Chemoradiation of rectal cancer.

The treatment of locally advanced rectal cancer is a challenge. Surgery, chemotherapy and radiotherapy comprise the multimodal therapy that is administered in most cases. Therefore, a multidisciplinary approach is required. Because this cancer has a high rate of local recurrence, efforts have been made to improve clinical outcomes while minimizing toxicity and maintaining quality of life. Thus, total mesorectal excision technique was developed as the standard surgery, and chemotherapy and radiotherapy have been established as neoadjuvant treatment. Both approaches reduce locoregional relapse. Two neoadjuvant treatments have emerged as standards of care: short-course radiotherapy and long-course chemoradiotherapy with fluoropyrimidines; however, long-course chemoradiotherapy might be more appropriate for low-lying neoplasias, bulky tumours or tumours with near-circumferential margins. If neoadjuvant treatment is not administered and locally advanced stage is demonstrated in surgical specimens, adjuvant chemoradiotherapy is recommended. The addition of chemotherapy to the treatment regimen confers a significant benefit. Adjuvant chemotherapy is widely accepted despite scarce evidence of its benefit. The optimal time for surgery after neoadjuvant therapy, the treatment of low-risk T3N0 neoplasms, the convenience of avoiding radiotherapy in some cases and tailoring treatment to pathological response have been recurrent subjects of debate that warrant more extensive research. Adding new drugs, changing the treatment sequence and selecting the treatment based on prognostic or predictive factors other than stage remain experimental.

Comparison of two models for evaluation histopathology of experimental renal ischemia.

Renal ischemia/reperfusion (I/R) injury is one of the frequent causes of acute renal failure (ARF) due to the complex, interrelated sequence of events, that result in damage to and death of kidney cells. Cells of the proximal tubular epithelium are especially susceptible to I/R injury, leading to acute tubular necrosis, which plays a pivotal role in the pathogenesis of ARF. Several models have been explicated to assess morphological changes, including those of Jabonski et al. and Goujon et al. We compared the 2 models for histopathological evaluation of 30- or 120-minute periods of renal ischemia followed by 24-hour reperfusion in rats. Several changes were observed after application of the 2 models: proximal tubular cell necrosis, loss of brush border, vacuolization, denudation of tubular basement membrane as a consequence of flattening of basal cells, and presence of intratubular exfoliated cells in the lumen of proximal convoluted tubules at various stages of degeneration (karyorexis, kariopyknosis and karyolysis). Evaluating tubular lesions after 2 periods of experimental ischemia with light microscopy allowed us to conclude that the Goujon classification better characterized the main changes in cortical renal tubules after ischemia.