Radiation Safety and Prostate Cancer

What is the Risk of Cancer with CT Scans?

The CT scan (also called CAT scan) uses computer tomography to produce a 3-dimensional image of the prostate and surrounding organs. CT scans rely on computer-reconstructed X-rays to give a cross-sectional view of the body. A CT scan through the pelvis reveals the distinct outline of the prostate. The CT scan is often combined or fused with other sophisticated imaging and diagnostic modalities, such as MRI scans, PET scans, and a number of dynamic contrast agents, including ultrasmall superparamagnetic iron oxide (USPIO). These fused imaging modalities represent the state of the art and have greatly enhanced our ability to safely diagnose and treat prostate cancer and many other diseases.

There are a number of doctors who have issued warnings about patients undergoing CT scans regularly during routine checkups, suggesting that a CT scan is not worth the risk of even such a small amount radiation exposure because it will lead to an increased risk of leukemia or other cancers. Some critics also suggest that CT scans are done primarily to increase financial revenues rather than benefit patients. We believe the case against CT scans is a myth that does not hold up to rigorous analysis of the evidence-based data.

What is the rationalization for CT scans causing cancer? According to this argument, the ionizing radiation of CT scans may hit a DNA strand and cause it to mutate and become cancerous (carcinogenic). There is also a secondary phenomenon involving oxygen molecules. What happens is the incident radiation particle comes in as a photon, and it hits the oxygen molecules and scatters the oxygen into free radicals, which in turn also hit DNA strands and can break those bonds or alter them.

Does this process actually cause damage to cells? Various media accounts have suggested that it does and have discouraged people from having CT scans, in much the same way the media has tried to discourage men from having PSA tests and women from having mammograms. We think this may be part of the reason we are now seeing so many men with advanced prostate cancer, because many men are avoiding PSA testing. Men are often reticent to talk about their health and their private parts and erectile dysfunction and so on. So when they are mistakenly informed that they don’t need PSA testing anymore, that the test will not benefit them, they often put off being tested until symptoms of the disease can no longer be ignored, giving prostate cancer the chance to become advanced and spread throughout the body.

It may be telling to compare some of the healthcare recommendations that we read in the media with the kind of healthcare that our U.S. presidents typically receive and the kinds of routine diagnostic testing they undergo. The former presidents appear to be blessed with longevity. Jimmy Carter is 95 years old and only recently facing a serious challenge with cancer. Reagan was 93 and suffered from Alzheimer’s when he passed away. He also had colorectal cancer that was picked up early through diagnostic testing. Likewise, Gerald Ford lived into his nineties. Most of our modern presidents have long lifespans despite the stresses they endure. One of the reasons for their longevity might well be the annual “executive physicals” that they receive.

The Mayo Clinic is famous for conducting executive physicals, which they offer to heads of state and CEOs of corporations. Our center also offers this kind of extensive physical on an annual basis to our patients. We don’t push that kind of physical examination on our patients, but we do offer it to them. And we also listen to the media and try to address what may be concerns, which is one reason that we obtained at great expense the latest generation of CT scanner technology. Our machine gives very low radiation exposure, with extremely high resolution. It delivers only 1 mSv (millisievert) of exposure to the body, which is very low compared to even the previous generation of CT scanning machines, which are still widely in use at other institutions and register about 5 mSv of radiation exposure.

The reality is that alarmist studies on CT scanning have been basing the data on what is called the “linear no-threshold model,” or LNT, which is now widely considered obsolete and erroneous. The linear no-threshold model has been used since the 1970s in radiation protection to quantify radiation exposure and set regulatory limits. The model assumes that the long-term, biological damage and cancer risk caused by ionizing radiation is directly proportional to the dose. The risk of low doses was extrapolated from the risk calculated at higher doses. According to this model, radiation is always deemed to be harmful with no safety threshold, that is, no mater how low the dose of radiation. The additive effect of radiation exposure over time with this model would mean that a series of very small exposures would have the same effect as one larger exposure. That kind of reasoning is more and more being challenged these days.

A former associate of Dr. Dattoli and member of the Dattoli Team until 2020, Dr. Joseph Kaminski contributed to a 2009 article that called into question the basic premises of the LNT model for determining the risk of low-dose radiation exposure (Tubiana M, Feinendegen LE, Yang C, Kaminski JM. The linear no-threshold relationship is inconsistent with radiation biologic and experimental data, Radiology. 2009 Apr; 251(1):13-22). That article concluded, “It is unethical to fuel anxiety with debatable hypotheses…A balance should be made between the risk, if any, of an x-ray examination and the medical information it provides…LNT was a useful model half a century ago. But current radiation protection concepts should be based on facts and on concepts consistent with current scientific results and not on opinions. Preconceived concepts impede progress; in the case of the LNT model, they have resulted in substantial medical, economic, and other societal harm.”

