The value of endoscopic rectal ultrasound in predicting the lateral clearance and outcome in patients with lower-third rectal adenocarcinoma

BACKGROUND AND STUDY AIMS

The aim of this study was to assess whether preoperative endorectal ultrasound (ERUS) is able to predict histological infiltration of the external anal sphincter or the levator ani muscle in patients with a lower-third rectal neoplasm and so the possibility of treatment by sphincter-saving surgery.

PATIENTS AND METHODS

Between May 1996 and May 2003, 66 patients with a lower-third rectal neoplasm that was staged as uT2 or greater were entered into a prospective evaluation of ERUS. All patients underwent neoadjuvant treatment before surgery.

RESULTS

The first ERUS (ERUS 1) was performed before neoadjuvant treatment; the second ERUS (ERUS 2) was performed between the end of the radiotherapy and the surgery. An abdominoperineal resection was performed mainly when the lower extent of the tumor was within 3.5 cm from the anal verge (P = 0.011), but no correlation was observed between the lateral clearance determined by ERUS 1 and the histological clearance (P = 0.091). After neoadjuvant treatment, the ERUS 2 lateral clearance was significantly correlated with the type of surgery (P = 0.003) and the histological clearance (P < 0.001). With regard to the performance of ERUS 2 for predicting histological infiltration of the external anal sphincter or the levator ani muscle, the sensitivity was 100%, the negative predictive value was 100%, the specificity was 87%, and the positive predictive value was 53%. In a multivariate analysis, the histological clearance and tumor T stage were statistically correlated with disease-free survival (P = 0.035 and P = 0.05, respectively).

CONCLUSIONS

ERUS could help oncologists and surgeons in the management of patients with lower rectal carcinomas. Moreover, ERUS is able to predict lateral histological clearance after neoadjuvant treatment.

Calcium channel modulators of the dihydropyridine family are human pregnane X receptor activators and inducers of CYP3A, CYP2B, and CYP2C in human hepatocytes

The expression of three cytochromes P450 (CYP3A4, CYP2C9, and CYP2B6) was investigated in primary human hepatocyte cultures following treatment with four calcium channel modulators (CCM) of the dihydropyridine family, three antagonists (nifedipine, nicardipine, and isradipine), and one agonist (BK8644). Induction of CYP3A4 was studied by Northern blot, Western blot, and enzymatic activity. Induction began between 1 and 10 microM CCM and was dependent on the presence of dexamethasone (100 nM) in the medium. CYP3A4 mRNA accumulation started only after 16 h of treatment because pregnane X receptor (hPXR) synthesis was needed. Cotransfection experiments showed that the proximal and the distal PXR response elements of the CYP3A4 promoter and hPXR (HepG2 cells) or dexamethasone-induced hPXR (primary hepatocytes) were necessary to obtain full induction. Furthermore, glutathione S-transferase pull-down assays demonstrated that the CCM tested can act as hPXR ligands. In addition, cotransfection experiments in CV1 cells showed that these compounds failed to reverse CAR (constitutively activated receptor) inactivation by androstenol. Finally, 10 microM CCM induced both CYP2C9 and CYP2B6, strengthening the evidence that hPXR is involved in the regulation of these genes. All together, these results widen the field of hPXR activators to a new class of ligand, namely the CCM of the dihydropyridine family.