Metabolic activity measured by FDG PET predicts pathological response in locally advanced superior sulcus NSCLC.
OBJECTIVE
Pathological complete response and tumor regression to less than 10% vital tumor cells after induction chemoradiotherapy have been shown to be prognostically important in non-small cell lung cancer (NSCLC). Predictive imaging biomarkers could help treatment decision-making. The purpose of this study was to assess whether postinduction changes in tumor FDG uptake could predict pathological response and to evaluate the correlation between residual vital tumor cells and post-induction FDG uptake.


METHODS
NSCLC patients with sulcus superior tumor (SST), planned for trimodality therapy, routinely undergo FDG PET/CT scans before and after induction chemoradiotherapy in our institute. Metabolic end-points based on standardized uptake values (SUV) were calculated, including SUV(max) (maximum SUV), SUV(TTL) (tumor-to-liver ratio), SUV(peak) (SUV within 1 cc sphere with highest activity), and SUV(PTL) (peak-to-liver ratio). Pathology specimens were assessed for residual vital tumor cell percentages and scored as no (grade 3), <10% (grade 2b) and >10% vital tumor cells (grade 2a/1).


RESULTS
19 and 23 patients were evaluated for (1) metabolic change and (2) postinduction PET-pathology correlation, respectively. Changes in all parameters were predictive for grade 2b/3 response. ΔSUV(TTL) and ΔSUV(PTL) were also predictive for grade 3 response. Remaining vital tumor cells correlated with post-induction SUV(peak) (R=0.55; P=0.007) and postinduction SUV(PTL) (R=0.59; P=0.004). Postinduction SUV(PTL) could predict both grades 3 and 2b/3 response.


CONCLUSIONS
In NSCLC patients treated with chemoradiotherapy, changes in SUV(max), SUV(TTL), SUV(peak), and SUV(PTL) were predictive for pathological response (grade 2b/3 and for SUV(TTL) and SUV(PTL) grade 3 as well). Postinduction SUV(PTL) correlated with residual tumor cells.
Departments of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands.
I
I
Bahce
Departments of Surgery, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: c.vos@vumc.nl.
C G
CG
Vos
Departments of Surgery, VU University Medical Center, Amsterdam, The Netherlands; Departments of Cardiothoracic Surgery, VU University Medical Center, Amsterdam, The Netherlands.
C
C
Dickhoff
Departments of Surgery, VU University Medical Center, Amsterdam, The Netherlands; Departments of Pathology, VU University Medical Center, Amsterdam, The Netherlands.
K J
KJ
Hartemink
Departments of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands.
M
M
Dahele
Departments of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands.
E F
EF
Smit
Departments of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
R
R
Boellaard
Departments of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
O S
OS
Hoekstra
Departments of Pathology, VU University Medical Center, Amsterdam, The Netherlands.
E
E
Thunnissen
D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D008297:Male; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D012372:ROC Curve; D012074:Remission Induction; D016896:Treatment Outcome
D019788:Fluorodeoxyglucose F18
NSCLC; PET; PET-pathology correlation; Pathological response; Standardized uptake value; Superior sulcus tumor