Education
BS – University of Michigan, Ann Arbor, Michigan
DO – Chicago College of Osteopathic Medicine, Chicago, Illinois
PhD – University of Utrecht, The Netherlands
Research Interests
I am currently Chair of Radiation Oncology at St. Jude Children’s Research Hospital in Memphis, Tennessee where I have practiced since 1996. Prior to my appointment at St. Jude, I was an attending physician in the Department of Radiation Oncology at the Memorial Sloan-Kettering Cancer Center in New York, New York. I was originally trained as a nuclear engineer at the University of Michigan. After completing my engineering degree, and prior to attending medical school at the Chicago College of Osteopathic Medicine, I worked in the area of radiation protection and safety for the French Atomic Energy Commission in Fontenay-aux-Roses, France. After medical school, I was a Fulbright Scholar to the Netherlands at the University of Utrecht where I received my Ph.D., cum laude, in experimental pathology. I interned at the Chicago Osteopathic Hospital and performed my residency at the Memorial Sloan-Kettering Cancer Center. As a part of my formal medical and residency training, I spent time at the Massachusetts Eye and Ear Infirmary in Boston and Curie Institute in Paris. In the latter part of my residency training, I was awarded a fellowship and spent time at the Joint Center for Radiation Therapy and Children’s Hospital Boston.
The subject of my research has been the application of advanced radiotherapy methods in the treatment of children with cancer. My focus has been in pediatric neuro-oncology where I have designed new treatments for children with brain tumors and modeled radiation-related CNS effects. The broad long-term goal of my research has been to increase the cure rates for the most common brain tumors and reduce or eliminate the side effects of radiation therapy. My work in the area of conformal radiation therapy for pediatric CNS tumors has provided the basis for the dose, volume and normal tissue tolerance guidelines used in most of the national cooperative group brain tumor trials for children with medulloblastoma, ependymoma, low-grade glioma and craniopharyngioma. My work has recently been highlighted in a number of oncology journals including Lancet Oncology, Journal of Clinical Oncology, and the International Journal of Radiation Oncology, Biology and Physics.
In the Children’s Oncology Group, I served as the Chair of the Radiation Oncology Discipline and Vice-chair of the CNS Disease Committee from 2006-2016. I was the Principal Investigator for the most recent national ependymoma study. My current efforts include leading the development of new guidelines to implement and research the role of intensity-modulated radiation therapy and proton beam therapy in the treatment of children with all types of brain and solid tumors. To that end, I completed a sabbatical at the Paul Scherrer Institute in Villigen, Switzerland, where I studied proton spot scanning. My goal is to lead the effort to develop institutional and collaborative protocols for St. Jude patients to receive proton beam therapy at established protons centers.
Diseases
- Ependymoma
- Craniopharyngioma
- Medulloblastoma
- Low-grade glioma
- Retinoblastoma
Special Interests
- Brain tumors in young children
- Side effects of radiation therapy
- Re-irradiation
- Proton therapy
Selected Publications
Craniopharyngioma
Merchant TE, Hoehn ME, Khan RB, Sabin ND, Klimo P, Boop FA, Wu S, Li Y, Burghen EA, Jurbergs N, Sandler ES, Aldana PR, Indelicato DJ, Conklin HM. Proton therapy and limited surgery for paediatric and adolescent patients with craniopharyngioma (RT2CR): a single-arm, phase 2 study. Lancet Oncol. 2023. doi:10.1016/S1470-2045(23)00146-8. PMID: 37084748; PMCID: PMC10408380.
Merchant TE, Dangda S, Hoehn ME, Wu S, Li Y, Wang F, Pan H, Boop FA, Jurbergs N, Conklin HM. Pediatric Craniopharyngioma: The Effect of Visual Deficits and Hormone Deficiencies on Long-Term Cognitive Outcomes After Conformal Photon Radiation Therapy. Int J Radiat Oncol Biol Phys. 2023. doi:10.1016/j.ijrobp.2022.09.061. PMID: 36130625.
Edmonston DY, Wu S, Li Y, Khan RB, Boop FA, Merchant TE. Limited surgery and conformal photon radiation therapy for pediatric craniopharyngioma: long-term results from the RT1 protocol. Neuro Oncol. 2022. doi:10.1093/neuonc/noac124. PMID: 35556133; PMCID: PMC9713513.
Merchant TE, Edmonston DY, Wu S, Li Y, Boop FA, Lustig RH. Endocrine outcomes after limited surgery and conformal photon radiation therapy for pediatric craniopharyngioma: Long-term results from the RT1 protocol. Neuro Oncol. 2022. doi:10.1093/neuonc/noac115. PMID: 35481829; PMCID: PMC9713512.
Müller HL, Tauber M, Lawson EA, Özyurt J, Bison B, Martinez-Barbera JP, Puget S, Merchant TE, van Santen HM. Hypothalamic syndrome. Nat Rev Dis Primers. 2022. doi:10.1038/s41572-022-00351-z. PMID: 35449162.
Low-grade Glioma
Bansal I, Merchant TE. Radiotherapy for pediatric low-grade glioma. Childs Nerv Syst. 2024. doi:10.1007/s00381-024-06460-2. Epub ahead of print. PMID: 38775957.
Acharya S, Wu S, Ashford JM, Tinkle CL, Lucas JT, Qaddoumi I, Gajjar A, Krasin MJ, Conklin HM, Merchant TE. Association between hippocampal dose and memory in survivors of childhood or adolescent low-grade glioma: a 10-year neurocognitive longitudinal study. Neuro Oncol. 2019. doi:10.1093/neuonc/noz068. PMID: 30977510; PMCID: PMC7594551.
