ESTRO 2024 - Abstract Book

S1656

Clinical - Lung

ESTRO 2024

A subset of patients underwent CCT and echocardiography within 14 days prior to radiotherapy and 4-9 months after the end of radiotherapy.

Heart contours for all participants included all heart chambers and the pericardial sac. Coronary arteries were contoured in the subset of participants who had CCT, using the atlas by Duane et al [4]. Coronary artery and heart mean dose (MHD) were converted to equivalent dose in 2Gy/fraction using an alpha/beta ratio of 3. Difference in blood results at the 3 timepoints were compared using a Kruksall-Wallis test. Differences in imaging metrics between the 2 timepoints were compared using a Wilcoxon signed-rank test. Correlation between bloods and heart dose were compared using multivariable linear regression and between outcome and bloods or imaging using multivariable cox regression.

Results:

136 patients were recruited, 37 of whom had baseline cardiac imaging. Two patients withdrew from the study. Median age was 72 years (52-86 years). Patient and tumour characteristics are shown in table 1.

n=134

SABR (n=56)

Non-SABR (n=78)

Median age

74 years (58-87)

71 years (49-86)

Sex

Male

26 (46%)

44 (56%)

Female

30(54%)

34 (44%)

Stage

1

46 (82%)

13 (17%)

2

5 (9%)

13 (17%)

3

0

52 (66%)

Histology

NSCLC

29 (52%)

50 (64%)

SCLC

0

19 (24%)

No histology

27 (48%)

9 (12%)

Performance Status

0

6 (11%)

19 (24%)

1

17 (30%)

38 (49%)

2

24 (43%)

16 (21%)

3

4 (7%)

0

Median MHD (EQD2)

1.2Gy (0.1-5.9Gy)

9.1Gy (0.2-24.5Gy)

In the non-SABR cohort, HsTnI was significantly higher at the end of radiotherapy than at baseline (p<0.001, fig 1). Change in HsTnI was associated with MHD on multivariable analysis, correcting for iGTV, previous ischaemic heart disease and receipt of chemotherapy. HsTnI returned to pre-radiotherapy levels 4 months after radiotherapy. In the SABR cohort, there was no significant difference in HsTnI between timepoints.

Lymphocyte count fell following radiotherapy in both SABR and non-SABR cohorts. There was no change in NT pro BNP in either cohort over the 3 timepoints (fig 2).