2023 World Conference on Lung Cancer (Posters)-P1.28. Cessation of Marrow Proliferation on FLT-PET with Low RT Doses During ChemoRT for NSCLC Correlates with Lymphocyte Decline

P1.28. Cessation of Marrow Proliferation on FLT-PET with Low RT Doses During ChemoRT for NSCLC Correlates with Lymphocyte Decline - PDF(Abstract)

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This study investigated the correlation between bone marrow proliferation and lymphocyte decline during chemoradiotherapy (chemoRT) for non-small cell lung cancer (NSCLC). The researchers obtained serial 18F-Flurothymidine PET (FLT-PET) scans from patients receiving chemoRT as part of a clinical trial. They hypothesized that radiation-induced ablation of bone marrow would be associated with a reduction in lymphocytes. <br /><br />The study included 28 patients with locoregionally advanced NSCLC who underwent radical chemoRT treatment. The researchers analyzed baseline, week 2, and week 4 FLT-PET scans and correlated changes in FLT marrow uptake with local radiation dose and changes in blood counts. They used MIM software to segment the skeleton and define volumes of interest (VOIs) based on FLT uptake. The lowest radiation dose at which FLT uptake in the bone marrow became visually unapparent on the week 2 and week 4 FLT-PET scans was determined for each patient. The researchers then produced dose-response curves for radiation dose vs marrow FLT uptake.<br /><br />The results showed that FLT uptake ceased in bone marrow volumes exposed to 4 Gy on the week 2 and week 4 FLT-PET scans. Lymphocyte counts steadily declined during chemoRT. There was a strong correlation between the estimated percentage of proliferating bone marrow ablated by radiation and the decline in lymphocyte counts from baseline to week 4. This correlation was weaker at week 2, suggesting that more time was needed for the relationship between irradiated marrow and lymphocyte decline to become apparent. The relationship between the percentage of marrow ablated and lymphocyte counts was roughly linear.<br /><br />In conclusion, this study found that FLT-detected bone marrow proliferation decreased with increasing local radiation doses during chemoRT for NSCLC and ceased with doses higher than 4 Gy. The percentage of marrow ablated on the week 4 FLT-PET scans was strongly correlated with lymphocyte decline. These findings suggest that bone marrow is at risk of toxicity during chemoRT for NSCLC.

Asset Subtitle

Michael MacManus

Meta Tag

Speaker Michael MacManus

Topic Local-Regional NSCLC

Keywords

bone marrow proliferation

lymphocyte decline

chemoradiotherapy

non-small cell lung cancer

18F-Flurothymidine PET

FLT-PET scans

radiation-induced ablation

blood counts

dose-response curves

toxicity