ABSTRACT
Objective:To analyze the treatment efficacy, safety and dose parameters of optimized hippocampus-avoidance prophylactic cranial irradiation (HA-PCI) in limited-stage small cell lung cancer (LS-SCLC) and explore the corresponding dosimetric parameters under the condition of narrowing the hippocampus avoidance region as hippocampus region plus 2 mm in three dimensions.Methods:Clinical data of patients with LS-SCLC receiving HA-PCI (hippocampus avoidance region defined as hippocampus region plus 2 mm in three dimensions) in Cancer Hospital Chinese Academy of Medical Sciences from August 2014 to June 2020 were retrospectively analyzed. Dose parameters of HA-PCI and adverse events were analyzed using descriptive statistics analysis. Changes of neurocognitive function, such as mini-mental state examination (MMSE) and Hopkins verbal learning test-revised (HVLT-R) scores, were evaluated by analysis of variance and Kruskal-Wallis H test. Overall survival (OS), progression-free survival (PFS) and intracranial PFS (iPFS) were calculated using Kaplan-Meier method. The cumulative incidence of local-regional recurrence (LRR), extracranial distant metastases (EDM), and locoregional recurrence (LR) were investigated under competing risk analysis. Results:A total of 112 patients were included, the median follow-up time was 50 months (95% CI: 45.61-54.38). The median volume of hippocampus was 4.85 ml (range: 2.65-8.34 ml), with the average dose ≤9 Gy in 106 patients (94.6%), ≤8 Gy in 92 patients (82.1%). The median volume of hippocampus avoidance area was 15.00 ml (range: 8.61-28.06 ml), with the average dose ≤12 Gy in 109 patients (97.3%), ≤10 Gy in 101 patients (90.2%). The 2-year cumulative LRR, EDM, LR rates were 16.9%, 23.2% and 28.5%, respectively. The 5-year cumulative LRR, EDM, LR rates were 23.2%, 26.9% and 33.3%, respectively. The 2-year iPFS, PFS and OS rates were 66.1% (95% CI: 57.9%-75.4%), 53.6% (95% CI: 45.1%-63.7%) and 80.4% (95% CI: 73.3%-88.1%), respectively. The most common grade I-Ⅱ adverse events were nausea (33.9%) and dizziness (31.3%), and only 1 patient developed grade Ⅲ nausea and dizziness. MMSE ( n=57) and HVLT-R tests ( n=56) showed no significant decline. Conclusions:Optimized HA-PCI can achieve similar dose limitation with favorable efficacy and light toxicity. No significant decline is observed in short-term neurocognitive function in evaluable patients.
ABSTRACT
Thoracic radiotherapy is a major treatment and dose fractionation remains controversial in limited-stage small cell lung cancer. Twice-daily (BID) radiotherapy, as a standard protocol established in prospective studies, is often replaced by other treatment strategies in clinical practice due to the occurrence of side effects and inconvenience. In addition, in inoperable stage Ⅰ small cell lung cancer with negative lymph nodes, stereotactic ablative radiotherapy (SABR) provides a new option for some elderly patients who are expected to be unable to tolerate long-term radiotherapy. The appropriate dose fractionation scheme can both ensure the therapeutic effects and reduce toxic effects. This article reviews the research of limited-stage small cell lung cancer about dose fractionation.
ABSTRACT
Objective:Simultaneous integrated boost radiation technique in limited-stage small cell lung cancer is lack of evidence. This prospective study aims to evaluate whether the simultaneous integrated boost is as efficacious and safe as conventional fractionated radiotherapy.Methods:Patients diagnosed with treatment-naive and confirmed limited-stage SCLC were eligible. Participants were randomly assigned (1: 1) to receive simultaneous integrated boost radiotherapy (PGTV 60.2 Gy/2.15 Gy/28F, PTV 50.4 Gy/1.8 Gy/28F) or conventional fractionated radiotherapy (PTV 60 Gy/2 Gy/30F). The primary endpoint was 2-year progression-free survival, and the secondary endpoints were 2-year overall survival, 2-year local-regional recurrence-free survival and toxicity.Results:Between February 2017 and July 2019, 231 patients were enrolled. We analyzed 216 patients whose follow-up time was more than 2 years or who had died, among whom 106 patients in the conventional fractionated radiotherapy group and 110 patients in the simultaneous integrated boost radiotherapy group. The median follow-up time was 37 months (95% CI: 35.2-38.7). The 2-year progression-free survival rates were 45.2% vs. 38.2%( HR=1.22, 95% CI: 0.87-1.72, P=0.2). The 2-year overall survival rates were 73.5% vs. 60.9%( HR=1.35, 95% CI: 0.90-2.04, P=0.14). The 2-year local-regional recurrence-free survival rates were 68.7% vs. 69.9%( HR=0.98, 95% CI: 0.62-1.56, P=1.0). Multivariate analysis showed that early radiotherapy yielded better 2-year progression-free survival, overall survival and local-regional recurrence-free survival than delayed radiotherapy in two groups ( HR=1.69, 95% CI: 1.18-2.41, P=0.003; HR=1.72, 95% CI: 1.09-2.70, P=0.018; HR=1.66, 95% CI: 1.01-2.73, P=0.046). Tumor staging was an influencing factor of overall survival (stage Ⅲ vs. stage Ⅰ-Ⅱ, HR=3.64, 95% CI: 1.15-11.57, P=0.028). The most common grade 3-4 adverse events were myelosuppression (21.7% vs. 15.4%, P=0.83), radiation pneumonitis (4.7% vs. 2.7%, P=0.44) and radiation esophagitis (3.8% vs. 1.8%, P=0.51). Conclusions:Simultaneous integrated boost radiotherapy yields equivalent efficacy and toxicities to conventional fractionated radiotherapy for limited-stage small cell lung cancer. Early radiotherapy can enhance clinical prognosis.