Abstract
Simple SummaryStereotactic radiotherapy for localised stage non-small-cell lung carcinoma is an alternative indication for patients who are inoperable or refuse surgery. A study showed that the microscopic tumour extension of non-small-cell lung carcinoma varied according to the histological type, which allowed us to deduce adapted margins for the clinical target volume. The objectives of our retrospective study are. The objective of our study is to measure the microscopic tumour extension of T1N0 or T2aN0 primary lung tumors who underwent surgery. The margin required to cover the microscopic tumour extension with a 95% probability is 4.4 mm and 2.9 mm for squamous cell carcinoma and adenocarcinoma, respectively. Multivariate analysis showed a statistically significant relationship between the maximum microextension distance and size with the shrinkage coefficient.Background: Stereotactic radiotherapy for localised stage non-small-cell lung carcinoma (NSCLC) is an alternative indication for patients who are inoperable or refuse surgery. A study showed that the microscopic tumour extension (ME) of NSCLC varied according to the histological type, which allowed us to deduce adapted margins for the clinical target volume (CTV). However, to date, no study has been able to define the most relevant margins for patients with stage 1 tumours. Methods: We performed a retrospective analysis including patients with adenocarcinoma (ADC) or squamous cell carcinoma (SCC) of localised stage T1N0 or T2aN0 who underwent surgery. The ME was measured from this boundary. The profile of the type of tumour spread was also evaluated. Results: The margin required to cover the ME of a localised NSCLC with a 95% probability is 4.4 mm and 2.9 mm for SCC and ADC, respectively. A significant difference in the maximum distance of the ME between the tumour-infiltrating lymphocytes (TILs), 0–10% and 50–90% (p < 0.05), was noted for SCC. There was a significant difference in the maximum ME distance based on whether the patient had chronic obstructive pulmonary disease (COPD) (p = 0.011) for ADC. Multivariate analysis showed a statistically significant relationship between the maximum microextension distance and size with the shrinkage coefficient. Conclusion: This study definitively demonstrated that the ME depends on the pathology subtype of NSCLC. According to International Commission on Radiation Units and Measurements (ICRU) reports, 50, 62 and 83 CTV margins, proposed by these results, should be added to the GTV (Gross tumour volume). When stereotactic body radiation therapy is used, this approach should be considered in conjunction with the dataset and other margins to be applied.
Highlights
Non-small-cell lung carcinomas (NSCLCs) represent 85% of lung cancer diagnoses [1].Only 15% to 25% of tumours are diagnosed early [2,3], and their management is considerably improved with the development of stereotactic body radiation therapy (SBRT), mini-invasive surgery and interventional radiology.The standard treatment for stage I non-small-cell lung carcinoma (NSCLC) is surgery, reaching 3-year and 5-year overall survival rates of 77.9–79% and 66.1–84%, respectively [4–6]
To delineate targets in radiotherapy, several volumes have been defined by the International Commission on Radiation Units and Measurements (ICRU) reports 50, 62 and 83, including the gross tumour volume (GTV), the clinical target volume (CTV) including microscopic extension (ME) and the planning target volume (PTV)
The mean sizes of ADC and squamous cell carcinoma (SCC) tumours on the computed tomography (CT) scan were 2.15 cm (SD 0.9; min = 0.8; max = 5.3) and 2.33 cm (SD 1.1; min = 0.3; max = 5.4), respectively (Table 2)
Summary
Non-small-cell lung carcinomas (NSCLCs) represent 85% of lung cancer diagnoses [1].Only 15% to 25% of tumours are diagnosed early [2,3], and their management is considerably improved with the development of stereotactic body radiation therapy (SBRT), mini-invasive surgery and interventional radiology.The standard treatment for stage I NSCLC is surgery, reaching 3-year and 5-year overall survival rates of 77.9–79% and 66.1–84%, respectively [4–6]. Non-small-cell lung carcinomas (NSCLCs) represent 85% of lung cancer diagnoses [1]. To delineate targets in radiotherapy, several volumes have been defined by the International Commission on Radiation Units and Measurements (ICRU) reports 50, 62 and 83, including the gross tumour volume (GTV), the clinical target volume (CTV) including microscopic extension (ME) and the planning target volume (PTV). Stereotactic radiotherapy for localised stage non-small-cell lung carcinoma (NSCLC) is an alternative indication for patients who are inoperable or refuse surgery. A study showed that the microscopic tumour extension (ME) of NSCLC varied according to the histological type, which allowed us to deduce adapted margins for the clinical target volume (CTV). To date, no study has been able to define the most relevant margins for patients with stage 1 tumours
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