The findings of that study and others led the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) to issue new policy recommendations in 2014 that departed from the LNT model for exposure below background levels of radiation. The UNSCEAR report to the U.N. General Assembly stated that “the Scientific Committee does not recommend multiplying very low doses by large numbers of individuals to estimate numbers of radiation-induced health effects within a population exposed to incremental doses at levels equivalent to or lower than natural background levels.” Dr. Kaminski published a more recent study on this subject cited above (Kaminski CY, Replacing LNT: The Integrated LNT-Hormesis Model, Dose-Response, 2020, April-June).

A 2016 paper from the Fox Chase Cancer Center provides an accurate assessment on current policies regarding safety regulations and low dose ionizing radiation. The abstract reads in part:

There is considerable disagreement in the scientific community regarding the carcinogenicity of low-dose radiation (LDR), with publications supporting opposing points of view. However, major flaws have been identified in many of the publications claiming increased cancer risk from LDR. The data generally recognized as the most important for assessing radiation effects in humans, the atomic bomb survivor data, are often cited to raise LDR cancer concerns. However, these data no longer support the linear no-threshold (LNT) model after the 2012 update but are consistent with radiation hormesis” (Doss, M., “Future Radiation Protection Regulations,” Health Phys. 2016 Mar;110(3):274-5).

The discredited LNT model is what leads some researchers even today to continue making false assertion that CT scans expose patients to enough radiation to cause cancers. The state-of-the-art CT technology at our institution is constantly upgraded to alleviate patient concerns about CT scanning, however misplaced those concerns may have been because of media-driven distortions.

With that said, through the years we have had many patients with early stage lung cancers whose lives were saved thanks to early detection. Those would have been advanced cancers had we not diagnosed them early with CT scans. We have also seen similar early detection with CT scanning save the lives of patients with pancreatic, hepatic and renal cancers, and those patients would have surely died were it not for early diagnosis and treatment. And we have had patients with a host of other conditions like abdominal aneurysm that would have become life-threatening if we had not detected them with CT scans.

At our facility patients pay about $430 out of pocket for total body CT scans with our advanced machine. That’s about the copay they would have to pay if they went elsewhere and had CT scans on the older, less expensive scanners. So we are certainly not having patients undergo CT scans in order to generate a revenue stream, given that our expensive machine is not reimbursed any more than the other less expensive CT scanners that most other institutions utilize. We perform these scans only for the benefit of our patients.

When we find patients who have advanced prostate cancer, we perform advanced imaging including CT scanning to detect lymph node involement. We know exactly where to look and we know if those lymph nodes are enlarged, regressed, if they’ve come back, and so forth. That is all very important data that allows us to appropriately treat patients and in many cases save their lives.

One lab test that men receive with their executive physicals when they come to us each year is called a QCT-BMD bone density exam. This is an elaborate DEXA type scan which women get starting at age fifty, sometimes sooner. It is usually given when they are post-menopausal. We use this test in part because men actually have increased risk for osteoporosis and osteopenia much like women do. Interestingly when men develop hip fractures, for example, they have a twofold risk for that becoming a fatal injury. We often see men who are sedentary, who smoke cigarettes, who drink alcohol, who have a thyroid disorder or chronic GI distress, or undergo prolonged hormonal therapy, experience bone mineral decline like women do.

What we do differently at our center is this. Women undergo what is called a DEXA scan. That scan is an excellent technique and a standard in endocrinology. Other institutions such as the National Osteoporosis Foundation suggest that all men starting at age fifty should be tested. We take this DEXA scan a step further. When a typical DEXA scan is done, we are looking at a cortical bone. That is the outside of the bone that you may think of when you see images of the skeleton. However, what the DEXA scan can’t measure is the inside of the bone, that is, the mushy, interior part of the bone where the bone marrow is.

With our scanner, we can measure that interior and it’s actually a forecast of what is going to be seen in the near future in terms of bone health or deterioration. In other words, the extra-skeletal bone is what it is; however, the marrow inside of the bone is a forecast of what the future of the bone will be. So we look at both the inside and outside and treat a patient accordingly, because if the trabeculae marrow is not healthy, that predicts that the outer bone is also going to be unhealthy in the future.

All of this care is expensive. A typical Dexa scanner may cost $50,000, but in order to do a QCT-BMD as well, we need an advanced CT scanner costing millions of dollars and the software program, which is hundreds of thousands of dollars. This is typically another part of the executive physical done at our institution when men choose to have it done. Again, this is an option for them, and we aren’t trying to push it on our patients. But many of our men are pretty savvy and already having annual executive physicals. Many were or are among the best and brightest of CEOs and other leading professionals in their fields, and they are accustomed to having this standard of care each year and simply want to have the scan done.

