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To perform a retrospective analysis of survival, local–regional control and the effect of prognostic factors in 61 non-small cell lung cancer patients who were treated with postoperative radiotherapy (PORT) by a linear accelerator (LINAC).
Material and methods
A total of 50–66 Gy PORT with a fractional dose of 1·8–2 Gy was administered to 24 patients (24·5%) for surgical margin positivity, 33 patients (54%) for mediastinal lymph node involvement and 13 patients (21·5%) for both mediastinal lymph node involvement and positive surgical margins.
Results
Median follow-up was 17 months, and the median survival and median distant metastasis-free survival were 25 and 19 months, respectively. Local-regional progression was observed in 10 patients (16·4%). Treatment modality (2D/3D) (p=0·021), tumour size >4 cm (p=0·004), surgical margin positivity (p=0·001), and left lung localisation of the tumour (p≤0·05) were the prognostic factors in terms of survival.
Conclusions
A survey of the literature shows that, without PORT, local recurrence or progression rates increase while overall survival rates decrease. In this study, only patients with PORT are studied and the results show that the local progression and overall survival rates are comparable with literature of LINAC-based PORT. In the case of overall survival, 3D treatment shows better results than 2D treatment modality.
To compare intensity-modulated radiation therapy (IMRT) treatment planning between using positron emission tomography/computed tomography (PET/CT) and CT for target volume delineation in patients with non-small cell lung cancer (NSCLC).
Methods
Nine NSCLC patients with PET/CT images were enrolled into this study. Gross tumour volumes (GTVs) were delineated by the PET visual assessment (PETvis), the automated PET (PETauto), standardised uptake value (SUV)>2·5 (PET2·5) and threshold 40% SUVmax (PET40), and CT-based method. For each patient, two IMRT treatment plans based on CT and PET/CT delineation were performed. The target coverage and the dose–volume parameters for organs at risk were analysed.
Results
The PETauto referred to PET40 when SUVmax<7 and PET2·5 when SUVmax≥7. The mean GTVs were 15·04, 15·7 and 15·14 cc for PETauto, PETvis and CT based, respectively. The GTV of PETauto was not different from PETvis (p=0·441) and CT based (p=0·594). Based on CT delineation in IMRT planning, only 34% of the cases had sufficient PET/CT planning target volumes coverage, whereas the organs at risk dose parameters were not statistically significant (p>0·05).
Conclusions
PET/CT enables more accurate assessment of tumour delineation for NSCLC, therefore improve target coverage in IMRT plan.
To establish whether the use of a passive or active technique of planning target volume (PTV) definition and treatment methods for non-small cell lung cancer (NSCLC) deliver the most effective results. This literature review assesses the advantages and disadvantages in recent studies of each, while assessing the validity of the two approaches for planning and treatment.
Methods
A systematic review of literature focusing on the planning and treatment of radiation therapy to NSCLC tumours. Different approaches which have been published in recent articles are subjected to critical appraisal in order to determine their relative efficacy.
Results
Free-breathing (FB) is the optimal method to perform planning scans for patients and departments, as it involves no significant increase in cost, workload or education. Maximum intensity projection (MIP) is the fastest form of delineation, however it is noted to be less accurate than the ten-phase overlap approach for computed tomography (CT). Although gating has proven to reduce margins and facilitate sparing of organs at risk, treatment times can be longer and planning time can be as much as 15 times higher for intensity modulated radiation therapy (IMRT). This raises issues with patient comfort and stabilisation, impacting on the chance of geometric miss. Stereotactic treatments can take up to 3 hours to treat, along with increases in planning and treatment, as well as the additional hardware, software and training required.
Conclusion
Four-dimensional computed tomography (4DCT) is superior to 3DCT, with the passive FB approach for PTV delineation and treatment optimal. Departments should use a combination of MIP with visual confirmation ensuring coverage for stage 1 disease. Stages 2–3 should be delineated using ten-phases overlaid. Stereotactic and gated treatments for early stage disease should be used accordingly; FB-IMRT is optimal for latter stage disease.
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