Radiation dose mapping and anastomotic complications after trimodality therapy for esophageal cancers.

BACKGROUND AND PURPOSE: There is conflicting evidence with respect to the correlation between neoadjuvant chemoradiation and anastomotic complications following trimodality therapy in patients with esophageal cancer. We aimed to analyze the relationship between their dosimetry and any resulting anastomotic complications. MATERIALS AND METHODS: The medical records of 51 consecutive patients who underwent trimodality therapy between 2007 and 2014 were retrospectively reviewed. We analyzed the differences in the mean dose received by regions of the esophagus relative to the landmark of the azygous vein and the stomach to correlate the development of an anastomotic complication using nonparametric rank-sum tests. RESULTS: Anastomotic leakage and stricture rates were 12% and 22%, respectively. Patients with anastomotic complications received a statistically significant higher mean dose to the esophagus at the level of the azygous vein (0.0 cm) and lower (up to -2.7 cm) (28.4-42.2 Gy vs. 10.3-27.6 Gy, p < 0.04). There were no differences noted in mean gastric doses. Median follow up time was 30.9 months. Median overall survival and disease free survival of our patient cohort was 34.4 months and 22.5 months, respectively. The development of an anastomotic complication did not affect survival outcomes. CONCLUSION: Patients who experienced anastomotic complication after trimodality therapy for esophageal cancer were more likely to have received a higher mean esophageal dose around the proximity of the azygous vein, where intrathoracic anastomoses most commonly occur. Communication between surgical and radiation oncologists regarding the anastomotic location may be an important consideration in planning for trimodality therapy in reducing potential anastomotic complications.

Retinoic acid signaling is essential for formation of the heart tube in Xenopus.

Retinoic acid is clearly important for the development of the heart. In this paper, we provide evidence that retinoic acid is essential for multiple aspects of cardiogenesis in Xenopus by examining embryos that have been exposed to retinoic acid receptor antagonists. Early in cardiogenesis, retinoic acid alters the expression of key genes in the lateral plate mesoderm including Nkx2.5 and HAND1, indicating that early patterning of the lateral plate mesoderm is, in part, controlled by retinoic acid. We found that, in Xenopus, the transition of the heart from a sheet of cells to a tube required retinoic acid signaling. The requirement for retinoic acid signaling was determined to take place during a narrow window of time between embryonic stages 14 and 18, well before heart tube closure. At the highest doses used, the lateral fields of myocardium fail to fuse, intermediate doses lead to a fusion of the two sides but failure to form a tube, and embryos exposed to lower concentrations of antagonist form a heart tube that failed to complete all the landmark changes that characterize looping. The myocardial phenotypes observed when exposed to the retinoic acid antagonist resemble the myocardium from earlier stages of cardiogenesis, although precocious expression of cardiac differentiation markers was not seen. The morphology of individual cells within the myocardium appeared immature, closely resembling the shape and size of cells at earlier stages of development. However, the failures in morphogenesis are not merely a slowing of development because, even when allowed to develop through stage 40, the heart tubes did not close when embryos were exposed to high levels of antagonist. Indeed, some aspects of left-right asymmetry also remained even in hearts that never formed a tube. These results demonstrate that components of the retinoic acid signaling pathway are necessary for the progression of cardiac morphogenesis in Xenopus.

Expression of muscle LIM protein during early development in Xenopus laevis.

We have isolated the Xenopus homologue of Muscle LIM protein (MLP, CRP3) and examined its expression during early embryonic development. MLP is only expressed in the differentiated heart during early development and is expressed in a subset of other striated muscles during later stages. There is no MLP expression during primary myogenesis in the somites, although it is found in adult skeletal muscle.