PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s): Although the lung cancer often arises from peripheral zone of the organ and attaches to pleura on CT scans before treatment, some of the tumors are diagnosed with T1 diseases because the evaluation of pleural invasion with the use of CT scans is generally difficult. The aim of the study is to investigate the impact of pleural attachment on recurrence in stage I NSCLC patients receiving SBRT.
Materials/Methods: Among the patients receiving SBRT for primary lung cancers between 2007 and 2016, the inclusion criteria are as follows: (i) clinically T1N0M0 stage (UICC 7th edition), (ii) histologically proven NSCLC, (iii) for patients not fulfilling the (ii) criteria, the tumor has FDG activity on PET scans or consecutive growth on CT scans, and clinically diagnosed as malignant with the consensus of thoracic surgeons, medical oncologists and radiation oncologists. Patients with central tumors or with pure ground grass opacity on CT scans were excluded. In this study, if the primary tumor on CT scans was attached to visceral pleura 5mm long or more on lung window setting, the case was classified as patients with pleural attachment (A+). Other patients without (A+) were classified into (A-). The SBRT dose was basically 48-60Gy/4fractions. Local control (LC), progression-free survival (PFS) and overall survival (OS) were calculated using Kaplan-Meier method and the log-rank test was used to determine statistical significance for Kaplan-Meier curves. Cox proportional hazards regression analyses were done to identify factors associated with PFS and OS. Valuables with a p value of <0.10 were entered into a multivariable model. The p value of <0.05 was considered significant.
Results: Totally 154 consecutive patients were reviewed, including 112 males and 42 females, and 103/42/8/1 patients with PS 0/1/2/4. Median age was 79.5 (range 56-96) and 108/46 patients had T1a/T1b diseases. Pathological diagnosis was as follows: Ad 93/SCC 11/large cell 1/NSCLC 15/unknown 34. Thirty-three and 121 patients were classified into (A+) and without (A+) respectively. The median follow-up time for survivors was 44.5 months. Three-year LC, OS and PFS in entire cohort were 88.3/86.4/74.2% respectively. Three-year LC, OS and PFS in (A-) and in (A+) were 95.6/59.3% (p<0.001), 91.6/83.2% (p=0.029) and 83.4/39.1% (p<0.001) respectively. Among the valuables such as (A+) or (A-), tumor size, FDG uptake, with or without respiratory gated RT, operability, CRP, PS, pathology, the existence of IP, RT dose, age and sex, multivariate analyses have indicated (A+) was statistically significant for LC (p<0.001) and PFS (p<0.001). Tumor size (p=0.023) and the existence of IP (p=0.045) were also significant for PFS.
Conclusion: Pleural attachment on CT scan was a statistically significant prognostic factor for LC and PFS. Considering the lower tumor control rate in (A+), those patient cohorts might not be good candidates for SBRT.
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