Why choose proton therapy?
There are many advantages to choosing proton therapy. Completely noninvasive, no cut or incision is made to remove the cancer. This makes it an ideal treatment choice for inoperable tumors and pediatric tumors. The once-daily therapy sessions are also completely painless, and the patient can leave immediately following treatment.
Perhaps most importantly, proton therapy allows patients to live life to the fullest throughout treatment. Because of proton therapy’s accuracy, many of the side effects of radiation treatment can be significantly reduced. This means a much lower chance of side effects such as incontinence or impotence in prostate cancer patients. It also means a return to normal, daily life and activities.
What types of cancer are being treated?
Proton radiation therapy is used to treat any cancer or other disease affecting the:
- Other conditions
- Base of skull
- Brain and spinal cord
- Head and neck
- Chest and abdomen
LLUMC investigators are modifying the synchrotron and proton beam transport system to allow treatment of larger fields, such as those required to for treatment of breast cancer and Hodgkin's disease. We expect this technology to be available in the near future.
Why don't we hear more about the benefits of proton therapy?
Most patients and many doctors simply aren’t aware of proton therapy or of its documented benefits. There are only 36 proton therapy centers in the United States treating more than 17,000 patients a year, or less than one percent of patients diagnosed with cancer. Conversely, there are approximately 2,500 conventional radiation therapy centers (referred to as IMRT) in the U.S. with the treatment being used for approximately one million of the 1.5 million Americans diagnosed with cancer.
Why aren't there more proton therapy centers?
Opening a proton therapy center requires a tremendous commitment of resources – dollars, personnel and time – and most organizations simply don’t have the ability to enter this space. As an example, the cost of building a multi-room proton center is as much as 40 times that of a conventional IMRT center. That said, many renowned academic medical centers nationwide are seeing the proven benefits of proton therapy and are following our lead by building or operating their own proton treatment centers. It is important for a proton treatment center to be hospital-owned and hospital-based as that assures that patients will have access to all of the support services (nutritionists, physical therapists, etc.) they may need without having to go anywhere else.
How long does the proton radiation stay in my body?
Your body does not become radioactive and poses no risk of radiation exposure to others.
Is proton therapy still in the experimental stages?
Since LLUMC brought modern proton treatment for cancer into the mainstream in 1990, there have been countless studies and trials that have shown proton therapy to be the treatment of choice for many types of cancer. Far from experimental, proton treatment has been refined and, coupled with leading-edge technology, has become one of the best treatment options for doctors and patients. There are literally hundreds of peer review journal-published articles proving the benefits of proton therapy including: excellent effectiveness for both adults and children, it can be used on recurrent tumors (even on patients who already have received radiation), reduces risk of spillover radiation into healthy tissue and organs, and improves quality of life before and after treatment.
How does proton therapy's effectiveness compare to IMRT or other x-ray treatments?
Proton beams can be delivered in higher doses and with far more accuracy, proton therapy typically can control cancer with fewer treatments than IMRT. This pinpoint accuracy also results in fewer long-term side effects (since the radiation does not spill over and damage healthy tissue and organs) meaning that patients treated with proton therapy experience a higher post-treatment quality of life as compared to IMRT and even conventional x-ray treatments.
What's the discussion about proton therapy being part of a "medical arms" race to attract patients?
Our focus is how to best treat patients to preserve their quality of life. The “medical arms race” that is mentioned in the media concerns the growing number of proton therapy centers and their potential impact on the more than 2,500 IMRT radiation centers in the United States. If all of the proton therapy centers in the U.S. scheduled for completion over the next five years were working at full capacity, the number of patients treated wouldn’t exceed one percent of the total number of patients receiving IMRT.
How does the cost of proton therapy compare with other forms of radiation and surgery used to treat cancer?
The long-term cost of a patient treated with proton therapy is far less than that of a patient treated with surgery or IMRT. That is because proton therapy patients experience less side effects and a better quality of life, and that reduces ongoing medical and societal costs associated with that patient. As for costs of the treatment itself, reimbursement from private health insurers varies depending on the insurance carrier as well as the type of proton center that administers treatment. There are different reimbursement rates associated with non-profit, hospital-based, academic medical centers and free-standing centers. At some free-standing proton centers, the reimbursement for proton is at virtually at the same rate of reimbursement as IMRT. The Centers of Medicare and Medicaid Services only reimburses hospital-based, non-profit medical centers. Loma Linda University Medical Center is one of only three such centers in the United States.
Does insurance cover proton therapy?
