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Keywords:

  • bone metastasis;
  • FDG-PET;
  • hepatocellular carcinoma;
  • radiotherapy;
  • SUV ratio

Abstract

Aims

To determine the utility of FDG-PET in predicting long-term infield tumour control after RT in patients with metastatic hepatocellular carcinoma (HCC) to bone.

Methods

Among 223 patients with HCC skeletal metastases diagnosed, we reviewed 22 patients with 45 total sites treated with RT who had at least two FDG-PETs prior to and after RT. The median RT dose was 42 Gy (range, 22–48) with a median fraction of 3 Gy (range, 2–8). Helical tomotherapy was generally offered for lesions that received higher RT dose (36%). The intrahepatic control rate in all patients was 73% at the time of referral. The ratio of tumour SUV to blood-pool activity SUV (SUV-ratio) was calculated. The primary end-points were infield progression-free survival (infield-PFS) and infield event-free survival (infield-EFS; recurrent and intractable pain or skeletal-related events).

Results

Among 45 sites, 20 had tumour progression and 21 developed events in the previously treated area. A higher SUV-ratio before RT, SUV-ratio decline and higher radiation dose were independently and significantly correlated with better infield-PFS (both < 0.05). The tumours with a pre-RT SUV-ratio ≥3.0 and SUV-ratio decline ≥40% had significantly better infield-PFS and EFS than those with either a pre-RT SUV-ratio <3.0 or SUV-ratio decline <40% (both < 0.05).

Conclusions

FDG-PET may help to predict outcomes of infield tumour control following palliative RT for treatment of HCC bone metastases. Tumours with low metabolic uptake before RT or with a minor decline in post-RT SUV-ratio showed poor long-term infield tumour control.