For newly diagnosed cancer patients, the fear of radiation therapy can sometimes be as intense as  – or worse than –  fear of cancer itself.  In my practice, I try to explain to patients how some of the myths around radiation therapy can be misleading. Below are some of the most common fears and misperceptions:

"I don't understand how radiation works."  
The target of radiation therapy is cancer – whatever can be seen and also whatever is suspected (i.e. microscopic disease) – and its DNA. Ionizing radiation waves and particles can result in lethal DNA damage within a cell.
If a cell tries to replicate itself (which is what cancer cells do in an uncontrolled, unregulated manner) before it repairs this lethal DNA damage, the cell should die in the process. Some of the cells may die simply from the direct hit.

"Radiation will burn the tumor."
Contrary to common belief, radiation does not work by heating or burning the cancer. For one thing, radiation is not heat – a radiation treatment raises the body's temperature by about one-fifth of one degree. It's also not the same as a sunburn and whether or not you sunburn easily does not predict how you'll react to radiation.

"Radiation is invisible and so you can't control the damage it will do to me."  
Radiation is invisible: it's also painless, odorless and silent, other than the sounds of the machinery used to deliver it. And there are certainly dangers to radiation if placed in the wrong or inexperienced hands.

Recognizing this, radiation oncologists respect the power of radiation, what it can achieve in terms of cancer control or cure, and what it can damage if not applied correctly. The goal of a thoughtful radiation treatment plan is to deliver as much cancer-killing radiation as needed to  known or suspected areas of cancer while simultaneously maintaining the safety of the nearby organs.

"My neighbor got radiation and he had terrible side effects, so I know that's going to happen to me."  
Well-meaning friends, family and acquaintances will often share personal cancer-related experiences in an effort to be helpful and empathetic. But while every person is unique, so is his or her cancer, and although there are generalizations we can make based on tumor type (i.e. breast, lung, colon) and stage (i.e. early, advanced), we also know that there are genetic and molecular signatures that make each clinical case distinct.

And as each case is unique, so is every radiation plan. The side effects caused by radiation relate directly to the body parts that are exposed; controlling what needs to be exposed and what doesn't through careful radiation treatment planning helps to minimize side effects. But symptom development is also influenced by individual tolerance, which can be unpredictable and requires regular and careful monitoring to manage side effects.

"Once I get radiation, I can never have it again."  
 It is true that there are lifetime radiation doses that you would not want to exceed for a given person, and these maximums vary from organ to organ (different for the spinal cord than for the heart, etc.). But the ability to re-treat a cancer patient with radiation depends on many factors including how much of a radiation dose was given before, how long ago, and to what body parts. It's a complicated decision that involves a risk-benefit analysis of the current status and location of the cancer, alternative therapy options, and a patient's wishes.

Neha Vapiwala is a Vice Chair of Education, Radiation Oncology and the Advisory Dean at the Perelman School of Medicine at the University of Pennsylvania.  

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