Objective and noninvasive detection of sub-clinical lung injury in breast cancer patients after radiotherapy.

AIMS: We employed technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) lung scan to detect sub-clinical lung injury after radiation therapy of 60 female patients diagnosed with right breast cancer.
METHODS: The degree of pulmonary vascular endothelium damage was represented as lung/liver uptake ratios (L/L ratios) calculated on Tc-99m HMPAO lung scan. All patients underwent simple mastectomy and post-operative radiotherapy of approximately 50 Gy. We divided the patients into three groups according to the interval between radiotherapy and lung Tc-99m HMPAO lung scan: Group 1 included 20 patients who received the lung scan within 1-3 months after radiotherapy, group 2 included 20 patients were within 3-9 months after radiotherapy, and group 3 included 20 patients were more than 9 months after radiotherapy. In addition, 20 age-matched normal women were included as the control group.
RESULTS: The L/L ratios were 0.32+/-0.04 for normal controls, 0.59+/-0.10 for group 1, 0.55+/-0.07 for group 2, and 0.34+/-0.04 for group 3, respectively. Based on our preliminary results, we found that sub-clinical lung injury and significantly increased L/L ratio in breast cancer patients received radiotherapy may occur within the first 6 months after radiotherapy. However, the L/L ratio is markedly decreased after 9 months.
CONCLUSION: Our findings concluded that the degree of pulmonary vascular endothelium damage represented as the L/L ratio on Tc-99m HMPAO lung scan has the potential to be a sensitive, objective and noninvasive method to detect sub-clinical lung injury in breast cancer patients received radiotherapy.