What is Proton Therapy ?
In Although proton therapy is said to be a better targeted form of treatment, there is some disagreement on whether it provides an overall advantage compared to other much cheaper therapies. The National Health Service1 in the UK says that proton therapy is better with some rare cancers where the tumors are located at the base of the skull or spine. With traditional radiation therapy, such tumors cannot be targeted because of the risk of damage to vital surrounding tissue (nerves).
The MD Anderson Center at the University of Texas describes proton therapy as a 196-ton, cancer-killing machine with sub-millimeter precision that can target a patient's tumor "while sparing nearby healthy tissues and minimizing side effects. In its most simple terms, that's proton therapy."
The difference between proton therapy and standard radiation therapy
Standard radiation therapy
the X-ray beams deposit energy along their path before hitting their target (e.g. on the body's surface) and also beyond. The X-ray beam continues beyond the tumor, releasing energy and harming tissue - this is called the "exit dose".
In other words, the targeted cancer cells get hit, but so too do those along the X-ray beam before and past the tumor. This can lead to health problems after treatment.
the doctor can decide exactly when and where the proton releases most of its energy. This point is called the "Bragg peak".
The health care professional can determine the exact location of the Bragg peak, thus inflicting maximum damage to cancer cells and minimum harm to nearby tissue.
with standard radiation therapy, a lower-than-desired dose has to be used to minimize the damage to healthy cells.
With proton therapy, on the other hand, the doctor can use much higher radiation doses while at the same time protecting surrounding tissue and vital organs.
Proton therapy adapted to tumor shape
Tumors come in all shapes, sizes and locations, and they are unique for each patient. With patient-specific hardware, the radiologist can sculpt the proton beam, customizing it to strike within the borders of the tumor, whatever its shape might be.
The tumor can be hit with proton beams from different directions, further ensuring that damage to surrounding cells is kept to a minimum, thus reducing the risk of complications usually associated with radiation therapy.
Applications of proton therapy
Proton therapy treatments can be divided into two broad categories:
> Where higher dosages are needed
proton therapy is used for tumors that require the delivery of higher radiation doses, known as dose escalation.
Dose escalation has, in some cases, been demonstrated to provide better outcomes for patients than conventional radiotherapy. Examples include unresectable sarcomas, uveal melanoma (ocular tumors, tumors in the eye), and paraspinal tumors (chondrosarcoma and chordoma, alongside the spinal column).
> To reduce unwanted side effects
here the focus is not on a better chance of a cure but to minimize the undesirable side effects by limiting the damage to normal, healthy tissue. The radiation dose is the same as in conventional therapy. Examples include pediatric neooplasms and prostate cancer.