Radiation Safety and Prostate Cancer: Need You Be Concerned?

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Radiation Safety and Prostate Cancer: Need You Be Concerned?

By Michael J. Dattoli, M.D.

The use of radiation in medicine has a long history to which scientists from diverse fields, such as physics, chemistry, engineering and medicine, have contributed over many decades. It was through the pioneering research of Madame Marie Curie more than a century ago that the medical use of radiation, and X-rays in particular, first became a possibility. Our center is a part of that continuing history which allows us to provide our patients with the unique benefits of some of the most extraordinary advances of medical science in recent years.

Madame Curie’s pioneering work on the theory of radioactivity and her role in the discoveries of polonium and radium took place at a time when no one even realized that radiation carried with it health risks; and therefore, no one took precautions to prevent overexposure to radiation. Madame Curie’s death in 1934 was due to a form of aplastic anemia that had been caused by her many years of exposure to radioactive materials in the course of her research – she often carried test tubes of radium in her pockets. Ironically, her death occurred in the same year that her daughter, Irène Joliot-Curie, discovered what was called “induced” or “artificial” radioactivity, one of the early milestones in the field of nuclear medicine, which utilizes radionuclides (radioactive isotopes).

By 1946, radionuclides were being produced for medical use by the Oak Ridge National Laboratory. During the 1950s, the clinical use of nuclear medicine became widespread, as researchers increased our ability to detect and measure radioactivity and to use radionuclides to monitor biochemical processes. Many researchers in the U.S. and abroad worked to establish the efficacy, safety and therapeutic potential of this specialty. Over time, nuclear medicine has spawned a multifaceted industry that has progressed with countless remarkable technological innovations. The technical breakthroughs have been accompanied by the implementation of rigorous safety standards and strict regulatory oversight to ensure the safe use of radiation in medicine.

Radiation in various forms has multiple lifesaving applications in the diagnosis and treatment of many types of cancer, including prostate cancer as well as breast and lung cancers. In a clinical setting like that at our center, where we use the most sophisticated technologies currently available for the delivery of radiation, both the safety and efficacy of radiotherapy are augmented by patients coming to understand the basics of how radiation works and thereby feeling confident about the standard of care that they receive at our center.

As with all medical procedures, the safety of radiation is enhanced when patients are well informed about each particular test or course of therapy, and there is a very clear line of communication between patients and the medical team. Patients should be informed as to what specific radiopharmaceutical or what kind of radiation will be used in their treatment or diagnostic procedure. And they should also be aware of exactly what safety precautions may be required.

All radioisotopes have a “half-life,” which is how long the isotope takes to decay and become inert. Some patients may continue to emit detectable levels of radiation for periods of time after undergoing certain procedures or treatments. In those cases, precautions are taken. For example, some men may be advised to temporarily avoid prolonged exposure to young children, as is the case for prostate cancer patients who undergo brachytherapy, which is a mainstream procedure we offer that involves the implantation of radioactive seeds.

Patients who undergo certain nuclear medicine imaging procedures may require special preparation beforehand. For example, patients may need to stop taking some medications or follow certain dietary guidelines. At our center, the Dattoli Team provides advice about exactly what preparation may be required of patients prior to a particular test or procedure in order to ensure their safety.

Our current protocols for Dynamic Adaptive Radiotherapy (DART), which as noted is often combined with brachytherapy, utilize the latest cutting edge technologies for the diagnosis and treatment of prostate cancer. We have multiple, state-of-the-art systems in place to safeguard the patients under our care, as well as the doctors, nurses, technicians and support staff who comprise the Dattoli Team. We are ever vigilant in this regard and we do far more than is mandated by federal and state oversight regulations to ensure the safety of our patients. This standard of care has been achieved thanks in part to the breathtaking progress in recent decades with both advanced imaging modalities and radiation delivery systems.

Our innovative technologies are making diagnosis, management, and treatment of prostate cancer and other diseases more sensitive, more specific, more effective and ultimately safer. With diagnostic imaging, we have seen a growing popularity of fusing modalities, such as combining the metabolic imaging of positron emissions tomography (PET), computed tomography (CT) scans, and magnetic resonance imaging (MRI) scans. We are also taking advantage of the new role of therapeutic radiopharmaceuticals and contrast agents that use molecular targeting as a method of prostate cancer detection and localization, which can be either organ or tissue specific.

A radiopharmaceutical can be used for diagnostics or therapeutics, and can be administered to patients by injection, by inhalation, or orally. Once it has been administered, the chemical moves through the body to the specific organ or tissue to which it is attracted, before being metabolized and excreted from the body. As the chemical moves through the body, external devices can be utilized to detect the radiation it emits, which is used to generate computer images of the areas of interest and thereby locate cancerous lesions.

Because the targeted radiation only travels a short distance, damage to healthy neighboring tissue or organs is minimized. These tests can be performed on an outpatient basis and most patients can go home after the procedure.

We want to help our patients make informed decisions and enjoy peace of mind about their own choices with regard to both diagnostic laboratory tests and treatment procedures that utilize various forms of radiation. Many of our observations regarding the safety of diagnostic imaging and radiotherapy as they pertain to prostate cancer are also applicable to other cancers and diseases.

In our practice, the bottom line is that each diagnostic examination and each therapeutic procedure is conducted so the radiation dose to the patient is the lowest necessary to achieve our clinical aims. We share our patients’ concerns about safety in part because we find ourselves working in close proximity to radiation sources each day. Yet we know that our exposure as well as that of our patients is well within safe limits. The Dattoli Team recently published a peer-reviewed commentary on the historical and current criteria used to determined radiation safety, discussing the issues and technical concepts under the title, “Replacing LNT: The Integrated LNT-Hormesis Model.” Click here to view this article: (https://www.researchgate.net/publication/340653925_Replacing_LNT_The_Integrated LNT-Hormesis_Model).

We also know that the news media frequently misinforms the public about the risks of potential side effects from undergoing various procedures that utilize radiation, including radiological lab tests such as CT scans, which we will discuss below. There are a number of alarmist myths that continue to circulate on the Internet and elsewhere. This is not to say there are no risks involved with the various applications of nuclear medicine and radiotherapy; but the evidence-based data from many published studies demonstrates that the immense benefits for patients greatly outweigh the risks of any harm, including possible long-term radiation-induced side effects such as secondary cancers.

Prostate cancer is one of the most controversial fields of medicine, and physicians continue to disagree about which treatment options offer the greatest chance for cure with the least danger of side effects. We encourage all patients to become informed, to ask questions and to be proactive – to demand the highest standard of care. In the end, whatever you decide as you consult with your physician with regard to diagnostic testing and treatment, you should feel confident at the end of the day that you have made the right choices for yourself based on your own particular needs and individual case. We are devoted to helping each of our patients to achieve that level of confidence with the care that we provide.

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 seeing so many men with advanced prostate cancer, because many men are now 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. Some of our former presidents, like Jimmy Carter and Gerald Ford appear to have been blessed with longevity despite the stresses they have endures. 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 member of the Dattoli Team, 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.”

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 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 as much as several hundred dollars out of pocket for 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 centers 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 involvement. 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 CT-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 CT-BMD as well, we need an advanced CT scanner 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 stewardesses 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 whatsoever.

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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