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T. Takanaka
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MS 24 - Management of GGO-Containing Nodule (ID 546)
- Event: WCLC 2017
- Type: Mini Symposium
- Track: Radiology/Staging/Screening
- Presentations: 1
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MS 24.04 - Possibility of Radiotherapy for GGO-Containing Tumors (ID 7757)
15:50 - 16:10 | Author(s): T. Takanaka
- Abstract
- Presentation
Abstract:
Purpose/Objective(s): The popularization of computed tomography (CT) in clinical practice have increased a frequency of discovering ground-glass opacity (GGO)-containing tumor in lung. Surgery has been regarded as the general treatment including a purpose of histological examination for such tumors and its prognosis is better than that of solid-type tumors. Stereotactic body radiation therapy (SBRT) is a rapidly prevailing treatment modality in the radical treatment of mainly inoperable or high risk operable cases with stage I non-small cell lung cancer (NSCLC), but the most tumors treated with SBRT were solid type because SBRT has been performed principally for the pathology-proven tumors and it is generally difficult to acquire histological specimen in the tumors composed of GGO. Therefore a prognosis of the stage I NSCLC cases treated with SBRT when their tumors contained GGO has not been clear. The purpose of this presentation is to review the treatment outcomes for SBRT for the patients with GGO-containing tumor in our multi-institutional SBRT study group of Japanese Radiological Society (JRS-SBRTSG), and to discuss how we consider the validity of SBRT for them. Materials/Methods: GGO was defined as hazy opacity that does not obscure underlying bronchial structures or pulmonary vessels at high-resolution computed tomography. We have reviewed 174 patients (89 men, 85 women; mean age, 74 years) treated with SBRT whose lung tumor showed appearance of GGO accompanying solid component ratio to the whole tumor (S/T ratio) less than 50 % in diameter of the tumor and no metastases. SBRT was done because of the pathological proof, positive accumulation on PET study or growth of the tumor. In histology, 69 tumors were adenocarcinoma, 8 were squamous cell carcinoma, 5 were unclassified carcinoma and 92 cases were histology-unproven. The median tumor size was 23 mm (range, 9-53 mm). SBRT was performed using non-coplanar multiple static ports or dynamic arcs. A total dose of 40 -70 Gy (6-15 Gy / fraction) was prescribed in 4-10 fractions. Median biological effective dose (BED) was 108 Gy (range, 72-150 Gy) based on alpha/beta = 10 Gy. Survival, recurrence, and metastases rates were calculated using Kaplan-Meier method. Results: Median follow-up was 32 months. The 3-year local recurrence, regional lymph-node metastases, and distant metastases rates were 3.8%, 4.1%, and 8.6%, respectively. Mean S/T ratios of the subgroup with any recurrences and the subgroup with no recurrence were 22% and 4%, respectively. The rates of cause-specific and overall survival (OS) at 3 years were 98.1% and 85.6%, respectively. The 3-year OS rates of medically operable and inoperable subgroups were 96.2% and 85.6%, respectively. The 3-year OS rate of medically operable and histology-proven subgroup was 88.1%. The 3-year OS of female subgroup was 95.0% and it was significantly better overall survival rate than male. The treatment-related pneumonitis of grade 3 or more was observed in 3.4% of the total patients. Summary and Discussion: Natural course of GGO-containing tumor is much better than that of solid-type tumors. Sublober limited resection would be acceptable in the subgroup of stage I NSCLC if the tumor appears GGO for the most part because they have mostly no invasion nor metastases. SBRT is a so localized treatment only for the tumor that a study comparing SBRT versus limited surgery without regional lymph node resection might have a rationale of randomization for such candidates, however, we have to demonstrate the prognosis and risk factors regarding recurrence, survival, and late toxicity after SBRT with longer follow-up (more than 10 years). In conclusion, the outcomes of SBRT for patients with GGO-containing tumor (solid component was less than 50 % in total diameter) were excellent but some cases had local recurrence or metastases. GGO-containing in most of the tumor seldom produced local progression, lymph node metastases, or distant metastases after SBRT. Although more cases and longer follow up are mandatory, SBRT may be one of the radical treatment options for stage I NSCLC patients with GGO-containing tumor. We hope to have a further discussion regarding the validity of SBRT for them.
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