Association between survival and maximum standardized uptake value of liver metastases detected by 18-fluoro-2-deoxy-d-glucose positron emission tomography-computed tomography in patients with adenocarcinoma of unknown primary origin

The objective of this retrospective study is to investigate the association between survival and maximum standardized uptake values (SUV_max) of liver metastases detected by pre-treatment positron emission tomography-computed tomography (PET-CT) in patients with adenocarcinoma of unknown primary origin (ACUP).

A total of 58 patients with ACUP and liver metastases confirmed histopathologically by liver biopsy and pre-treatment PET-CT were included in this study. SUV_max values of the liver lesions were measured and their association with survival was investigated.

The median age was 62 years; 63.8 % of the patients were males and 36.2 % were females. The median overall survival was calculated as 10.7 months (OS). The median SUV_max of the liver metastases was 8.6. Accordingly, two groups were established: one with values <8.6 and the other with ones ≥8.6. No differences were detected between the two groups with respect to general characteristics. Median OS was 13.2 months in the group with SUV_max <8.6 compared to 7.4 months in the group with SUV_max ≥8.6. This difference was statistically significant (p = 0.033). SUV_max (HR 1.104, 95 % CI 1.013–1.204, p = 0.025), age (HR 1.033, 95 % CI 1.002–1.064, p = 0.034), presence of chemotherapy (HR 2.296, 95 % CI 1.136–4.641, p = 0.021) and LDH level (HR 1.002, 95 % CI 1.001–1.003, p = 0.007) were identified as independent prognostic factors affecting survival in the multivariable analysis. This is the first report evaluating the impact of SUV_max for liver metastases on ACUP patient survival.

The SUV_max of liver metastases evaluated by PET-CT is a prognostic factor influencing survival of patients with ACUP.