ESTRO 2024 - Abstract Book

S5231

Radiobiology - Microenvironment

ESTRO 2024

Statistical differences between experimental groups and control were assessed at each dose point using an ANOVA with Dunnett’s multiple comparison test. P-values of less than 0.05 were considered significant.

Results:

A significant increase in clonogenic survival relative to control was seen with post-IR acid exposure at 2Gy (0.42 +/- 0.11 vs. 0.60 +/- 0.04; p=0.001). This was mirrored by proportionately, but not significantly, greater survival for post-IR acid exposure compared to control at 4Gy (0.24+/-0.12 vs. 0.19+/-0.09), 6Gy (0.16+/-0.05 vs. 0.13+/-0.01) and 8Gy (0.12+/-0.01 vs. 0.03+/-0.01). No clear trend in clonogenic survival compared with control was seen for pre- or intra- IR acid exposure at 2Gy (respectively 0.42+/-0.11 & 1.15 (n=1) vs. 0.60+/-0.04), 4Gy (0.24+/-0.12 & 0.18 (n=1) vs. 0.19+/-0.09), 6Gy (0.12+/-0.05 & 0.06 (n=1) vs. 0.13+/-0.01) or 8Gy (0.10+/-0.05 & 0.03 (n=1) vs. 0.03+/- 0.01). Metabolic activity, as assessed by MTT assay, was consistent at each of the assessed dose points (Figure 1).

Conclusion:

The survival fraction of FLO-1 OAC cells at 2Gy is significantly increased by a ten-minute pulse of acidified media post-IR exposure but not by exposure to acid prior to or during IR exposure. Further study is required to determine the extent to which, and how, post-IR acid exposure may contribute to OAC radiation resistance.

Keywords: Oesophageal adenocarcinoma; Acid; pH