ESTRO 2023 - Abstract Book

S587

Monday 15 May 2023

ESTRO 2023

validation cohort (HR = 1.10, 95% CI: 1.05-1.16) (Fig B). The development of neutropenia was not prognostic for patients receiving chemo-RT, suggesting the ALC feedback: cisplatin interaction finding is not related to cisplatin exposure Table

Discovery cohort: n = 964

Validation cohort: n = 608

Variable

Age (years) median (range)

58 (28, 87)

58 (30, 86)

Smoking history – N (%) Never / <10 pyh Ex ( ≥ 10 pyh) Current Unknown TNMv8 stage group – N (%)

285 (30) 385 (40) 281 (29) 13 (1) 309 (32) 197 (20) 173 (18) 87 (9) 35 (4) 163 (17)

309 (51) 159 (26) 134 (22) 6 (1) 232 (38) 85 (14) 106 (17) 60 (10) 20 (3) 105 (17)

1 2 3

4a 4b Unknown

Cisplatin Use – N (%) Yes No Unknown Pre-RT ALC (x109/L) median(range) Lymphocyte MTT (days) Median (range) Lymphocyte feedback Median (range)

527 (55) 364 (38) 73

410 (67) 198 (33) 0 (0)

1.7 (0.4, 4.5)

1.6 (0.2, 14.0)

4.7 (1.6, 11.6) 11.4 (8.6, 16.2)

0.08 (0.03, 0.22)

0.08 (0.01, 0.36)

Figure

Conclusion Patients receiving chemo-RT for OPSCC with low versus high ALC feedback (larger falls in ALC) have improved survival. This appears independent from cisplatin exposure & may represent cisplatin enhancing trafficking of lymphocytes from blood into tumour during RT, adding to increasing evidence of the immunomodulatory effects of cisplatin

MO-0717 Seasonality of radiotherapy efficacy for head & neck cancer patients: MACH-NC/MARCH meta-analyses