This review article of radiotherapy in none other than the New England Journal of Medicine is the PR course correction we’ve been waiting for, providing historical context and explaining the contrasting sophistication of modern technology with minimal radiotherapy jargon. Radiotherapy remains the second most common cancer treatment after surgery, spanning curative and palliative intent. Conventional 1.8–2.0 Gy fractions were once a necessity of wide fields and limited imaging, delivered low and slow to protect generous swaths of normal tissue. Enter CT-based planning, IMRT/VMAT, image guidance, motion management, and now MRI- and PET-linacs enabling hypofractionation and ablative dosing to incredibly precise fields. Acute toxicities (e.g., mucositis, dermatitis, pneumonitis) largely reflect stem-cell depletion and inflammatory cascades. Late effects (e.g., fibrosis, vascular injury, organ dysfunction) emerge months to years later, driven by chronic inflammation, senescence, and architectural distortion. Risk tracks with dose, volume, fractionation, concurrent therapy, and host factors (e.g., genetics, comorbidities, etc). Modern conformal techniques have significantly reduced severe late toxicity rates, while genomic classifiers and adaptive planning hint at a future where dose is personalized to further exploit the therapeutic ratio of our healing rays. | Citrin & Timmerman, N Engl J Med 2026
