Proton Therapy May Decrease the Risk of These 5 Late Side Effects in Pediatric Cancer Survivors
 In General

Recent research suggests proton therapy may spare pediatric patients from common complications associated with photon-based radiotherapy.

Over the last 40 years, the 5-year survival rate for children diagnosed with cancer has skyrocketed from 10% to nearly 90%. Yet, approximately 60% of childhood survivors suffer from late side effects, such as growth deficiencies and secondary cancers.[1]

Late effects are serious — and sometimes life-threatening — chronic health complications appearing months or years after treatment for cancer. Pediatric patients are particularly vulnerable to late side effects because of their long natural life expectancy and the radiosensitive nature of developing tissue.

But proton therapy has given pediatric oncologists a promising option in the complicated matter of treatment planning for child patients. Because it offers a lower entrance dose and no exit dose, proton therapy may reduce the risk of damage to adjacent, normal tissue and the resulting side effects compared to photon-based radiotherapy.[2]

Late side effects proton therapy may prevent in pediatric cancer survivors

A growing body of research suggests that proton therapy may spare pediatric patients from developmental, cognitive, and other complications associated with photon-based forms of external beam radiotherapy. Here are 5 chronic late side effects that evidence suggests child cancer survivors may survive following proton therapy.

  1. Secondary malignancies

Research shows a strong correlation between radiation therapy and secondary cancers, including basal cell carcinoma[3],  breast cancer[4], and thyroid cancer[5], to name a few. On the other hand, an increasing number of studies suggest there is a decreased risk of secondary malignancies in childhood cancer survivors when treated with proton therapy instead of photon-based forms of radiotherapy. This includes, but is not limited to, pediatric patients treated for the following forms of cancer:

  • Cancers of the thoracic and abdominal regions[6]
  • Optic glioma and vertebral body Ewing’s sarcoma[7]
  • Medulloblastoma[8]
  • Retinoblastoma[9]

  1. Neurocognitive dysfunction

Proton therapy may spare pediatric patients from some of the neurocognitive effects of traditional irradiation. Studies by Kahalley et al.[10] and Merchant et al.[11] found higher intelligence quotient (IQ) scores in childhood brain tumor survivors treated with proton therapy.

  1. Hearing loss

Fortin et al. found hearing loss probability to be systematically less for pediatric brain tumor patients treated with protons over photon radiation therapy.[12]

  1. Endocrine dysfunction

A study of pediatric medulloblastoma patients found that patients receiving proton therapy had a reduced risk for hypothyroidism, sex hormone deficiency, a requirement for endocrine replacement therapy, and a greater height standard deviation score compared to those receiving photon radiation.[13]

  1. Cardiac mortality

Zhang et al. found decreased lifetime attributable risks of cardiac mortality when treated with proton craniospinal irradiation over photon CSI in a study of 17 pediatric medulloblastoma patients.[14]

To learn more about the use of proton therapy in the treatment of pediatric cancer, download our free white paper.

pediatrics and proton therapy

References

[1] National Cancer Institute. Surveillance, Epidemiology, and End Results Program. https://seer.cancer.gov/

[2] H. Paganetti, B.S. Athar, M. Moteabbed, et al. Assessment of radiation-induced second cancer risks in proton therapy and IMRT for organs inside the primary radiation field. Phys Med Biol 57: 6047–61 (2012) doi: 10.1088/0031-9155/57/19/6047

[3] T.C. Watt, P.D. Inskip, K. Stratton, et. al. Radiation-related risk of basal cell carcinoma: a report from the Childhood Cancer Survivor Study. J Natl Cancer Inst. 104(16):1240-50 (2012). doi: 10.1093/jnci/djs298

[4] C.S. Moskowitz, J.F. Chou, S.L. Wolden, et. al. Breast cancer after chest radiation therapy for childhood cancer. J Clin Oncol.20;32(21):2217-23 (2014). doi: 10.1200/JCO.2013.54.4601

[5] H. Lene, S. Veiga, E. Holmberg, et. al. Thyroid Cancer after Childhood Exposure to External Radiation: An Updated Pooled Analysis of 12 Studies. Radiation Research 185(5):473-484 (2016). doi: 10.1667/RR14213.1

[6] M. Tamura, H. Sakurai, M. Mizumoto, et. al. Lifetime attributable risk of radiation-induced secondary cancer from proton beam therapy compared with that of intensity-modulated X-ray therapy in randomly sampled pediatric cancer patients. J Radiat Res. 58 (3): 363-371 (2017). doi: 10.1093/jrr/rrw088

[7] H. Paganetti, B.S. Athar, M. Moteabbed, et al. Assessment of radiation-induced second cancer risks in proton therapy and IMRT for organs inside the primary radiation field. Phys Med Biol 57: 6047–61 (2012) doi: 10.1088/0031-9155/57/19/6047

[8] C.H. Stokkevag, G.M. Engeseth, K.S. Ytre-Hauge, et al. Estimated risk of radiation-induced cancer following paediatric cranio- spinal irradiation with electron, photon and proton therapy. Acta Oncol 53:1048–57 (2014). doi: 10.3109/0284186X.2014.92842

[9] V. Roshan, B.S. Sethi, A. Helen, et. al Second nonocular tumors among survivors of retinoblastoma treated with contemporary photon and proton radiotherapy. Cancer. 120(1):126-33 (2014). doi: 10.1002/cncr.28387

[10] L.S. Kahalley, M. Douglas Ris, D.R. Grosshans, et al. Comparing Intelligence Quotient Change After Treatment With Proton Versus Photon Radiation Therapy for Pediatric Brain Tumors. J Clin Oncol 34:1043-1049 (2016). doi: 10.1200/JCO.2015.62.1383

[11] T.E. Merchant, C. Hua, H. Shukla, et. al. Proton versus photon radiotherapy for common pediatric brain tumors: comparison of models of dose characteristics and their relationship to cognitive function. Pediatr Blood Cancer. 51(1):110-7 (2008). doi: 10.1002/pbc.21530

[12] D. Fortin, A. Ng, D.S.C. Tsang, et al. Predicting IQ and the Risk of Hearing Loss Following Proton Versus Photon Radiation Therapy for Pediatric Brain Tumor Patients. Int J Radiat Oncol Biol Phys 96(2):E684 – E685 (2016) doi: 10.1016/j.ijrobp.2016.06.2341

[13] B.R. Eaton, N. Esiashvili, S. Kim, et. al. Endocrine outcomes with proton and photon radiotherapy for standard risk medulloblastoma. Neuro Oncol. 18(6):881-7 (2016). doi: 10.1093/neuonc/nov302.

[14] R. Zhang, R.M. Howell, P, J. Taddei, et. al. A comparative study on the risks of radiogenic second cancers and cardiac mortality in a set of pediatric medulloblastoma patients treated with photon or proton craniospinal irradiation. Radiother Oncol. 113(1):84-8 (2014). doi: 10.1016/j.radonc.2014.07.003.