Radiation and Cancer
by Dr Denise Adams, GP in BMJ 2002;324:121
Personal View. Blast from the Past: A Cautionary Tale
When I was 41 I discovered that I had hyperparathyroidism and papillary carcinoma of the thyroid. Three years later I was treated for breast cancer. Fortunately I was cured of both cancers. However, as a consequence of the treatment I developed a debilitating proximal myopathy and have been left with poor control of my calcium metabolism caused by lack of parathyroid hormone. People tend to assume that I must have "bad genes," but unpalatable as it is there was an avoidable cause for all these illnesses.
Remember that there is no dose of radiation that is risk-free
I was born in the United States in 1955 and by the age of 4 months had developed a strawberry naevus on my neck. I had a series of radiation treatments to my birthmark during the following year. The decision to treat me was not based on good evidence and was made within a culture that believed radiotherapy was safe and effective despite accumulating evidence to the contrary. The fact that my birthmark was a benign, self-limiting condition seems to have been forgotten or not known.
I was in my late teens when I became aware that I was at increased risk of thyroid cancer because of the radiation treatment. I did not know about the risk of Hyperparathyroidism until I searched the Internet in 1996. I did not seriously consider that I was at increased risk of breast cancer, although I suspected that I might be, given the evidence that was accumulating about the increased risk of breast cancer in women who had been treated for Hodgkin's disease, particularly if they had been younger than 15 at the time. However, because the dose used to treat Hodgkin's disease was magnitudes greater than the dose that I had received, I really could not imagine that my risk was much increased.
People are shocked to hear that treatment for a benign condition could have had such terrible consequences. Many could not believe that it had taken more than 40 years for me to develop these cancers. This has led me to realize that more doctors than I thought only pay lip service to the dangers of radiation. To its credit the medical profession has taken heed of the evidence over the years and significantly reduced exposure to radiation during investigations, and treatments of the type I received are no longer recommended.
Everyone seems to know that exposure to radiation causes cancer, but do doctors bear this in mind every time they request a radiological investigation? I am not convinced that they fully consider the age of the patient and the risk that radiation carries, particularly to young people who have many years ahead of them in which to develop cancers. Do we always consider which investigation will be the lowest risk for a patient for the greatest diagnostic gain? For instance, spinal radiography, computed tomography, barium enemas, and angiographies expose our patients to higher doses of radiation than we might think. Do we remember that many patients have more than one radiological investigation and doses of radiation are cumulative? Do we constantly ask ourselves if the investigation is necessary or could be done by other means without exposure to radiation? Do health workers and others in radiation related work always take notice of the safety measures developed to protect them? I suspect not. It is hard to remember the dangers of radiation when it cannot be felt and causes no immediate harm at low dose.
It is hard to imagine that exposure today can result in cancer 40 or more years later. My total dose of radiation was considerably greater than that given in a single radiological investigation, and many people will console themselves with the fact that an x ray usually involves only a small dose of radiation and is therefore of no consequence. There is a tendency to seek refuge in the knowledge that a low dose of radiation carries little risk of causing cancer. This is true, but remember that although the risk may be low, there is no safe dose of radiation.
My case is exceptional and serves to illustrate that radiation really does cause cancer. As a consequence, it has impressed upon my colleagues and me the long-term dangers of radiation at low doses. I have welcomed the move by radiology departments to reduce doses of radiation and to inform doctors when they request inappropriate radiological investigations. However, there is still room to question our practice constantly and be vigilant about the use of radiological investigations. There is no doubt that radiological investigations have and will benefit many patients who would have been harmed by their illnesses without them, but when considering the risks and benefits of a test, remember that there is no dose of radiation that is risk-free. By minimizing exposure to radiation, particularly to children and young adults, we can prevent cancers occurring. So when next requesting a radiological test, remember what happened to me and reconsider the options before finally signing the form.
Reprinted with permission from the BMJ,BMA House,Tavistock Square,London WC1H 9JR
Originally published: Br Med J 2002;324:121. Adams D – “Personal views. Blast from the past: a cautionary tale”.
© BMJ 2002