Role of upper abdominal reirradiation for gastrointestinal malignancies: a systematic review of cumulative dose, toxicity, and outcomes on behalf of the Re-Irradiation Working Group of the Italian Association of Radiotherapy and Clinical Oncology (AIRO).

Purpose: Abdominal recurrences of gastrointestinal malignancies are common. Evidence in clinical studies has shown that re-irradiation (Re-I) is tolerable and efficient in different tumor locations. In contrast, little clinical data are available on normal long-term Re‑I tolerance doses. A systematic review of upper abdominal Re‑I was performed with the aim of exploring the cumulative dose, toxicity, and outcomes.

Methods: A computerized search was undertaken in MEDLINE, EMBASE, OVID, and the Cochrane database. Only studies reporting toxicity and/or outcomes were taken into consideration. To improve the comparability of the different Re‑I regimens and assess the relationship between Radiotherapy (RT) dose and toxicity, the equivalent dose in 2‑Gy fractions was calculated according to the linear quadratic model.

Results: Sixteen studies met the inclusion criteria, with the total patients numbering 408. Median follow-up Re‑I ranged from 5.9 to 45 months. The median time elapsed since previous RT treatment was 15 months (2-162 months). Re‑I prescription doses were variable (22.5 Gy in 3 fractions to 126.5 Gy with I). Cumulative doses calculated for acute- and late-responding tissues ranged from 67.25 to 136 Gy and 30.3 to 188.38 Gy, respectively. Comprehensively, the pooled ≥G3 toxicity was 12% (95%CI: 7.6-19%). The overall 1‑year survival and local recurrence-free survival rates were 53.7% (95%CI: 45.6-63.2%) and 66.5% (95% CI: 58.7-75.4%), respectively. Pain improvement was reported in 66.9% of patients.

Conclusion: Due to limited evidence as a result of the retrospective design of the majority of the studies, our review suggests that upper abdominal Re‑I is effective in terms of local control and palliation, with a moderate rate of severe toxicities.