As mentioned, with our CT scanner, patients receive 1.0 mSv of radiation. If you take a flight from New York to London, you are exposed to more radiation in your body than a CT scan. So if you do a lot of traveling, you are essentially getting the equivalent of multiple CT scans. And what about the pilots? What about the flight crew? In fact, because of their exposure to cosmic rays at high altitudes, they are exposed to a higher radiation dose than nuclear power plant workers. Are pilots and flight crews and their unions concerned about their safety? Are they being tested for leukemia and other potential secondary malignancies? No, they are not, because the risk is negligible or simply nonexistent.

It would be absurd for us to warn pilots about a danger that in reality does not exist. If we had ever heard about pilots or flight attendants being diagnosed with cancer at an alarming rate, we would know that by now. Obviously, commercial airplanes and their crews have been around quite a long time.

Radiologists are working with ionizing radiation all the time. What about radiation technologists? What about cardiologists? What about the physicians at our center? We are exposed to relatively high doses by just handling the radioactive seeds that we use for brachytherapy. We receive far more radiation than a CT scan imparts, and we have had that kind of exposure over many years without being at risk for radiation-induced cancers.

The people who were exposed to the atomic bomb at Hiroshima and Nagasaki have been well tracked over the years since the time of the bombing. There was a group around the perimeter that did get very high, toxic doses and died from radiation poisoning and toxicity. But many others just outside the perimeter didn’t. What they were subject to and harmed by was fire, not radiation. They were breathing contaminated air and eating contaminated food and they may have had an increase in carcinogenic levels, as did victims of the Holocaust, from the poor nutrition and stress they lived in. They had a higher risk, but they didn’t suffer from any radiation poisoning.

Likewise, the 9/11 victims who were in close proximity of that disaster have also been tracked. Many of them have developed cancers in the years since. But they were not radiated; they were simply in harm’s way and breathed in toxic fumes. So people living in that general vicinity of downtown New York City are being followed, and they have had an increase of developing malignancies, especially firefighters, compared to the rest of the population at large, not because of radiation but because of other risk factors, like stress, bad air, toxic fumes.

Chernobyl is another illustrative case. There were people who were in the perimeter and about two-dozen people did die from radiation poisoning. But outside of that pool of patients, the number of radiation casualties was extremely low. About 200,000 people were evacuated from that catastrophe and never came back, even though it’s a very popular destination today for tourists! There were as many as 1,250 suicides because of the radiation scare after the event, with many people fearing that they were doomed to develop cancer after exposure. 200,000 women had abortions after Chernobyl because of that kind of psychological terror. Indeed, the risk of low-level radiation was far more psychological than physiological.

A 2005 study reported that “the mental health impact of Chernobyl is the largest public health problem unleashed by the accident to date” (Andrew C. Revkin, “Nuclear Risk and Fear, from Hiroshima to Fukushima,” New York Times, March 10, 2012) In fact, there was a small cancer risk for people who were close to the perimeter at Chernobyl, but the risk was thyroid cancer, which is very curable.

So we believe only much greater doses can cause cancers, because very high doses of radiation can overwhelm what is known as “natural DNA repair.” We are all walking, breathing DNA repair machines. We have discussed ionizing radiation and oxygen. All living organisms have been subject to DNA radicals being shot out from oxygen and have learned to repair the damage. There are repair mechanisms of action in the body that actually appear to reduce the rate of cancer. This has been going on since the first appearance of organic molecules. We believe the process of DNA repair has actually perfected itself to the point where people who have been subjected to cumulative low doses of radiation, like those living at high altitudes, have a very low incidence of cancer.

The longest-living people in the world are those who live in the Himalayas and they have a lower risk of developing cancers than those of us living at lower altitudes – as much as 30% lower risk. So DNA repair suggests that low dose radiation may actually be good for you. This theory is known as “radiation hormesis.” It is predicated on the protective ways that our bodies cope with radiation and repair damage, taking care of mutant cells and not allowing their progression. Proponents of hormesis argue that low doses of ionizing radiation within or slightly above natural background levels are beneficial, because the radiation stimulates the activation of DNA repair mechanisms that protect us against cancer.

According to this theory, DNA repair mechanisms are effective enough to reverse the detrimental effects of low-dose ionizing radiation. It’s a repair mechanism that has been in place since the beginning of life and it’s only gotten better over time as our bodies have adapted. It’s an evolutionary adaptation that protects humans and all other species.

Given the available evidence and most recent studies, we believe radiation is certainly not toxic in low doses like that generated with CT scans. It is also telling perhaps that most healing springs have radiation in their waters. These springs probably expose us to the radiation of about ten CT scans done by the older generation of scanners without increased risk of cancer.

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Breaking News, May, 2020: According to a study from the University of Massachusetts, low dose Radiation Therapy may be a life-saving treatment for COVID-19 patients with pneumonia and acute respiratory distress syndrome (ARDS).
Click here to view this study

Breaking News, Oct, 2020: On the subject of treating coronavirus patients with low-dose radiation, Forbes Magazine published an article entitled, “COVID-19 Kills More Americans Every Week Than All Radiation Deaths In World History.”
Click here to view this study.