Baseline tumor oxygen saturation correlates with a pathologic complete response in breast cancer patients undergoing neoadjuvant chemotherapy
Menée sur 42 patientes atteintes d'un cancer du sein, cette étude évalue l'association entre le niveau tumoral de saturation en oxygène, mesuré par une technique de spectroscopie optique, et la réponse à une chimiothérapie néoadjuvante
Tissue hemoglobin oxygen saturation (i.e. oxygenation) is a functional imaging endpoint that can reveal variations in tissue hypoxia which may be predictive of pathological response in subjects undergoing Neoadjuvant Chemotherapy (NCT). In this study we used Diffuse Optical Spectroscopic Imaging (DOSI) to measure concentrations of oxyhemoglobin (ctO2Hb), deoxy-hemoglobin (ctHHb), total Hb (ctTHb = ctO2Hb + ctHHb) and oxygen saturation (stO2= ctO2Hb/ctTHb) in tumor and contralateral normal tissue from forty-one patients with locally advanced primary breast cancer. Measurements were acquired prior to the start of neoadjuvant chemotherapy. Optically derived parameters were analyzed separately and in combination with clinical biomarkers to evaluate correlations with pathologic response. Discriminant analysis was performed to determine the ability of optical and clinical biomarkers to classify subjects into response groups. Twelve (28.6%) of 42 tumors achieved pCR and 30 (71.4%) were non-pCR. Tumor measurements in pCR subjects had higher stO2 levels (median 77.8%) than those in non-pCR individuals (median 72.3%, p = 0.01). There were no significant differences in baseline ctO2Hb, ctHHb, and ctTHb between response groups. An optimal tumor oxygenation threshold of stO2 = 76.7% was determined for pCR vs. non-pCR (sensitivity = 75.0%, specificity = 73.3%). Multivariate discriminant analysis combining estrogen receptor (ER) staining and stO2 further improved the classification of pCR vs. non-pCR (sensitivity = 100% specificity = 85.7%). These results demonstrate that elevated baseline tumor stO2 are correlated with a pathologic complete response. Non-invasive DOSI scans combined with histopathology subtyping may aid in stratification of individual breast cancer patients prior to NCT.
Cancer Research , résumé, 2012