ABSTRACT
BACKGROUND: Radiation dose escalation within definitive radiochemotherapy (RTx/CTx) was not successful for stage III non-small cell lung cancer (NSCLC) using conventional fractionation (CF). Accelerated-hyperfractionation (AHF) counteracts tumour cell repopulation. In this observational study, the effects of neoadjuvant RTx/CTx using AHF or CF were studied by histopathology and using the survival end-point. METHODS: Data from all consecutive lung cancer patients treated with neoadjuvant RTx/CTx and thoracotomy between 08/2000 and 06/2012 were analysed. Patients received induction chemotherapy (cisplatin-doublets) followed by concurrent RTx/CTx using AHF (45 Gy/1.5 Gy bid) or CF-RTx (46 Gy/2 Gy qd). For estimating the AHF versus CF treatment effects, multivariate analysis (MA), propensity score weighting (PS), and instrumental variable analysis (IV) were used. FINDINGS: 239 patients were treated, median age 58 (34-78)years, stage II/IIIA/B: 19/88/132, squamous cell/adenocarcinomas/other: 98/107/34; AHF/CF-RTx 112/127 patients. No significant differences between both groups, in tumour related factors (age, gender, Charlson comorbiditiy score, lactate dehydrogenase (LDH), haemoglobin, stage, histopathology and grading), existed. Crude rates of pathologic complete responses (pCR) in AHF and CF groups were 37% and 24% respectively. The dose fractionation effect on pCR was significant (p ⩽ 0.006, PS and IV analyses). There was a significant dependence of pCR on biologically effective dose. pCR also depended on treatment time (MA, p = 0.04; PS, p = 0.0004). Median treatment time was 22 d or 31 d using AHF or CF (p<0.0001), respectively. Adenocarcinomas had lower pCR rates in comparison to other histologies. Five-year survival of patients with pCR was 65%, independent of the fractionation. INTERPRETATION: This large monoinstitutional analysis demonstrates an increased effect of AHF on pCR of lung cancer which modifies overall survival.
