Endosonographic assessment of the response of rectal cancer to preoperative radiotherapy endosonographic assessment of the response of rectal cancer to preoperative radiotherapy.

Background/aims: The accuracy of endoluminal ultrasonographic restaging of rectal cancer after chemoradiation has not been extensively studied and its definitive clinical utility has yet to be defined. The aim of the present study is to assess the benefit of endoluminal ultrasonography with Doppler evaluation for rectal cancer restaging after preoperative radiotherapy.

Methodology: Twenty six patients (10 female, 16 males, mean age--58 years) with histologically proven rectal cancer underwent preoperative radiotherapy. All patients were examined by endoluminal (endorectal or endovaginal) ultrasonography. Endosonography was repeated on 13 patients after small fractions preoperative radiotherapy.

Results: The mean transversal diameter of lesions before preoperative radiotherapy established by endoluminal ultrasonography is 33mm +/- 11 mm. After preoperative radiotherapy we detect significant reduction of 33% in the transversal tumor size--mean 23mm +/- 7mm (p < 0.001). After radiation the mean distance from the tumor to the internal anal sphincter increases without statistical significance by 5%: from 59 +/- 18 mm to 62 +/- 16 mm (p = 0.165). Compared to histological data, endosonographic restaging after radiotherapy is accurate in 9/13 (69%) for T parameter and 11/13 (85%) for N. After preoperative radiotherapy tumor sonographic structure is hyperechoic (homogeneous or inhomogeneous)--in 9 patients and only in 4 cases the tumor remains hypoechoic. Power Doppler exam before radiotherapy shows poor vascularization in 5 tumors--(19%). Abundant vascularization is found in 9 cases--(35%). In the remaining 12 patients tumor vascularization is considered as moderate. In 8 out of 13 cases (61.5%) after radiotherapy, vascular signals are less expressed. Lack of vascular alterations on pulse color and power Doppler flow is detected in the remaining 5 patients. No patients have more expressed vascularization on power Doppler examination after radiotherapy.

Conclusion: According to our results the accuracy of endosonographic restaging after radiotherapy is lower for assessment of T criterion and is better for N parameter. Doppler findings are promising in the evaluation of tumor vascularity, respectively its predictive and prognostic values.