Radiotherapy usually involves external irradiation of the patient with a precisely controlled X-ray source. It is used for both treatment and palliative therapy of cancer sufferers. This article looks at what a tumor is and how radiation can be used to treat it and the complications of radiotherapy.
The Legacy Of Hiroshima
One of life’s little ironies is that when people are asked about their objections to the use of nuclear power, the fear of cancers caused by radiation will come at the top of the list. The fear is borne of the horrors that many of the survivors from the two atomic bomb attacks on Hiroshima and Nagasaki had to endure; many victims who survived the initial attack died prematurely from cancer in the subsequent years. The vast majority of the victims of these attacks died instantly; not because of radiation poisoning, but as a direct result of the enormous explosive force of the weapons and the intense heat that was produced when they detonated. At very high doses, radiation can cause changes in DNA and the damage may result in the formation of cancers. However, at carefully controlled doses, radiation can be used to treat cancers that arise in people. Ionising radiation is, indeed, a vital tool for diagnosis and treatment of the injured and sick.
What Is A Cancer?
All cells have a finite lifespan and are constantly being replaced by our bodies. A cancer is caused when the mechanism that the body utilises to renew its cells breaks down, due to damage to the cell’s DNA. The cells start to replicate themselves in an uncontrolled fashion; older cells may not die as they should (via a process called apoptosis) and new, un-needed cells are also produced. Malignant cancers can spread to distant parts of the body and invade other tissues remote from the site of the original disease.
Radiotherapy can be used to treat certain cancers as a primary means of cure. In other cases, the technique can be used in combination with other treatments such as a surgical intervention, to remove as much of the tumour mass as possible, and chemotherapy. Radiotherapy may also be used in the terminally ill patient for palliative (pain relief) reasons. External radiotherapy involves irradiating the cancerous mass with a precisely controlled, targeted beam of X-rays produced from a machine called a linear accelerator (X-ray generator). In some instances, radiotherapy may be given internally as a cocktail that contains a radiopharmaceutical compound (a drug which incorporates a radioisotope).
The basis of radiotherapy is that cancer cells are dividing much more rapidly than normal cells and that by triggering further damage to the tumour cells DNA during the replication process, the patient’s body will either recognise these cells as alien and destroy them, or the cells will lose their ability to replicate. Normal tissue replicates itself more slowly than cancerous cells do and so it is less likely to be affected by treatment which, of course, could be one of the complications of radiotherapy: damage to healthy tissue.
Of course, women do sometimes have other conditions within their bodies where healthy cells are reproducing very rapidly: during pregnancy. Since there is a danger that radiotherapy could harm the developing foetus because of this very rapid cellular growth, radiotherapy is usually incompatible with an on-going pregnancy.
Complications of radiotherapy may include damage to healthy adjacent tissues; it is estimated that up to 15% of lung tissue may become permanently damaged as a result of radiotherapy for breast cancer – breast cancer is the second highest cause of death in women from cancers (behind lung cancer); so this trade-off may be very worthwhile. Other complications depend on the organ being treated but can include skin problems (redness, peeling, dryness etc); loss of taste; stomach pain; immune suppression; blood disorders; chest problems (cough or shortness of breath and inflammation of lung tissue).
It is crucial that the doses of radiation a patient receives are accurately administered and that the equipment used is properly calibrated and used by a radiographer. Modern radiotherapy machines can provide precise spatial control and exact doses of radiation. The patient will usually be required to wear shielding to restrict the possibility of radiation damage to healthy tissues. Despite the potential complications, radiotherapy is a valuable technique which can cure some cancers alone or in combination with other treatment and provide palliative care for the terminally ill cancer sufferer.
- Cancer Active, A simple guide to radiotherapy: http://www.canceractive.com/cancer-active-page-link.aspx?n=261
- National Cancer Institute, Defining Cancer: http://www.cancer.gov/cancertopics/what-is-cancer
- Cancer Research UK, Breast Cancer Statistics: http://info.cancerresearchuk.org/cancerstats/types/breast/
- Patient UK, Radiotherapy: http://www.patient.co.uk/doctor/Radiotherapy-What-GPs-need-to-Know.htm