Primary tumor SUVmax and ratio of SUVmax to primary tumor size on pretreatment 18F-FDG-PET/CT scan in small cell lung cancer: which is superior for the prognosis?

Abstract

Background The prognostic impact of tumor SUVmax (t-SUVmax) in small cell lung cancer (SCLC) has been questioned with controversial results, and the significance of the ratio of tumor SUVmax to primary tumor size (SUVmax/t-size) in SCLC has yet to be clarified as well. In this study, a retrospective analysis was carried out to figure out the prognostic and predictive powers of pretreatment primary t‑SUVmax and t‑SUVmax/t-size ratio in patients with SCLC.

Methods A total of 349 SCLC patients who underwent pretreatment staging with PET/CT scan were enrolled in the study and analyzed retrospectively.

Results In limited disease SCLC (LD-SCLC), tumor size was significantly associated with both t‑SUVmax (p = 0.02) and t‑SUVmax/t-size (p = 0.0001). Furthermore, performance status, tumor size (p = 0.001), and liver metastasis were significantly associated with t‑SUVmax in extended disease SCLC (ED-SCLC). Moreover, tumor size (p = 0.0001), performance status, cigarette smoking history, and pulmonary/pleural metastasis were found to be correlated with t‑SUVmax/t-size. No associations were found between clinical stages and either t‑SUVmax or t‑SUVmax/t-size (p = 0.9 for both), and t‑SUVmax and t‑SUVmax/t-size values were found to have similar survival rates in both LD-SCLC and ED-SCLC patients. In univariate and multivariate analyses, both t‑SUVmax and t‑SUVmax/t-size were found not to be associated with overall survival (p > 0.05)

Conclusion This study does not advocate the use of either t‑SUVmax or t‑SUVmax/t-size on pretreatment 18F‑FDG-PET/CT scan as prognostic and predictive tools for both LD-SCLC and ED-SCLC patients. Likewise, we did not find that t‑SUVmax/t-size was superior to t‑SUVmax in that respect.