. When small areas are treated the reaction will be confined to that area of the body that is radiated and to the individual tissues included in the treatment volume. Any general reaction will be much less or absent altogether.
General Side Effect Symptoms
Radiation Nausea. The degree to which patients experience nausea following treatment is very variable. Some people will experience hardly any at all, whereas others will be troubled by nausea or vomiting during the early part of the treatment and, in some instances, throughout the treatment. If it occurs, nausea is likely to be worst from two to several hours after treatment. The patient should be encouraged to maintain fluid intake.
The following dietary steps may prove helpful:
1.Salty foods or ice cold drinks help control nausea
2.Avoid greasy foods, strong-smelling or overly sweet foods
3.Small, frequent meals eaten slowly
If insufficient, anti-nausea medication may be prescribed. In most patients nausea improves as the treatment progresses.

Hair Loss. Hair loss will only occur within the radiation field. Scalp hair will only be affected if the head receives radiation.

Fatigue / Malaise. Some degree of tiredness and lack of energy is often experienced. This will not prevent most people from working or undertaking normal duties but, in some, reduction in activities during treatment and immediately afterwards will be advised.

Low Blood Count. Reduction in certain elements of the blood is often seen following radiation therapy. This results from radiation exposure of bone marrow, and to a lesser extent, direct damage to lymphocytes in the blood stream and lymph nodes.

The white cell count will be reduced, particularly the lymphocyte count, and the number of platelets will be reduced. These drops are seldom enough to cause clinical problems, but if they are, an interruption in treatment for a few days is usually sufficient to allow recovery. Reduction in red cells does not occur to any degree in radiation treatment, but may occur from blood loss due to bleeding.
Changes in the peripheral blood count are much more marked in patients who have also received chemotherapy.

Organ Specific Side Effect Symptoms
Localized reactions will occur in any tissues exposed to radiation treatment. The acute reactions expected for different treatments will be considered later, but in general acute reactions result from radiation of skin, mucous membranes and accessory glands.

Skin. Where the skin receives a significant dose of radiation a reaction will 
develop which progresses through erythema to dry desquamation and moist desquamation. The reaction may only progress part way through these steps and healing occurs through the same steps in reverse. If desquamation has occurred, crusts will form which protect the re-epithelialisation occurring underneath and will only come away and not reform when the skin is healed underneath.

The reaction develops two or three weeks after the initiation of treatment and may take four to six weeks to heal. It is best managed by:
  1. Avoiding irritation from clothing, deodorants, perfumes, heat, dust and trauma
  2. Best of all, leaving the area open to the air
  3. Using non-stick dressings
  4. Opinions vary about moisture. If the area is bathed, dry carefully, do not rub or inflame with soaps, and dust with corn starch
  5. Steroid creams may help
  6. Hair loss may be temporary or permanent, depending on the amount of radiation. Hair loss only occurs in skin exposed to radiation treatment
  7. Avoid direct sunlight on the treated area
  8. Have patience, the reaction will heal
Mucous Membranes. Wherever mucous membranes are included in a radiation field similar reactions will be experienced: Whether in the mouth, pharynx, esophagus, trachea, bowel, bladder or rectum, mucositis may develop.
As with the skin, the mucosa is reddened at first but then may be covered with a plaque-like fibrin similar to crusting of the skin. The mucous membrane remains moist and the surface covered by fibrin until the underlying mucosa is healed, when the fibrinous plaque is lost and the reaction healed.
The symptoms resulting from the inflammation, irritation and dysfunction caused by the mucosal reaction depend on the site of the reaction. There may be discomfort and dysphagia or cough, hoarseness and tracheitis, or dysuria and frequency, or diarrhoea and abdominal cramps. The management varies from site to site, but depends on the same principles as the care of skin reaction.
  1. Avoid irritation by keeping food or stools soft and preventing trauma of any kind.
  2. Local analgesic mixtures, antibiotics where indicated, and steroids may help.
  3. Maintain hydration by encouragement and intravenous fluids if necessary.
  4. Low fibre diet for those with bowel reaction.
  5. Best of all, have patience, the reaction will heal.
Accessory Glands. The acute effects of radiation will be felt by accessory glands producing saliva and mucous for example. This leads to a degree of stickiness, leading to oral discomfort, dryness and change in taste, irritating cough and discomfort, and urinary or bowel symptoms, depending on the site of radiation.

Management consists of providing replacement lubricants such as frequent small drinks, adequate urinary and bowel fluid, cough suppressants, soothing creams or lotions and patience.

Late Radiation Side Effects

The late effects of radiation treatment develop gradually over several months or years. The changes that result may be sufficiently slight as to cause no clinical symptoms, or so rare as to present minimal risk to the individual. Nevertheless, the late changes that do occur warrant notice and care in all patients who have received radiation treatment. In those few individuals with serious late effects (generally less than 5% of patients who have received high-dose radiation) the results are often disastrous and treatment extremely difficult.

Scarring. Radiation treatment results in increased connective tissue, fibrosis and scarring often associated with atrophy of accessory tissues. This leads to some increased rigidity of tissues, less suppleness and less resistance to injury.

In addition, the walls of small blood vessels may be thickened and distorted, leading to reduction in blood supply to some tissues. This particularly leads to less ability to deal with injury or trauma such as that resulting from infection or surgery.

Any area of the body that has received radiation treatment should be treated "gently" for the rest of the patient's life.

Carcinogenicity. Radiation is one of the causes of cancer. Very rarely leukemia may result some five to twenty years after radiation exposure, due to bone marrow cells being damaged during radiation therapy. Similarly cancer can result in the area treated twenty or more years later.
The chances of either of these occurring are very small indeed.
The patient's risk of dying of the original disease, unless successfully treated, are much higher than the risk of developing cancer from the treatment.
Nevertheless, the risk is there and is one of the reasons why benign diseases are not treated by radiation unless absolutely necessary.

Genetic Effects. Exposure of the gonads to radiation increases the risk of abnormal mutations and genetic changes. Most chromosome damage from radiation results in a failure of conception and not an abnormal child. Even if both parents have been exposed to radiation, the risks of abnormal children being produced are so small as to be almost negligible. Late genetic effects in the individual are much less important than the increased risk of inducing cancer or the late vascular changes produced by radiation treatment.

  1. When a child or adult has cancer and is receiving treatment which may be suppressing their immune system, such as whole body irradiation, "live" vaccines should not be given until six months after treatment is completed- "Killed" vaccines may be given although it is unclear as to their effectiveness in the immunosuppressed patient.
  2. Immunosuppressed cancer patients should avoid changing diapers of infants or children for six weeks, who have recently been immunized with live (oral) polio vaccine. Immunosuppressed grand-parents are particularly at risk if they have never been immunized for polio. The risk is eliminated if the polio vaccine is given by injection (killed vaccine).
  3. There is no risk from "flu" vaccines as they are not live vaccines.
  4. Advice should be sought from the Infection Control Service or the Transplant Service of the Children's or Vancouver General Hospitals or family physician.
  5. Travel Immunizations: The same rules apply as in 1-2 above. 
Adapted from: Healthcastle Nutrition Inc.