Predictive value of pretreatment metabolic activity measured by fluorodeoxyglucose positron emission tomography in patients with metastatic advanced gastric cancer: the maximal SUV of the stomach is a prognostic factor

Purpose

Few studies have evaluated metabolic activity by ¹⁸F-FDG PET as a prognostic factor in advanced gastric cancer (AGC). We investigated its prognostic role in metastatic AGC.

Methods

We enrolled 82 patients with metastatic AGC, who were treatment-naive and underwent pretreatment ¹⁸F-FDG PET/CT scanning. In each patient, the maximal standardized uptake value (SUVmax) was measured in each target lesion. Stomach_SUVmax was defined as SUVmax in the stomach, while Total_SUVmax was defined as the highest SUVmax among all the target lesions.

Results

The stomach was the organ most frequently displaying the highest SUVmax among all the target lesions (in 67.1?% of patients). A Total_SUVmax value of 11.5 was the value with the maximum sum of sensitivity and specificity from receiver-operating characteristic curves for progression-free survival (PFS). PFS was significantly longer in patients with a Total_SUVmax value <11.5 than in those with a Total_SUVmax value ≥11.5 (P?=?0.023); however, overall survival (OS) was not (P?=?0.055). A Stomach_SUVmax value of 6.0 was derived by similar methods. PFS and OS were significantly longer in those with a Stomach_SUVmax value <6.0 than in those with a Stomach_SUVmax value ≥6.0 (P?=?0.001 and P?=?0.006, respectively). Furthermore, those with a low Total_SUVmax and those with a low Stomach_SUVmax showed better chemotherapeutic responses (P?=?0.016 and P?=?0.034, respectively). Among patients with histologically undifferentiated carcinomas, those with lower Total_SUVmax and those with lower Stomach_SUVmax showed longer median PFS (P?=?0.027 and P?=?0.005, respectively) and OS (P?=?0.009 and P <0.001, respectively). Multivariate analysis demonstrated Stomach_SUVmax as an independent predictor of PFS (P?=?0.002) and OS (P?=?0.038).

Conclusion

Pretreatment metabolic activity may be a useful prognostic marker in patients with metastatic AGC undergoing palliative chemotherapy. Notably, Stomach_SUVmax was the single, most robust factor predicting prognosis.