Incremental clinical value of a dedicated RT planning FDG PET-CT over staging PET-CT in non-small cell lung cancer

  • Dr Peter Lin, Liverpool Hospital, Australia
  • Dr Shalini Vinod, Department of Radiation Oncology, Liverpool Hospital, Australia
  • Dr Michael Lin, Department of Nuclear Medicine and PET, Liverpool Hospital, Australia
  • Dr Ivan Ho Shon, Department of Nuclear Medicine and PET, Liverpool Hospital, Australia
  • Dr Seu Som, Australia

    • Objectives: To evaluate whether FDG-PET performed for radiotherapy planning can detect disease progression, compared with staging PET.

    Methods: Thirteen patients underwent a planning PET-CT for curative RT (“RT-PET”) within eight weeks of a staging PET-CT for newly diagnosed NSCLC between 10/2007 and 1/2009. All studies were acquired on a Philips GXL PET-CT using the same protocols, except RT-PET is acquired on a RT flat bed. The images were interpreted by consensus readings of two physicians: location/number, visual grading (0-4: 3> liver, 4 >brain), max transverse diameter (“Max D”) (tumour margin is delineated by a SUV threshhold of 2.5) and max SUV of each lesion.Progressive disease (PD) is defined as >10% increase in max D.

    Results: RT-PET detected PD (primary or nodal) or new metastases in 8 pts (61%) (mean interval:30.2±14 days, range:7-54 days). For primary tumour, RT-PET detected PD in 5 pts (range: 12-32% increase in max D and 12-39% increase in SUV) and RT-CT detected PD in 3 pts (11-21% increase in max D, paired t test: p = 0.19). Stage-PET detected 28 mediastinal/hilar nodal sites. RT-PET detected PD in 11 of these lesions in 4 pts (31%) and CT detected similar progression in 8 lesions in 2 pts. RT-PET detected 10 new lesions in 3 pts (23%) resulting in upstaging to N3 in 2 pts (supraclavicular and hilar nodes) and M1 in 1 pt (bone).

    Conclusion: A dedicated RT PET-CT has the potential to detect disease progression and impact on RT planning in a large number of patients.