Cherlow JM, Shaw DWW, Margraf LR, Bowers DC, Huang J, Fouladi M, Onar-Thomas A, Zhou T, Pollack IF, Gajjar A, Kessel SK, Cullen PL, McMullen K, Wellons JC, Merchant TE. Conformal Radiation Therapy for Pediatric Patients with Low-Grade Glioma: Results from the Children's Oncology Group Phase 2 Study ACNS0221. Int J Radiat Oncol Biol Phys. 2019. doi:10.1016/j.ijrobp.2018.11.004. PMID: 30419305; PMCID: PMC6548322.
Merchant TE, Kun LE, Wu S, Xiong X, Sanford RA, Boop FA. Phase II trial of conformal radiation therapy for pediatric low-grade glioma. J Clin Oncol. 2009. doi:10.1200/JCO.2008.20.9494. PMID: 19581536; PMCID: PMC3525947.
Merchant TE, Conklin HM, Wu S, Lustig RH, Xiong X. Late effects of conformal radiation therapy for pediatric patients with low-grade glioma: prospective evaluation of cognitive, endocrine, and hearing deficits. J Clin Oncol. 2009. doi:10.1200/JCO.2008.21.2738. PMID: 19581535; PMCID: PMC2799064.
Medulloblastoma
Merchant TE, Wu S, Onar-Thomas A, Gajjar A, Delaney A. Hypogonadism After Treatment for Medulloblastoma: Results From the SJMB03 Trial of Risk-Adapted Radiation Therapy. Int J Radiat Oncol Biol Phys. 2023. doi:10.1016/j.ijrobp.2023.01.001. PMID: 36641041.
Merchant TE, Wu S, Onar-Thomas A, Delaney A, Gajjar A. Endocrinopathy After Treatment for Medulloblastoma: Results From the SJMB03 Trial of Risk-Adapted Radiation Therapy. Int J Radiat Oncol Biol Phys. 2023. doi:10.1016/j.ijrobp.2022.12.016. PMID: 36563909.
Harreld JH, Zou P, Sabin ND, Edwards A, Han Y, Li Y, Bieri O, Khan RB, Gajjar A, Robinson G, Merchant TE. Pretreatment Normal WM Magnetization Transfer Ratio Predicts Risk of Radiation Necrosis in Patients with Medulloblastoma. AJNR Am J Neuroradiol. 2022. doi:10.3174/ajnr.A7393. PMID: 35058296; PMCID: PMC8985672.
Lucas JT, Tinkle CL, Huang J, Onar-Thomas A, Srinivasan S, Tumlin P, Becksfort JB, Klimo P, Boop FA, Robinson GW, Orr BA, Harreld JH, Krasin MJ, Northcott PA, Ellison DW, Gajjar A, Merchant TE. Revised clinical and molecular risk strata define the incidence and pattern of failure in medulloblastoma following risk-adapted radiotherapy and dose-intensive chemotherapy: results from a phase III multi-institutional study. Neuro Oncol. 2022. doi:10.1093/neuonc/noab284. PMID: 34894262; PMCID: PMC9248404.
Acharya S, Guo Y, Patni T, Li Y, Wang C, Gargone M, Ashford JM, Wilson L, Faught A, Reddick WE, Patay Z, Gajjar A, Conklin HM, Merchant TE. Association Between Brain Substructure Dose and Cognitive Outcomes in Children With Medulloblastoma Treated on SJMB03: A Step Toward Substructure-Informed Planning. J Clin Oncol. 2022. doi:10.1200/JCO.21.01480. PMID: 34714708; PMCID:PMC8683226.
Ependymoma
Mule' TN, Hodges J, Wu S, Li Y, Ashford JM, Merchant TE, Conklin HM. Social determinants of cognitive outcomes in survivors of pediatric brain tumors treated with conformal radiation therapy. Neuro Oncol. 2023. doi:10.1093/neuonc/noad080. PMID:37099477; PMCID:PMC10547513.
Howe GN, Edmonston DY, Dirks GC, Boop FA, Merchant TE. Conformal Radiation Therapy for Ependymoma at Age ≤3 Years: A 25-Year Experience. Int J Radiat Oncol Biol Phys. 2023. doi:10.1016/j.ijrobp.2023.01.016. PMID:36690160; PMCID:PMC10782549.
van Iersel L, van Santen HM, Potter B, Li Z, Conklin HM, Zhang H, Chemaitilly W, Merchant TE. Clinical impact of hypothalamic-pituitary disorders after conformal radiation therapy for pediatric low-grade glioma or ependymoma. Pediatr Blood Cancer. 2020. doi:10.1002/pbc.28723. PMID:33037871.
Merchant TE, Bendel AE, Sabin ND, Burger PC, Shaw DW, Chang E, Wu S, Zhou T, Eisenstat DD, Foreman NK, Fuller CE, Anderson ET, Hukin J, Lau CC, Pollack IF, Laningham FH, Lustig RH, Armstrong FD, Handler MH, Williams-Hughes C, Kessel S, Kocak M, Ellison DW, Ramaswamy V. Conformal Radiation Therapy for Pediatric Ependymoma, Chemotherapy for Incompletely Resected Ependymoma, and Observation for Completely Resected, Supratentorial Ependymoma. J Clin Oncol. 2019. doi:10.1200/JCO.18.01765. PMID:30811284;vPMCID:PMC7186586.
Merchant TE, Li C, Xiong X, Kun LE, Boop FA, Sanford RA. Conformal radiotherapy after surgery for paediatric ependymoma: a prospective study. Lancet Oncol. 2009. doi:10.1016/s1470-2045(08)70342-5. PMID:19274783; PMCID:PMC3615425.
Last update: October 2024