Proton therapy is typically covered by Medicare. Other insurers will cover proton radiation therapy on a case-by-case basis. Our financial coordinators can assist you in working with your insurance company to obtain authorization.
How is proton radiation therapy planned and delivered?
The precision of the proton beam requires equal precision in planning and delivery. This is done in two steps:
- A three-dimensional reconstruction of the tumor obtained by performing computed tomography (CT) scans through the region of interest (chest, pelvis, etc.) with images taken at 2 to 3 millimeter intervals.
- A reproducible treatment position that minimizes movement errors
Once the immobilization device has been made and the CT scan has been performed, the treating physician traces the tumor and surrounding normal tissues on a computer. This tracing is done image by image to get the most precise map.
Next, physicists and dosimetrists create a treatment plan by outlining on the computer a series of proton beams entering at various angles. From these, they calculate the radiation dose being given to the tumor and normal tissues.
This plan is reviewed by the physician, and once approved, it is transferred electronically to a series of automated machines that make the special devices (apertures and tissue-compensating filters) required by the plan. Before the patient’s first treatment, all of these devices are calibrated by the physics support staff to ensure that the planning and manufacturing are correct.
Is proton radiation therapy ever combined?
Yes. Conformal proton therapy is often used in conjunction with X-ray therapy. This method boosts the dose to sites of gross disease and allows irradiation of a large tissue volume. Depending on the amount of cancer within a particular lymph node and type of cancer that is present, a patient may be at risk for harboring microscopic nests of cancer cells within the nodes. These nodes may lie at some distance from the primary tumor and may not be irradiated if conformal proton treatment alone is delivered to the tumor.
The objective of the treatment plan is to treat both the primary tumor and any areas where a microscopic tumor might hide; reducing the risk of complications and permits treatment of potentially involved lymph nodes. Microscopic cancer within these nodes might be missed if X-rays were not used.
What does "conformal" mean?
A "conformal" beam can be shaped, or "conformed,” in three dimensions. The physician can shape the beam to match the shape of a tumor. This helps deliver most of the radiation to the targeted volume while avoiding the surrounding healthy tissue. This unique capability sets proton radiation therapy apart from other forms of external-beam radiation therapy.
What happens in the treatment room during treatment?
Once the treatment position is verified by a physician, the treatment is given. After changing into a gown, the patient enters the treatment room. The patient either lies in the mould or sits in a chair and is fitted with the mask. With laser beams as guides, the patient is moved to a position that is usually within half a centimeter (less than a quarter of an inch) of the calculated optimal position. To make the position more precise, the radiation therapy technologist obtains several low-power diagnostic radiographs or digital images.
Usually, it is necessary to move the patient a few millimeters to make the daily position conform exactly to the prescribed treatment position. These measurements and movements are performed by radiation therapy technologists.
After any necessary movements have been made, the patient's specially-created treatment devices are loaded into the beam line. Next, the technologists and physician retire to a control room to begin treatment. The control room is located just outside of each treatment room. After the prescribed radiation dose has been delivered, the computer shuts off the proton beam. The technologists then re-enter the room, and the patient is assisted from the mould or mask and changes out of the gown.
What is proton radiation?
Protons, which are positively charged subatomic particles, deposit energy differently than x-ray beams do. Compared to an x-ray beam, a proton beam that is delivered with sufficient energy (or "modulated") has a low "entrance dose" (the dose in front of the tumor). A proton beam also has a high-dose "Bragg peak" region, which is designed to cover the entire tumor. There is no "exit dose" beyond the tumor involved in proton radiation therapy. X-ray beams, by contrast, may deposit most of their dose in tissues in front of the tumor.
What is the difference between photon and proton radiation?
Photon beams make up traditional x-rays, carry a low radiation charge, and have a much lower mass than proton beams. Much of the photon beams' energy is deposited in the healthy tissue surrounding a tumor due to their low charge and mass, causing side effects and unnecessary tissue damage.
In contrast, proton beams can be energized to specific speeds or velocities that determine how deeply and where the beams will deliver their radiation. As the proton radiation beams move through the body, they slow down as they interact with orbiting electrons. When the protons have slowed down sufficiently, they release a burst of energy. The physician designs the proton radiation treatment so this burst occurs at the precise site of the cancer, minimizing damage to healthy tissue and reducing side effects.
Why are there several proton therapy treatments?
Proton radiation therapy is commonly given five days a week for several weeks. Normal cells and cancer cells often respond differently to radiation. The normal cells are typically better able to recover from small doses. We give small doses over an extended time period to allow normal cells to recover while inflicting lethal damage on cancer cells.