14 SCREENING LUNG CANCER WITH MIRNA EXPRESSION PROFILES

CARO 2009 PET as a standard of care. The study objective was to perform a systematic review describing the cost-effectiveness of PET imaging in the staging (ST) of NSCLC and the management of solitary pulmonary nodules (SPN). Materials and Methods: Systematic literature searches were conducted in MEDLINE/PreMEDLINE, EMBASE, and the NHS Database. Measurement of study quality was assessed by the validated Quality of Health Economic Studies (QHES) instrument. Studies with a QHES score less than 75 were excluded. Characteristics including study methodology/ assumptions as well as cost-effectiveness metrics (incremental cost-effectiveness ratio [ICER] based on life years saved and average cost savings per patient [ACSP]) were abstracted. Descriptive statistics were generated with cost amounts converted to a common inflation-adjusted 2007 USD currency. Results: A total of 20 studies met all inclusion criteria including acceptable QHES scores as determined by two reviewers (mean 87.8). The studies were based on the national health care system perspective of eight different countries. Investigations assessed the SPN scenario (n=8), the ST scenario (n=11) and both the SPN and ST scenarios (n=1). Mean assumed cost of PET scanning was $1267 (range $769-$2580) in these studies. Median ICER for SPN and ST was $2039 ($181-$3927) and $4037 ($527-$32618), respectively. Median ACSP for SPN and ST was $518 ($66-$1480) and $1390 ($143-1633), respectively. Conclusion: Reported cost-effectiveness metrics are highly variable and depend on input variables/assumptions including: cost and disease prevalence, diagnostic operating characteristics, the diagnostic strategies assessed, and methodologies utilized. Despite this variation, these studies have consistently concluded that PET has favourable cost effectiveness characteristics compared to non-PET strategies. 14 SCREENING LUNG CANCER WITH MIRNA EXPRESSION PROFILES W. Roa, L. J. Xing, J. Amanie, A. Fairchild, Z. Gabos, T. Nijjar, R. Scrimger, D. Yee Cross Cancer Institute, Edmonton, AB Introduction: Metabolomic studies have been useful in identifying residual changes in patient excretions that are traceable to cancer. Small non-coding microRNAs (miRNAs) are key components of cancer development and considered as potential biomarkers for cancer diagnosis and treatment monitoring. The present study investigated miRNA expression profiles of human cancer cells in order to develop a screening method for lung cancer. Materials and Methods: A series of lung cancer related miRNAs (miR-21, miR-145, miR-155, miR-205 and miR-210) and radiosensitivity related miRNAs (miR-34a and let-7g) were selected as candidates for miRNA expression profiles of radio-resistant and radiosensitive human lung cancer cell lines (A549, and H460 and H1299). For positive and negative controls, breast cancer cell line MCF-7 and normal epidermis cell line GM38, were also used in the experiments. RT-PCR was performed on StepOnePlus (Applied Biosystem, USA). MiRNA expressions of lung and breast cancer cells were compared with normal epidermis cells as well as endogenous controls (u6) using the thermal cycle at threshold. Assessment of miRNA expression profiles were then performed using the hierarchic cluster analysis software (SPSS13, USA). Results: We identified that miR-21, miR-205 and miR-210 were over-expressed, and miR-145 and miR-155 were underexpressed in all cancer cell lines consistently. The miRNA expression profiles in cancer cells were discrete and significantly different from benign cells (p<0.005). There were no significant differences, however, identified between lung cancer and breast cancer cells using the miRNA series (p>0.05). Conclusion: There is potential utility of lung cancer screening with miRNA expression profiles. Current work is focused on the

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sensitivity of such miRNA expression profiles in screening sputum for lung cancer, which can be performed in real time. 15 IMPACT OF DAILY VOLUMETRIC IMAGING IN REDUCING SET-UP MARGINS FOR LUNG CANCER PATIENTS TREATED WITH CONVENTIONALLY FRACTIONATED RADIOTHERAPY J. Higgins1, A. Bezjak1, A. Hope1, T. Panzarella2, W. Li1, T. Craig1, A. Brade1, A. Sun1, J. Cho1, J.P. Bissonnette1 1 University of Toronto, Princess Margaret Hospital, Toronto, ON 2 Princess Margaret Hospital, Toronto, ON Purpose: To determine the impact of different image-guidance (IG) protocols on reducing patient set-up error and planning target volume (PTV) margins using cone-beam computed tomography (CBCT) for lung radiotherapy. Materials and Methods: For 100 patients, daily CBCT data sets (4237 scans) were retrospectively registered to planning scans using automatic bone matching. The geometric accuracy obtained with four hypothetical IG protocols was calculated and compared to our daily IG practice: (a) no IG; (b) 1st 5 days IG, with a mean systematic shift applied to fractions 6+; (c) weekly IG and (d) alternate day IG. For each imaging protocol, the magnitude of set-up error was categorized using systematic (å) and random (s) deviations. The van Herk margin recipe (2.5å + 0.7s) was then used to calculate approximate PTV setup margins required by each imaging protocol. Results: Reductions in systematic error (å) were observed as the proportion of imaged fractions increased from no IG to daily IG in the right-left (RL) å=1.7-0.9mm, superior-inferior (SI) å=2.4-0.7mm, and anterior-posterior (AP) å=1.7-1.0mm directions, respectively. Random error(s) fluctuated little within the four hypothetical protocols but a significant decrease was seen from no IG to daily IG in the RL s=2.91.7mm, SI s=3.8-2.0mm, and AP s=2.4-1.7mm directions, respectively. Population-based set-up margins were 6, 9, 6mm (no IG); 6, 7, 5mm (first five days IG); 5, 7, 5mm (weekly IG); 5, 6, 5mm (alternate IG); and 4, 3, 4mm (daily IG) in the RL, SI and AP directions respectively. With the exception of daily IG, the largest set-up errors and PTV margins were seen in the SI direction for imaging protocols studied. Conclusion: Daily volumetric IG significantly reduces patient set-up error compared to less frequent imaging protocols, especially in the superior-inferior direction. For patients with locally advanced lung disease, PTV set-up margins as small as 4mm may be possible, provided that daily CBCT imaging is used. This has the potential to reduce treatment toxicity without compromising target coverage. 16 A COMPARISON OF TWO IMMOBILIZATION SYSTEMS FOR STEREOTACTIC BODY RADIATION THERAPY (SBRT) OF LUNG TUMOURS K. Han1, P. Basran2, D. Erler2, F. Lochray2, L. Yeung3, I. Poon2, P. Cheung2 1 University of Toronto, Princess Margaret Hospital, Toronto, ON 2 University of Toronto, Odette Cancer Centre, Toronto, ON 3 University of Toronto, Toronto, ON Purpose: No study has directly compared the different immobilization methods used in SBRT for lung tumours. This study aims to compare the efficacy, efficiency and comfort level of two immobilization systems commonly used in lung SBRT: the Bodyfix and the abdominal compression plate (ACP). Methods: From October 2008, patients undergoing SBRT (4852Gy/4f) for medically inoperable Stage I NSCLC or pulmonary metastases were entered on a prospective study. All underwent 4DCT simulation with no abdominal compression (i.e. free breathing), the Bodyfix, and the ACP to assess respiratory tumour motion. For all three 4DCT scans, the same bottom vacuum cushion was used to keep the patient in the same body position. After CT simulation, patients were randomly assigned