The nature of bone and soft tissue sarcomas makes them ideal candidates for treatment with proton therapy. Sarcomas tumors are often located near sensitive tissues and require high curative doses,so it is important to treat them with the most precise types of radiation available, such as proton therapy.1
Ocular cancer can be difficult to treat because of its proximity to vital organs and vulnerable tissue. Since protons are more easily controlled than conventional X-rays, they can deliver powerful radiation doses to the tumor site without causing unnecessary damage to surrounding tissue in the eye and head, reducing the risk of side effects. Ocular melanoma is the most common type of eye tumors1. Proton therapy allows eye and vision presavation by limiting damage to the cornea, lens, retina, fovea, or optic nerve2. Similarly, it is also a treatment of choice for ocular tumors near the optic nerve or macula3.
Reirradiation increases risks of short- and long-term radiation-related side effects1,2. Contrary to conventional X-ray therapy, protons have the ability to aim a higher dose of radiation directly inside the tumor and to spare surrounding healthy tissue, which means they can be used for reirradiation of almost any disease site. Patients with recurrent disease who had received prior radiotherapy are good candiates for proton therapy that targets tumors precisely while limiting radiation exposure to healthy tissues. Proton therapy may improve treatment outcomes in patients with recurrent tumors3.
There is substantial evidence as to the efficacy of proton therapy in radiation treatment for thoracic cancer. With the latest delivery technique, pencil beam scanning, equipped with motion mitigation and plan optimization, the maximum energy of protons is deposited in the tumor, for better conformality and greater sparing of surrounding structures than photon radiation1,2,3. This spares surrounding organs at risk such as the heart, esophagus, spinal cord, lung and brachial plexus from radiation dose so as to reduce risks of radiation-induced toxicities such as esophagitis, pneumonitis and cardiopulmonary impairment4,5.
In addition to decreasing toxicity, proton therapy can improve local control and survival by allowing the delivery of a higher dose6,7.
A randomized phase 3 study showed that proton therapy is comparable to advanced photon techniques such as IMRT in tumor control and survivals while decreasing adverse events. For paranasal sinus and nasal cavity malignancies, proton therapy could be associated with higher disease-free survivals and locoreginal tumor control compared to IMRT.1,2 Proton therapy also shows significantly lower rates of acute dysphagia, dysgeusia, mucositis and nausea, as well as of weight loss, opioid use, and gastrostomy tube dependence.3,4 For recurrent head and neck cancers requiring reirradiation, proton therapy maximizes the targeted dose of radiation to the tumor while minimizing damage to surrounding tissues, even in patients who have received multiple prior courses of radiotherapy5.
Prostate cancer is the second most frequent in men worldwide1, traditional radiation treatment carries the risk of serious toxicity due to the proximity of important nerves, the rectum and the bladder2. By targeting the tumor, proton therapy can decrease the risk of damage to surrounding organs. It lowers the risk of damaging healthy tissue and provides patients with better quality of life. Gynecological cancers such as cervical, endometrial, uterine, vaginal and vulvar cancer can also be good indications for proton therapy. As it allows for higher doses of radiation to be delivered to the tumor without damaging surrounding healthy tissue and organs, Proton therapy is an established and efficacious treatment for localized prostate cancer that achieves highly effective tumor control with excellent toxicity outcomes and patient quality of life comparable to advanced radiotherapy techniques. For selected patients such as patients with high-risk disease, node-positive disease or recurrent disease, proton therapy offers potential for reduction in short- and long-term side effects by minimizing radiation dose to healthy tissues.3 Protons may also help spare hormone function in younger women by preserving the ovaries.
Data shows that proton therapy has great potential to increase therapeutic tolerance for patients with gastrointestinal tumors. It allows for lower toxicity to surrounding healthy tissues, less long-term side effects1 and a More aggressive radiation dose to the tumor target2. The possibility of decreasing radiation dose to organs at risk may also facilitate the compliance and intensification of systemic therapy such as chemotherapy, targeted therapy and immunotherapy3.
The largest consensus on the advantage of proton over conventional radiotherapy is in the field of pediatric oncology. Given the 70-80%1 survival rate and long life expectancy2, finding forms of radiation therapy that have a positive impact on the quality of life of children undergoing cancer treatment has increasingly become a focal point among pediatric oncologists. Clinical outcome data shows that proton therapy have a positive impact on the quality of life of children undergoing cancer treatment3.
