Rectal cancer: VMAT, 3DCRT similarly effective for estimating SCR

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  • Based on the modeling used in this study, there was no statistically significant difference in second cancer risk (SCR) using volumetric modulated arc therapy (VMAT) or 3D conformal radiotherapy (3DCRT) in patients with rectal cancer.

Why this matters

  • SCR is a concern in long-term cancer survivors who undergo radiotherapy.

Key results

  • Organs adjacent to the planning target volume had highest mean excess lifetime attributable risk (LAR).
  • For 25 x 1.8 Gy, LAR for VMAT was 2.3%-3.0% and 2.0%-2.7% for 3DCRT.
  • For 5 × 5 Gy, LAR for VMAT was 1.4%-1.9% and 1.2%-1.6% for 3DCRT.
  • Organ-specific excess LAR was increased significantly for VMAT, especially bladder and colon.
  • Target volume size and shape affected SCR and was highest for patients ...