Pretreatment positron emission tomography (PET) scan standardized uptake value (SUV) as a prognostic variable for overall survival in limited-stage small cell lung cancer (L-SCLC).

Abstract

7045 Background: PET imaging has been increasingly utilized in L-SCLC. However, the prognostic value of the staging SUV has not been well elucidated. Methods: From 1/2004-12/2008, 59 patients with L-SCLC were treated with definitive chemoradiation at M. D. Anderson Cancer Center and received a pretreatment staging PET scan. The median radiation therapy (RT) dose was 45 Gy in 30 fractions delivered twice daily (range 40.5-61.8 Gy). Thirty two percent of patients (n = 19) underwent induction chemotherapy, though all initial PET scans were taken prior to any treatment. The median value for the maximum SUV of the primary lesion (pSUVmax) was 12.0 (range 1.3-34.6), and for the nodal disease (nSUVmax) it was 11.5 (range 3.1-35.5). Twenty eight percent of patients had assessable follow-up PET imaging within one year of completing treatment. Overall survival (OS) was measured from the end of RT to the date of death or, if not documented, the last follow-up at our institution. Kaplan-Meier analysis was utilized to determine 1, 2, and 3-year estimates of OS. Univariate analysis was then performed to evaluate the effect of pSUVmax and nSUVmax on OS. Results: The median change in pSUVmax after treatment was -63% (range +21 to -90%). At a median follow-up of 16.4 months (range 2.9-68.5 months), 1-, 2-, and 3-year rates of OS were 74%, 60%, and 46%, respectively. On univariate analysis, a pSUVmax of > 13 was of borderline significance (p = 0.05), and a pSUVmax of >14 was statistically significant as a prognostic factor for OS (p < 0.05). A higher pSUVmax was correlated with an improved survival up to a level of 18. At pSUVmax>18, small patient numbers limited analysis. Initial nSUVmax did not correlate with OS. Conclusions: Most patients who receive definitive chemotherapy and RT for L-SCLC experience marked PET scan responses. Unexpectedly, a higher initial pSUVmax was associated with better OS. This finding could be due to improved outcomes with accelerated RT in high-SUV patients, such that there is a more beneficial fractionation for patients with low SUVmax levels in L-SCLC. Individualized treatment may be indicated based on pretreatment SUV. No significant financial relationships to disclose.