Doxorubicin-based chemotherapy and radiation increase cardiac perfusion changes in patients treated for left-sided breast cancer

a severity 1.5 SD below the mean was quantitatively analyzed for the territories of the left anterior descending (LAD), left circumfl ex (LCX) and right coronary (RCA) arteries based on computer assisted polar map reconstruction (PMR), i.e. bull’s-eye-view. Changes in perfusion were correlated with percent of the SPECT-defi ned LV incidentally irradiated to 25 Gy (range: 0-32%). The results from the quantitative PMR-analyses were compared with the standard semi-quantitative visual SPECT MPI analyses by nuclear medicine radiologist (12-segment model; severity score 0-3) (summed rest score-SRS). Results: In the LAD-territory, there was a mean increase in PMR perfusion defects of 13% at 6 mos. an d7%a t 12mos. compared to baseline (Friedman ANOVA, P0.006). No differences in perfusion were found in the LCX- or the RCAterritories at 6 or 12 mos. compared to base line. A statistically signi fi cant association between perfusion defects in the LAD-territory at 6 mos. and percent irradiated LV was present for the SRS-method (Spearman Correlation, P0.001), and a trend for association was found in the PMR-analysis (P0.10). When the results from the PMR- and SRS-analyses of the LAD-territory at 6 mos. were compared, an association in the directional trend of the perfusion changes was found (Gamma Statistics, P0.001). The results were unchanged when controlled for the potential effects of co-variates. Conclusions: Tangential photon beam RT in patients with left-sided BC was associated with perfusion defects in the vascular distribution corresponding to the LAD. The percent of LV demonstrating perfusion changes appeared to be of a similar magnitude as the percent incidentally irradiated LV volume among the majority of patients, suggesting that the defects at 6-12 mos. could be manifested via small vessel- rather than coronary artery dysfunction. The PMR- and SRS-methods provided similar results in the LAD territory, implying that the PMR-technique could be a useful compliment to the standard SRS-method for objective quantifi cation of intra patient changes over time following BC irradiation. Up-dated results including data from 18 mos. PMR-analyses will be presented at the meeting.