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Early PET/CT scans for assessing treatment responses of non-small cell lung cancer for SBRT boost: what to do with scans from multiple scanners
Ronald C. McGarry, Jonathan Feddock, Partha Sinha, Gary Conrad, Brent J. Shelton, Li Chen, Susanne M. Arnold and John Rinehart

Chemoradiation remains the standard of care for the nonsurgical treatment of advanced non-small cell lung cancer (NSCLC) but local recurrence rates of 30-40% are documented. We examined the early PET/CT responses of NSCLC treated with standard chemoradiation in a prospective single institutional trial of early 18F-2-deoxy-D-glucose-PET/CT scans to help define patients appropriate for dose escalation with SBRT.

48 patients with stage IIA, IIB or IIIA-B NSCLC with no or non-bulky (</= 3.0 cm) lymphadenopathy were included. Approximately one month following chemoradiation, PET-CT was performed to assess responses. Since many patients came from outside facilities, the ability to directly compare pre- and post therapy PET/CT SUV values is compromised. Thus, patients had their pre- and post-chemoradiation PET/ CT SUV’s assessed where possible, but also reviewed in a blinded manner by two experienced nuclear medicine physicians who scored the results on a subjective scale of FDG uptake to assess treatment responses. A high level of agreement was found between the reading nuclear medicine physicians: 0.76 (95% CI of 0.6 to 0.92). Disease progression occurred in 16% of scans including new metastatic or regional failures. 77% of patients had significant improvement in FDG uptake in the primary tumor but only 4.2% had complete resolution. Mediastinal adenopathy had resolved or significantly improved in 90%. This good, but not complete reduction of FDG uptake in the primary tumor suggests that it may be an appropriate target for local intensified radiation boost.

Keywords: lung cancer, chemoradiation, PET scan, response to treatment

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