Proton Radiotherapy with Induction Chemotherapy for Locally Advanced Pancreatic Cancer: A Retrospective Analysis of Treatment Strategy and Outcomes.

BACKGROUND AND PURPOSE: The optimal sequencing of chemotherapy and proton therapy (PT) for locally advanced pancreatic cancer (LAPC) remains to be elucidated. This study aimed to evaluate the clinical outcomes of PT in relation to prior chemotherapy and identify the most effective timing for PT within multidisciplinary treatment.

MATERIALS AND

METHODS

This retrospective study reviewed the medical records of 146 patients with LAPC who underwent PT between September 2014 and August 2022 at a single institution. Patients were categorized into three groups: upfront (PT as initial treatment), non-failure (PT after chemotherapy with disease control), and failure (PT after discontinuation of chemotherapy due to disease progression or toxicity). Overall survival (OS) and progression-free survival (PFS) were analyzed from both the initiation of first-line treatment and start of PT.

RESULTS

The median OS for the entire cohort was 20.1 months from the start of initial treatment and 17.1 (95% CI: 13.3-19.0) months from PT initiation. The median OS from first-line treatment in the non-failure, failure, and upfront treatment groups was 30.7 (95% CI: 16.0-42.7), 21.2 (95% CI: 17.8-24.1), and 17.8 (95% CI: 13.9-22.0) months, respectively (P = .030). From PT initiation, the median OS was 26.3 (95% CI: 11.1-40.8), 11.9 (95% CI: 9.3-14.9), and 17.8 (95% CI: 13.9-22.0) months, respectively (P = .001). The non-failure group also exhibited the longest PFS (P = .003). Late grade ≥3 gastrointestinal ulceration was observed in 3.0% of patients, including one case of suspected treatment-related gastric perforation.

CONCLUSION

Improved survival outcomes may be achieved when PT is administered for disease control following induction chemotherapy. These findings highlight the importance of treatment sequencing and patient selection in LAPC management.