A review on proton therapy of cancer

Proton therapy has emerged as an advanced form of external beam radiotherapy that exploits the unique physical property of the Bragg peak to deliver high radiation doses to tumours while minimizing exit dose to surrounding normal tissues. This dosimetrist advantage is particularly relevant in paediatric cancers, central nervous system tumours, head and neck malignancies, and situations requiring re-irradiation, where reduction in late toxicities and preservation of organ function are critical. Clinical evidence demonstrates reduced acute and long-term complications, especially in children, though survival benefits over state-of-the-art photon techniques are less consistently established in adults. Modern intensity-modulated proton therapy (IMPT) enhances conformality but introduces uncertainties such as range variation and variable relative biological effectiveness, which necessitate robust treatment planning. While cost and limited accessibility remain barriers to widespread adoption, health-economic analyses suggest proton therapy may be cost-effective in select patient populations with long life expectancy or high risk of treatment-related morbidity. Emerging directions include adaptive strategies, biological optimization, and ultra-high dose-rate “FLASH” proton therapy, which show promise for further widening the therapeutic window. Overall, proton therapy represents a valuable and evolving modality in cancer management, with strongest justification in pediatric and anatomically complex tumors , and ongoing trials are expected to better define its role across common adult cancers.