Interfraction interval does not affect survival of patients with non-smallcell lung cancer treated with chemotherapy and/or hyperfractionated radiotherapy: A multivariate analysis of 1076 RTOG patients

Purpose: It was observed by Jeremic et al. that a shorter interfraction int erval (IFI) was associated with an improved survival in patients (pts) with locally advanced non-small cell lung cancer (NSCLC) treated with hyperfrac tionated radiation therapy (HFX-RT), with or without chemotherapy (CT), Our analysis was undertaken to verify this hypothesis. Methods and Materials: Records of patients treated on 5 Radiation Therapy O ncology Group (RTOG) studies were reviewed, and an actual IFI, defined as a mean of all daily IFIs, was calculated, RT dose was 1.2 Gy BID to 69.6 Gy, The relationship between the length of IFI and the median survival time an d incidence of esophagitis was investigated, Results: In 682 pts eligible for this analysis, a full dose of RT was deliv ered and at least 90% of all daily IFIs were available, The actual mean IFI was as follows: 4-4.9 h in 51% of pts; 5-5.9 h in 17%; 6-6.9 h in 28% and 7-8 h in 4%, In multivariate analysis, only lack of weight loss, use of CT, low nodal stage and good KPS, but not IFI (4-6 h vs, 6-8 h) were associate d with an improved survival for all pts (p values: < 0.0001; < 0.0001; 0.00 6; 0.006, and 0.73, respectively), as well as for HFX-RT only pts, For the CT-HFX-RT pts, not enough data points are available for a meaningful analys is, Length of IFI did not influence the incidence of Grade 3 or higher esop hagitis (p = 0.82), but use of CT was associated with a 12-fold greater ris k of developing severe esophagitis (p < 0.0001). Conclusion: Length of IFI (4-6 h vs, 6-8 h) did not influence survival and acute complications incidence in pts with NSCLC treated in RTOG studies wit h HFX-RT to 69.6 Gy, Previously identified factors, such as use of CT, mini mal weight loss, good KPS and low nodal stage, were confirmed again to be a ssociated with a favorable prognosis in a multivariate analysis, Use of CT was associated with a 12-fold greater risk of developing severe esophagitis than HFX-RT alone, It appears that an IFI of 4-8 hr is acceptable in clini cal practice for pts with NSCLC, treated with HFX-RT, (C) 1999 Elsevier Sci ence Inc.