Prof. John Armstrong

Prof. John Armstrong is one of Ireland's most distinguished radiation oncologists, holding senior clinical and academic appointments at St Luke's Radiation Oncology Network — Ireland's national specialist radiotherapy provider — and at Beaumont Hospital in Dublin. With more than 28 years of experience in the field, he has been instrumental in advancing the clinical application of high-precision radiotherapy technologies in Ireland and has established St Luke's as a centre of excellence for stereotactic and image-guided treatments.

St Luke's Radiation Oncology Network operates across multiple Dublin hospital sites, providing the full range of modern radiotherapy services to patients from across Ireland and delivering approximately half of all radiotherapy treatments in the country. Prof. Armstrong has been a key figure in the network's development, contributing to the implementation of IMRT (intensity-modulated radiation therapy), IGRT (image-guided radiotherapy), VMAT (volumetric-modulated arc therapy), and SBRT (stereotactic body radiotherapy/SABR) — the latter representing the most technologically advanced form of outpatient radiotherapy available in Ireland.

His primary clinical subspecialty is thoracic oncology — specifically SBRT for early-stage non-small cell lung cancer (NSCLC) in patients who are medically inoperable or who prefer non-surgical treatment. He has designed and led Irish clinical studies demonstrating the safety and efficacy of SBRT in this population, contributing to international evidence that has established SBRT as a standard alternative to surgery for medically inoperable stage I NSCLC.

In addition to lung cancer, Prof. Armstrong treats prostate cancer with IMRT and brachytherapy, breast cancer with post-operative and hypofractionated radiotherapy, and head and neck cancers requiring complex multi-field treatment planning. He works within St Luke's multidisciplinary oncology teams, ensuring radiotherapy is fully integrated into each patient's overall care plan.

Prof. Armstrong completed his undergraduate medical degree in Ireland and subsequently trained in radiation oncology at St Luke's Hospital, Dublin, and through overseas fellowships at leading radiotherapy centres in the United Kingdom and North America. He developed particular expertise in lung cancer radiotherapy, treatment planning, and the emerging technologies of IMRT and IGRT during his fellowship training.

He holds the Fellowship of the Royal College of Radiologists (FRCR) — the primary specialist qualification in clinical oncology and radiology in the UK and Ireland — and the Fellowship of the Faculty of Radiologists of the Royal College of Surgeons in Ireland (FFRRCSI), the equivalent Irish qualification. He has contributed to radiotherapy quality assurance frameworks and training programmes within Ireland and has been active in ESTRO's educational and clinical trial activities.

Prof. Armstrong's principal clinical expertise lies in stereotactic ablative body radiotherapy (SBRT/SABR) for early-stage lung cancer — a technique that delivers very high doses of radiation in a small number of precisely targeted fractions, ablating the tumour with minimal damage to surrounding lung tissue. He has performed more SBRT treatments for lung cancer than any other Irish radiation oncologist and has contributed to the national implementation of this technique.

For prostate cancer, he delivers IMRT and VMAT with daily image guidance (IGRT), and performs prostate brachytherapy — both low-dose-rate (LDR) seed implantation and high-dose-rate (HDR) temporary implants. For breast cancer, he uses hypofractionated IMRT, including simultaneous integrated boost techniques. For head and neck cancers, he designs complex multi-field treatment plans incorporating salivary gland and spinal cord dose constraints. Stereotactic radiosurgery and fractionated SBRT for brain metastases are also within his practice.

Prof. Armstrong has authored over 120 peer-reviewed publications in radiotherapy and oncology journals including the International Journal of Radiation Oncology Biology Physics (Red Journal), Radiotherapy and Oncology, and Lung Cancer. His research on SBRT for early-stage NSCLC has been presented at ESTRO, ASTRO, and ESMO annual congresses and has contributed to Irish and European evidence bases for this technique.

He has collaborated extensively with the Irish Cancer Registry to generate national population-based data on radiotherapy outcomes in lung and prostate cancer, contributing to health service planning. His clinical trial work includes participation in ESTRO-sponsored multi-centre studies on hypofractionation and stereotactic radiotherapy. He has contributed to national treatment guideline development through the Irish Institute of Clinical Oncology (IICO) and serves as a reviewer for leading radiotherapy journals.

St Luke's Radiation Oncology Network and Beaumont Hospital are experienced in treating patients from across Ireland and from abroad who require specialist radiotherapy services, particularly for technically complex cases requiring SBRT or advanced IMRT techniques. Prof. Armstrong consults exclusively in English.

For international patients considering radiotherapy in Dublin, video consultations are available to review imaging (CT, PET-CT, MRI), pathology, and prior treatment history before a treatment plan is developed. EU/EEA patients can access care under the EHIC scheme and European cross-border healthcare directives. Dublin Airport offers direct connections to airports across Europe, making Dublin accessible for patients requiring a short course of outpatient SBRT — typically delivered in three to five fractions over one to two weeks.

Prof. Armstrong is a Distinguished Fellow of the Irish Institute of Clinical Oncology (IICO), recognised for his leadership in advancing radiotherapy standards in Ireland. He holds Fellowship of the Royal College of Radiologists (FRCR) and Fellowship of the Faculty of Radiologists of the RCSI (FFRRCSI) — the two most prestigious professional qualifications in radiation oncology for Irish practitioners. He received the Irish Cancer Society Research Award for his work on SBRT outcomes and his collaboration with the Irish Cancer Registry. He is an active member of ESTRO — the European Society for Radiotherapy and Oncology — and has contributed to ESTRO's scientific programme committee.