Survival and Toxicity in Patients With Unresectable or Inoperable Biliary Tract Cancers With Ablative Radiation Therapy Versus Nonablative Chemoradiation.

PURPOSE

Conventional chemoradiation (CCRT) is inadequately effective for the treatment of unresectable or inoperable biliary tract cancers (UIBC). Ablative radiation therapy (AR), typically defined as a biologically effective dose (BED) ≥80.5 Gy, has shown some promise in terms of local control and survival in these patients. We compare the efficacy and toxicity of AR to non-AR in UIBC patients.

METHODS AND MATERIALS

Patients with UIBC treated with stereotactic body radiation therapy (SBRT; n = 18) or CCRT (n = 28) between 2006 and 2021 were retrospectively analyzed. The associations of treatment, BED groups, selected characteristics with overall survival (OS), progression-free survival (PFS), and local control were estimated separately using Cox proportional hazards regression. Toxicity was scored using Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

Median dose fractionation was 60 Gy in 5 fractions (median BED, 127 Gy) for SBRT and 50 Gy in 25 fractions (median BED, 64 Gy) for CCRT. The median follow-up of the entire cohort was 11.5 months. The 1-year OS rate was 62% for BED <80.5 versus 66% for BED ≥80.5 ( = .069). The 1-year PFS rate was 24% for BED <80.5 and 29% for BED ≥80.5 ( = .050). The 1-year local control rate was 20% for BED <80.5 and 41% for BED ≥80.5 ( = .097). BED as a continuous variable ( = .013), BED ≥100 Gy ( = .044), and race (white versus nonwhite) ( = .037) were associated with improved overall mortality. BED ≥80.5 Gy ( = .046), smaller tumor size (<5 cm; = .038) and N0 disease ( <.0001) were associated with improved disease progression rates. Local control was improved in patients with N0 disease compared with N1 disease ( <.0001). Both treatments were well tolerated; there was no difference in acute and late toxicity between AR and non-AR.

CONCLUSIONS

In this review, there was improved PFS with BED ≥80.5 Gy with a trend toward OS benefit. BED ≥80.5 Gy was achieved mostly through SBRT and was well tolerated. AR could be considered a more effective treatment modality than CCRT in patients with UIBC.