The Forgotten Tool in the Fight Against Cancer
Advanced Oncology Center has state of the art equipment and offers various forms of radiation treatments for our patients.
In the fight against a cancer that has already been diagnosed, cancer specialists typically think of three main treatment modalities. However, most patients typically think of only two: surgery and chemotherapy. The treatment of less aggressive cancers may require only one of the three main treatment modalities. In certain cases, patients may even have a choice between equally effective treatment options. However, for more aggressive cancers, all three treatment methods are often required to achieve the best results.
In any case, it is extremely important for patients and their caregivers to understand all of the treatment options in order to make the most informed decisions to maximize the benefits of treatment, while minimizing the side effects. The third cancer treatment tool that is often forgotten in the fight against cancer is radiation therapy.
What is radiation?
For many people, the mention of radiation elicits fear and trepidation. Part of that fear comes from the fear of the unknown, as radiation is something that we do not see and we often cannot feel and yet we have been warned many times about its dangers. Disasters such as the Fukushima disaster in Japan last year further contribute to the apprehension that most people associate with radiation. The irony is that the opposite used to be true. One of the earliest pioneers in the field of radioactivity, Marie Curie, who still has a unit of radioactivity named after her, actually passed away in 1934 from complications due to excessive radiation exposure. As late as the 1950s, shoe salesmen were using X-ray machines in the middle of shoe stores in order to help assess the fitting of new shoes.
Some people believe that by avoiding these shoe fitting X-ray machines, or by refusing to take screening mammograms are chest X-rays, they are able to reduce their radiation exposure to 0. However, what many people are not aware of is that we are already exposed to radiation every day, from sources such as radon in the air as well as cosmic rays from space. Therefore, it is impossible for us to completely eliminate any radiation exposure and still go about our normal daily living. Fortunately, our bodies have adapted to be able to tolerate moderate amounts of radiation without undue consequences.
Over time, with more research we now better understand the dangers of radiation, and the general public has been warned of the dangers of excessive radiation. But more importantly, scientists also better understand the levels of radiation exposure that would actually be worrisome, as well as how we can harness the vast power of radiation to help promote health, rather than to compromise it. The radiation utilized in radiation therapy is typically high-energy photons, neutrons or charged particles directed towards cancer cells.
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How can radiation be beneficial?
On its most basic level, radiation works by damaging DNA in the cells of our bodies. As mentioned previously, our cells are already subjected to daily radiation exposure from natural background radiation. As a result, our normal cells had evolved to be very adept at repairing moderate amounts of DNA damage. Conversely, cancerous cells typically will have impaired DNA repair mechanisms, which are thought of as one of the reasons why those cells became cancerous in the first place.
Radiation therapy works by exploiting this difference between normal cells and cancerous cells. By damaging the DNA of cells in the areas of cancer, normal tissue will repair the DNA damage, as it does so millions of times throughout the day due to background radiation. However, cancer cells will have more difficulty repairing that damage, resulting in cell death or at least the permanent inability to further grow and divide. Once a cell has lost its ability to grow and divide, it would no longer be considered cancer.
In addition, cells that divide more rapidly (such as cancer cells) also tend to sustain more DNA damage as a result of radiation. Therefore, cancerous cells will sustain more DNA damage and have impaired abilities to repair that damage. The benefit of such a mechanism of action is that it is harder for cancer to develop a resistance to radiation, since all cells must contain DNA.
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How has radiation therapy evolved and improved?
Broadly, there are three main ways to deliver radiation therapy. 1) External beam radiation is delivered from outside the body using machines to generate and direct the beams of radiation. 2) Internal radiation therapy (commonly called brachytherapy) uses radioactive materials placed in or around target tissues to deliver radiation locally. 3) radioactive isotopes are ingested or injected into the body and may be attached to other substances to help concentrate that isotope in the target area or organ.
Many of the advances in external beam radiation therapy have been designed to focus more the radiation dose on the tumor cells, allowing for better sparing of normal tissue. Historically, radiation therapy has been delivered utilizing either two-dimensional or three-dimensional conventional treatment plans. This is performed by shaping the beams based on X-ray films or CT scan images. Beams can be shaped to conform to the projection of target from various treatment angles. This technique is well established and also to be faster than many other techniques, both in terms of generating a treatment plan, as well as treatment delivery. Even though this technique is limited in its ability to shape the beams and confine the dose of radiation to the target, it is an effective treatment delivery modality and still utilized in certain situations depending on the type and stage of the cancer.
