Photons, protons or carbon ions for stage I non-small cell lung cancer - Results of the multicentric ROCOCO in silico study

Radiother Oncol. 2018 Jul;128(1):139-146. doi: 10.1016/j.radonc.2018.02.024. Epub 2018 Mar 12.


Purpose: To compare dose to organs at risk (OARs) and dose-escalation possibility for 24 stage I non-small cell lung cancer (NSCLC) patients in a ROCOCO (Radiation Oncology Collaborative Comparison) trial.

Methods: For each patient, 3 photon plans [Intensity-modulated radiotherapy (IMRT), volumetric modulated arc therapy (VMAT) and CyberKnife], a double scattered proton (DSP) and an intensity-modulated carbon-ion (IMIT) therapy plan were created. Dose prescription was 60 Gy (equivalent) in 8 fractions.

Results: The mean dose and dose to 2% of the clinical target volume (CTV) were lower for protons and ions compared with IMRT (p < 0.01). Doses to the lungs, heart, and mediastinal structures were lowest with IMIT (p < 0.01), doses to the spinal cord were lowest with DSP (p < 0.01). VMAT and CyberKnife allowed for reduced doses to most OARs compared with IMRT. Dose escalation was possible for 8 patients. Generally, the mediastinum was the primary dose-limiting organ.

Conclusion: On average, the doses to the OARs were lowest using particles, with more homogenous CTV doses. Given the ability of VMAT and CyberKnife to limit doses to OARs compared with IMRT, the additional benefit of particles may only be clinically relevant in selected patients and thus should be carefully weighed for every individual patient.

Keywords: In silico planning study; Multicentric trial; Particle therapy; Radiotherapy; Stage I NSCLC.

Publication types

  • Multicenter Study

MeSH terms

  • Carbon / therapeutic use*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Carcinoma, Non-Small-Cell Lung / radiotherapy*
  • Dose-Response Relationship, Radiation
  • Heavy Ion Radiotherapy / methods*
  • Humans
  • Lung Neoplasms / pathology
  • Lung Neoplasms / radiotherapy*
  • Mediastinum / radiation effects
  • Organs at Risk / radiation effects
  • Photons / therapeutic use*
  • Proton Therapy / methods*
  • Radiosurgery / methods
  • Radiotherapy Dosage
  • Radiotherapy Planning, Computer-Assisted / methods
  • Radiotherapy, Intensity-Modulated / methods


  • Carbon