The Clinical Benefits of Proton Therapy
October 7, 2024
From the time the FDA approved proton therapy to treat patients in 1988, research through clinical trials has helped the field of radiation oncology better understand the benefits of this advanced treatment. Extensive studies over the years has informed us of the clinical benefits of proton therapy on tumors in general and how it offers favorable outcomes in the treatment of specific cancer types.
Learn more about the clinical benefits of proton therapy for the various disease sites we treat below. Click here to review the sources of the studies referenced on this page.
Clinical Benefits of Proton Therapy Compared to Conventional Radiation Treatments by Disease Site:
Anal Cancer
Anal Cancer
Proton therapy reduces dose to the bladder, bone marrow, and bowel, with similar disease outcomes to photon therapy. Longer follow-up time will clarify how this translates to less treatment related toxicity.
Base of Skull Cancer
Base of Skull Cancer
Proton therapy for skull-base chordoma and chondrosarcoma yields low rates of Grade 2 brainstem toxicity (1.3%) despite the high doses utilized (median total dose of 73.8 Gy). Proton therapy can allow for target volume coverage while maintaining point doses to the anterior brainstem to under 64 Gy.
Breast Cancer
Breast Cancer
Side effect and secondary lung and contralateral breast cancer rate odds following breast cancer treatment are significantly lower following proton beam therapy, compared to photon therapy (odds ratio 0.62). Proton therapy leads to large reductions in dose to almost all relevant normal (uninvolved) organs for bilateral breast cancer cases, and is similarly helpful for patients with previous radiation to the same breast or to the contralateral side.
Cental Nervous System
Central Nervous System
Proton therapy yields less dose to important brain substructures for adults with brain tumors, which is expected to result in a decrease in neurocognitive impairment in the aftermath of radiation, compared to photon therapy. Proton beam therapy results in excellent rates of long-term local control (94%) and low rates of significant side effects (2%) for intracranial meningioma.
Head and Neck
Head and Neck
The lessened side effects with proton beam therapy yields lower rates of feeding tube placement or reliance during or after radiation therapy, compared to photons. Additionally, there are fewer hospitalizations seen after proton therapy, and less cough and lack of taste. For head and neck reirradiation, proton therapy offers an avenue for disease control and improved outcomes compared to prior series of photon-treated patients.
Esophageal
Esophageal
Notable improvements in proton dosimetry (heart, lung, spinal cord dose) compared to even advanced photon techniques likely helps to drive these reduced rates of side effects seen with proton therapy patients. Proton therapy yields significantly lower cardiopulmonary toxicities with protons. Compared to proton patients, photon patients experienced 2.3x higher total toxicity (side effect) burden and 7.6x higher post-operative complication scores.
Gynecologic
Gynecologic
Whole pelvic proton therapy for gynecologic malignancies (endometrial, cervical, vaginal cancer) yields favorable locoregional control with low rates of significant genitourinary or gastrointestinal side effects. Long term quality of life outcomes approach the normal (untreated) age-matched population for patients with GYN cancers treated with proton beam therapy on the prospective APROVE-trial.
Liver
Liver
Proton beam yields low doses to uninvolved liver and therapy significantly improves progression free survival and local control (tumor control, 5.64x greater odds of control for protons) for hepatocellular carcinoma compared to transarterial chemoembolization (TACE). Proton therapy led to significantly less need for hospitalization, and a 28% cost savings relative to TACE.
Lung
Lung
Proton therapy yields reduced rates of severe lymphopenia and anemia (hematologic side effects) during lung cancer radiation, which is associated with better overall survival. Proton therapy giving less dose to the aorta and thoracic bone marrow (compared to photons) may be the driver behind this. Proton therapy is an avenue to re-irradiate radiorecurrent lung cancers with limited toxicity.
Lymphoma
Lymphoma
Treating mediastinal (anterior chest) masses with proton therapy using breath hold technique minimizes dose to normal organs more than any other technology available in the US. When modeling late effects from radiation such as heart failure, myocardial infarction, valvular heart disease, lung cancer, or breast cancer, one group found treating with protons instead of photons translates to significant improvements in theoretical “life years lost” due to potential side effects from the radiation dose received.
Pancreatic
Pancreatic
Proton beam therapy for locally advanced pancreatic cancer typically has dosimetric advantages (less dose to small bowel, liver, duodenum, stomach), is well tolerated, and comparable to photon based techniques in terms of effectiveness. Future studies may elucidate how the dosimetric advantages translate to clinical benefit (less side effects).
Pediatric
Pediatric
Pediatric brain tumor patients receiving proton beam therapy have superior neurocognitive outcomes, compared to patients who received photon therapy. The majority of proton beam patients who are treated for intracranial tumors demonstrate stability in baseline cognitive function over time. Proton beam therapy yields excellent tumor control with low toxicity rates and lower projected rates of secondary malignancies in adolescent and young adult patients.
Prostate
Prostate
Proton therapy for prostate cancer demonstrates minimal treatment-related toxicities and very good oncologic outcomes. Prostate patients in need of radiation to the pelvic lymph nodes seem to experience less gastrointestinal side effects during their radiation course compared to photon-based series, which is likely due to less dose to the small bowel.
Rectal
Rectal
Protons offer lower dose to small bowel, bone marrow, and bladder, which can be very helpful for certain rectal cancer cases for which sparing these structures as critical, such as concordant inflammatory bowel disease or prior radiation exposure (re-irradiation).
Sarcoma
Sarcoma
For soft tissue sarcoma, proton therapy has capacity to maintain appropriate target coverage, similar oncologic and wound healing outcomes, with reduction in doses to adjacent bone, soft tissue, and joints, compared to photon-based techniques which would help limit long term rates of fracture or joint/limb fibrosis. Proton therapy has improved disease control and toxicities for treatment of chest wall, spinal, or paraspinal Ewing sarcoma, compared to historical photon series.
Skin
Skin
Proton therapy yields less dry mouth, taste changes, and weight loss compared to photon therapy for treatment of skin cancers involving the parotid gland. For locally advanced skin cancers requiring ipsilateral radiation therapy, proton therapy yields lower rates of grade 2 taste changes, oral mucositis, and nausea. Additionally, an improved ability to spare critical structures (eyes, lenses, retinas, lacrimal glands, mouth) near tumor.
To discuss a case, contact our physician liaisons at [email protected] or call 410-469-1085 to be connected with a specialist for your patient’s specific disease site.