Hypo- vs. standard fractionated radiotherapy in inoperable NSCLC not candidate for chemo-radiation
PD-0668
Abstract
Hypo- vs. standard fractionated radiotherapy in inoperable NSCLC not candidate for chemo-radiation
Authors: Olfred Hansen1,2,3, Tine Schytte1, Lotte Holm Land1, Tine Bjørn Nielsen4, Morten Nielsen4
1Odense University Hospital, Oncology, Odense, Denmark; 2University of Southern Denmark, Institute of Clinical Research, Odense, Denmark; 3Odense University Hospital, Academy of Geriatric Research, Odense , Denmark; 4Odense University Hospital, Laboratory of Radiophysics, Odense, Denmark
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Purpose or Objective
The standard of radiation therapy (RT) for patients with inoperable
NSCLC not candidate for SBRT or chemo-radiation is fractionated RT without
chemotherapy. An alternative may be hypofractionated RT. In a
retrospective study, survival after hypo-fractionated RT regimen of 45 Gy/10
fractions (F) in 2.5 weeks was compared to a standard regimen of 66 Gy/30F in 6
weeks for patients treated 2014-2020
Material and Methods
Included were 45 patients with 45Gy/10F and 113 with 66Gy/30F in
performance status (PS) 0-3 with unilateral or mediastinal tumors, no distant
metastases at the time of radiation. Data on date of treatment, radiation dose
and fractionation, site, and the gross tumor volume (GTV), age, gender, date of
diagnosis, histology, tumor stage, white blood count (WBC) at time of
radiation, performance status, a modified Charlson comorbidity index (CCI),
body mass index (BMI), time span since diagnosis, and the date of death was
recorded. Multivariable Cox proportional hazard analyses (COX) were performed
for overall survival (OS) including factors with p <0.20 in univariate
analyses.
Some factors were dichotomized in
the analyses: PS <2/≥2, Age </≥70 year, WBC </≥12 mmol/L, BMI
</≥18.5 kg/m2, CCI <4/≥4. The volume of GTV was included logarithmically.
All patients were treated with VMAT. For 45Gy/10F no clinical target volume was
defined. Cutoff date was October 1st 2021 at which time the vital
status was known for all patients.
Results
The median and minimal potential
follow-up was 48.2 and 9.5 months for 45Gy/10F and 47.1 and 9.1 for 66Gy/30F.
The median, 2, and 4 year OS was 24.0 months, 51%, and 31% for 45 Gy/10F, and 17.7
months, 36%, and 25% for 66 Gy/30F.
Excluded from multivariable analyses
due to p >0.2 in univariate analyses were gender, histology, and N-stage. PS
and Age were significant factors p <.02 and both were correlated with
radiation dose. The analyses were therefore stratified PS <2/≥2 and age<70/≥70.
In COX, time span since diagnosis, smoking habit, WBC, and BMI were insignificant
factors with p>.10. The final model included log GTV (p=.003), CCI ≥4 (p=.034,
HR=1.6). Radiation dose was not significant (p=.56) 
Conclusion
There was no significant difference
in overall survival for hypofractionated RT 45Gy/10F and standard fractionated
RT 66 Gy/30F for inoperable patients with NSCLC not candidate for SBRT or
concurrent chemo-radiation.