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OA05 - Treatment Advances in SCLC (ID 373)
- Event: WCLC 2016
- Type: Oral Session
- Track: SCLC/Neuroendocrine Tumors
- Presentations: 1
OA05.07 - Prognostic Value of Circulating Tumour Cells in Limited-Disease Small Cell Lung Cancer Patients Treated on the CONVERT Trial (ID 5431)
14:20 - 15:50 | Author(s): F. Fernandez-Gutierrez
Circulating tumour cells (CTCs) are prevalent in patients with small cell lung cancer (SCLC) (Hou et al. JCO 2012) but their clinical utility is not known for patients with limited disease (LD) who receive concurrent chemoradiation. Here we report on a patient subgroup who underwent CTC analysis and treatment on the Concurrent ONce-daily (OD) VErsus Twice-daily (BD) RadioTherapy (CONVERT) trial (Faivre-Finn Proc. ASCO 2016) that demonstrated a non-significant difference in the primary endpoint of two-year survival for the OD (51%) and BD (56%) arms.
Blood samples (7.5mls) were collected at baseline, prior to any treatment from patients who were enrolled to the CONVERT trial at The Christie Hospital site, Manchester, UK. CTCs were enumerated prospectively using the Cellsearch platform. Patients were randomised 1:1 to receive 45Gy in 30 twice-daily fractions over 3 weeks (Arm 1) or 66Gy in 33 once-daily fractions over 6.5 weeks (Arm 2) starting on day 22 of cycle 1 chemotherapy (4 to 6 cycles of Cisplatin 25mg/m2 days 1-3 or 75mg/m2 day 1 with Etoposide 100mg/m2 days 1-3), followed by prophylactic cranial irradiation if indicated. Radiotherapy planning was with a 3D conformal technique or intensity modulated radiotherapy. Staging by Positron Emission Tomography (PET) was permitted. Standard statistical methods were used to examine associations between CTC number (CTC#), clinical factors and outcomes.
Of 547 patients randomised between April 2008 and November 2013, 79 patients (41 in Arm1 and 38 in Arm 2) underwent CTC enumeration (CTC subgroup). The clinical demographics and median overall survival (OS) of the CTC subgroup did not differ significantly from the overall study population. The median number (range) of CTCs per 7.5mls blood for all 79 patients was 1 (0-3750) and for arm 1 and arm 2 patients respectively, 12 (0-164) and 158 (0-3750) (p=0.495). There was a trend for association of CTC# with higher TNM stage. CTC# was significant for survival in univariate and multivariate analysis. The median (95% CI) OS for ≥15 CTCs (n=18) was 6.01 (4.2-11.5) months compared to 30.77 (19.7-39.3) months for < 15 CTCs (n=61), p <0.001. The positive predictive value of CTC# ≥15 for survival ≤ 2 years is 100%, and ≤ 1 year is 72%. CTC# also predicted for worse outcome in patients who had undergone PET staging.
CTC# is highly prognostic for poor survival in patients with LD-SCLC, treated with concurrent chemoradiotherapy, and could aid treatment decision making for this disease.
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