The development of IMRT (Intensity Modulated Radiation Therapy) has been a significant advancement in the field of radiation oncology. Previously, physicians were able to shape the beam of radiation to conform to the shape of the target. With IMRT, not only can we shape the beam, but within each beam, we can adjust the intensity of different parts of each beam. Each beam is broken into very small beamlets, and the intensity of each beamlet can be adjusted with the computer planning. As a result, we are better able to focus the dose of radiation on our intended targets, while sparing normal tissue.
Various studies have demonstrated the superiority of IMRT for focusing dose on appropriate targets and sparing surrounding normal tissues. Clinically, improved focusing of dose has enabled dose escalation, which in turn has resulted in improved cure rates. Studies have also directly demonstrated that IMRT has effectively reduced side effects for patients undergoing radiation therapy.
IMRT is the technology which focuses the radiation doses. There are various machines that are designed to deliver this type of radiation, including Synergy, Infinity, Tomotherapy, TrueBeam, and Trilogy, to name a few. No clinical trials have been conducted to demonstrate whether any one of these is any better than another.
One of the issues associated with restricting the dose tightly around our targets is that accuracy becomes much more important. As a result, often times, treatments with IMRT are coupled with a complementary technology—Imaged Guided Radiation Therapy (IGRT). IGRT involves taking images prior to radiation delivery to ensure the accuracy of patient set-up.
This can be done in any number of ways, including with a CT scan, ultrasound, x-rays or GPS trackers. The use of IGRT allows us to deliver accurate radiation on a daily basis, minimizing the risk of set-up error. Otherwise, using IMRT to tightly conform the dose around targets without using IGRT could result in missing parts of the tumor.
Another advance in external beam radiation is Stereotactic RadioSurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). These techniques are designed to use one to five very high doses of radiation to treat smaller tumors. As with IMRT, there are many machines that are capable of delivering this type of treatment, and often these treatments are described by the treatment machine name, such as Cyberknife, Gamma Knife, Axesse, Synergy, Novalis, TomoTherapy, Trilogy and Truebeam.
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What form of radiation, if any, is appropriate for my cancer?
Unfortunately, there are many different types of cancer, and even different stages within a given cancer will have different optimal therapies. In addition, different people in different situations with different goals can also result in different treatment recommendations. The best solution is to discuss with your physicians who will consider your particular disease, stage of cancer, as well as your overall situation and desires in order to inform you of your treatment options and to help discuss what options work best for you and your particular situation.
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Advanced Oncology Center is equipped with the latest in innovative radiation therapy technology and is committed to ensuring the highest level of precision and accuracy in therapeutic modalities.
AOC is equipped with a Philips Brilliance CT Simulator specifically designed for improving the accuracy of radiation treatments.
Our linear accelerator is a newly upgraded state-of-the-art Elekta Synergy system, capable of Intensity Modulated Radiation Therapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) as well as Image-Guided Radiation Therapy (IGRT). For more information on how a linear accelerator works, please click here.
IMRT: Intensity Modulated Radiation Therapy allows us to conform high doses of radiation to tumor cells while sparing normal surrounding tissues. Additionally, with sophisticated treatment planning software, we are able to deliver different dose levels to different targets, allowing us to better optimize each patient's treatment to the risk and tolerance of each body area. This leads to improved radiation delivery to tumors, while significantly reducing side effects.
With the new Elekta Agility multi-leaf collimator (MLC) - the next generation in radiotherapy beam shaping technology - we are able to further improve and harness the shape of the radiation beams for small targets in stereotactic treatments with a high level of conformality.
VMAT: As the newest technology in advanced radiation therapy, our arc therapy system establishes new standards for radiation delivery in speed and precision for our patients. With VMAT, radiation beams sweep in uninterrupted arcs around the patient, dramatically decreasing treatment delivery times while increasing the conformality of our treatment plans. Our physicians can use VMAT to significantly reduce treatment times to as few as 10-12 minutes. By integrating 3D volume imaging technology into the treatment system, the physicians can visualize the tumor and targets in real-time with adjustments, making this technology the most accurate treatment delivery system in use today. For more information on Elekta VMAT technology, click here.
IGRT: Closer shaping of radiation delivery around cancer targets means that precision and accuracy of targeting are critical to success. Thus, we also offer cutting-edge Image-Guided Radiation Therapy (IGRT). This revolutionary innovation utilizes cone-beam computed tomography (CBCT) to ensure the high accuracy of daily treatments by mapping the set-ups in a 3-dimensional space, which is a significant improvement over the 2-dimensional image created by traditional port-films.
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