Prognostic significance of 18 F-fluorodeoxyglucose - positron emission tomography after treatment in patients with limited stage small cell lung cancer.

Objective: Small cell lung cancer (SCLC) represents 15% to 25% of lung cancers. Despite favorable initial treatment response rates, recurrence is likely and long-term prognosis dismal. Accurate measurement of therapy response is critical to determine which patients might be spared additional treatment, and potential side effects. (18)F-fluorodeoxyglucose positron emission tomography (PET) may help distinguish necrotic or fibrous tissue from residual cancer, thus informing further treatment and prognosis. DESIGN/SETTING/PARTICIPANTS AND METHODS: Retrospective chart review study of limited stage SCLC patients with PET scanning within 4 months post-chemotherapy at Marshfield Clinic, Marshfield, Wisconsin. Diagnosis of SCLC occurred from December 1, 2001 through December 31, 2007.

Results: Twenty-two patients (approximately 7%) had post-treatment PET: 11 positive, 11 negative. Median duration from last chemotherapy to PET was 36 days (range, 3 to 125 days). Median follow-up for all patients was 34.4 months (range, 6.8 to 65.9 months). Estimated median progression-free survival for all patients was 8.1 months (95% confidence intervals [CI], 4.3 to 11.9 months), 10.5 months for PET negative (95% CI, 8.1 to >57.8 months) and 4.3 months for PET positive patients (95% CI, 2.8 to >7.2 months) (P<0.007, log-rank test). Median survival for all patients was 19.2 months (95% CI, 10.3 to >65.8 months). Estimated median survival for PET negative patients was longer than PET positive (29.2 versus 10.3 months, P=0.10).

Conclusion: Post-treatment PET, prognostically significant, may be underutilized.