The predictive value of FDG PET for therapy response has been proven for a range of treatments for non-small cell lung cancer (NSCLC), now including concomitant chemoradiotherapy, which requires careful patient selection due to associated morbidity, according to a study published July 17 in the Journal of Nuclear Medicine.
Edwin A. Usmanij, from the department of nuclear medicine at Radboud University Nijmegen Medical Centre in Nijmegen, The Netherlands, and colleagues followed patients with locally advanced NSCLC as they underwent comcomitant regiments of dual-drug chemotherapy and intensity modulated radiotherapy. FDG PET was performed on all patients multiple times and predictive parameters including total lesion glycolysis (TLG) were calculated.
“With recent developments in dose escalation in NSCLC, a further increase in toxicity is reported,” wrote Usmanij et al. “Therefore, a need arises to predict therapy response at an early phase on an individual-patient basis, possibly leading to improved tumor control, a reduction in side effects, and eventually avoidance of futile costs of ineffective treatment.”
F-18 FDG PET has been found to predict NSCLC response to radiotherapy, chemotherapy and neoadjuvant chemotherapy, but little literature was available prior to this study regarding concomitant chemotherapy. Researchers performed FDG PET scans on 28 patients with locally advanced NSCLC with hilar or mediastinal lymph node involvement. Imaging was carried out before treatment, following the second week of therapy and two more times after treatment had ended, at two weeks and three months following treatment.
Chemoradiotherapy consisted of a combination of intensity-modulated radiotherapy administering 10-MV photons for a total dose of 66 Gy in 33 fractions of 2 Gy and 5 fractions per week. Chemotherapy included two cycles of cisplatin (50 mg/m2 of body surface area) given on days 1 and 8 preliminarily and during the second cycle on days 22 and 29. Intravenous etoposide was also used (100 mg/m2 of body surface area) on days 1-3 of the first cycle and again 22-24 the second time around. Overall treatment was completed within 45 days.
Results showed a drop of TLG of 38 percent or more was matched with substantially longer periods of progression-free survival, with such a decrease leading to 80 percent vs. 36 percent survival at one year. The difference in TLG even after just two weeks was predictive of therapy response and TLG measurement prior to treatment had prognostic value in determining progression-free survival.
“The current study in locally advanced NSCLC patients treated with concomitant chemoradiotherapy indicates that early in treatment F-18 FDG PET can be used to predict outcome,” said the authors. “The effect of combined treatment does not preclude its predictive capabilities, because we found TLG was predictive of [progression-free survival]. Both pretreatment TLG and the degree of change in TLG may be useful tools for individualizing treatment in locally advanced NSCLC.”