Iridium-192 boost improved progression-free survival in unresectable hilar cholangiocarcinoma

KEY POINTS

• The retrospective study included 62 patients with unresectable hilar cholangiocarcinoma treated between 2014 and 2019. All received percutaneous biliary stenting and concurrent chemoradiotherapy; 32 additionally received an iridium-192 brachytherapy boost and 30 received external-beam treatment alone.
• The regimens were not dose-equivalent. The brachytherapy group received 45 Gy in 25 fractions externally plus 20 Gy in four 5-Gy brachytherapy fractions, whereas the comparison group received 60 Gy in 30 fractions externally. Total tumor equivalent dose was approximately 71.6 versus 61.2 Gy.
• At three months, objective response was 93.8% with brachytherapy versus 70.0% without it (p=0.020), while disease-control rates were 100% and 96.7%, respectively.
• Median progression-free survival was 11.2 versus 8.6 months (p=0.032). In multivariable analysis, the combined strategy remained associated with lower progression risk (HR 0.56, 95% CI 0.32–0.97; p=0.039).
• Median overall survival was 14.5 versus 12.2 months (p=0.361), with no significant difference. Distant metastasis was the predominant failure pattern, potentially explaining why better local treatment did not clearly translate into longer survival.
• Median biliary-stent patency increased from 7.3 to 9.8 months (p=0.027). Six-month patency was 78.1% versus 56.7%, and 12-month patency 37.5% versus 20.0%.
• Severe toxicity was comparable: grade ≥3 neutropenia occurred in 12.5% versus 13.3%, and grade ≥3 thrombocytopenia in 15.6% versus 10.0%. Treatment allocation depended on era, anatomy, technical availability and patient preference, and the authors acknowledge that the observed benefit cannot be separated from the higher cumulative tumor dose.

CLINICAL TAKEAWAY

SOURCE

Frontiers in Oncology