One of the risks of radiation therapy is that radiation will kill the tumor but induce another cancer elsewhere in the body. This happens when tissue nearby the tumor either is in the path of the treatment beams or receives dose from radiation that gets scattered. Fortunately, the risk is often very low and any cancers induced will only appear years later. Still, as the chances of long term survival for cancer patients increase, this risk is something we take very seriously, and we do everything we can to minimize the dose that normal (non tumor) tissue receives. In any event, the benefit from receiving radiation therapy greatly outweighs the added risk of a secondary cancer. This is why this article from Natural News is so galling. It focuses entirely on the small risk of developing a secondary cancer without comparing it to the substantial benefit of radiation therapy.
The article describes a paper in the Journal of Clinical Oncology from a group of researchers from the Netherlands. They looked at women who had been treated for cancer in one breast to see how many later developed cancer in the other (called the contralateral) breast. Women who have had cancer in one breast are at a much higher risk to develop a second cancer primarily due to the same risk factors like genetics and hormone levels that led to the first. Their risk is about three to four times higher than the overall breast cancer risk. However, the amount of that risk that is a result of previous radiation therapy is controversial. Some studies have shown an elevated risk while others have shown no additional risk. Drs. Haffty, Buchholz and Perez in Perez and Brady (the bible of radiation oncology) state
Although there is some evidence suggesting a slight excess risk in women who are irradiated at a relatively young age (i.e., < 45 years at diagnosis), the risk is extremely small and may be related to older techniques, and most experts would agree that the benefit of radiation far outweighs the risk.
The older techniques mentioned in that quote refer to techniques that increase the amount of radiation that is scattered away from the breast being treated and can increase the dose to the contralateral breast. The traditional method for treating breast cancer with radiation involves irradiating the entire breast with two beams coming at the patient from different angles. These angles are referred to as “tangents” since they skim across the surface of the thorax at tangential angles. Often, devices called wedges were used to shape the fields. Wedges are literal wedges of lead or other attenuating material placed in the beam to lower the dose on one side of the field relative to the other. One of the acute side effects of radiation for breast cancer can be a burn to the skin. Wedges help to even out the dose and protect the skin.
However, wedges also cause radiation to be scattered away from the breast being treated. This scattered radiation can end up in the lungs, the heart or in the contralateral breast. As the techniques for treating patients have improved, we have started to move away from the traditional tangential treatments with physical wedges. There are several methods used today to shape the dose now that do not have the disadvantage of large amounts of scattered dose. So even if there were a risk of a secondary breast cancer in the past, future treatments should have a lower risk. However, any possible risk is still taken into account when planning a patient’s treatment, and techniques to reduce the scattered dose are used whenever possible.
The Dutch study found that there was a small increase in the risk of secondary breast cancer from radiation, particularly in the case of women who have a strong family history of breast cancer. This is an important data point in the discussion of therapy risks. The article on Natural News, however, blows it way out of proportion. The headline “Radiation Treatment for Breast Cancer Causes Cancer in the Other Breast” is hyperbolic. A more accurate headline would have been “Radiation Treatment May Increase Risk for a Second Cancer in Some Younger Women.” The added risk for women beyond 45 years old at time of treatment was not statistically significant. Women younger than 45 saw about a 50% increase in risk.
The article itself is actually a fairly good summary of the study, but the headline is unnecessarily inflammatory. The benefits from radiation therapy far outweigh any additional risk of a secondary cancer that may take a decade or more to appear. The field of radiation oncology is already taking steps to decrease any risk even more. The effect of the article is to inflate fears about radiation that women may already have and to scare them away from seeking conventional treatment for their cancer. Unfortunately, that was likely the intent. Other blogs have pointed out that scaremongering about modern medicine seems to be the whole purpose of Natural News. Hopefully, anyone who takes the time to actually read the study will see through the scare tactics.
