[Magnetic resonance tomography and endosonography in the preoperative staging of advanced rectal carcinomas after hyperthermoradiochemotherapy]

Comparison of CT, MRI and FDG-PET in response prediction of patients with locally advanced rectal cancer after multimodal preoperative therapy: is there a benefit in using functional imaging?

The aim of this study was to compare CT, MRI and FDG-PET in the prediction of outcome of neoadjuvant radiochemotherapy in patients with locally advanced primary rectal cancer. A total of 23 patients with T3/4 rectal cancer underwent a preoperative radiochemotherapy combined with regional hyperthermia. Staging was performed using four-slice CT (n=23), 1.5-T MRI (n=10), and (18)F-FDG-PET (n=23) before and 2-4 weeks after completion of neoadjuvant treatment. Response criteria were a change in T category and tumour volume for CT and MRI and a change in glucose uptake (standard uptake value) within the tumour for FDG-PET. Imaging results were compared with those of pretherapy endorectal ultrasound and histopathological findings. Histopathology showed a response to neoadjuvant therapy in 13 patients whereas 10 patients were classified as nonresponders. The mean SUV reduction in responders (60+/-14%) was significantly higher than in nonresponders (37+/-31%; P=0.030). The sensitivity and specificity of FDG-PET in identifying response was 100% (CT 54%, MRI 71%) and 60% (CT 80%, MRT 67%). Positive and negative predictive values were 77% (CT 78%, MRI 83%) and 100% (CT 57%, MRI 50%) (PET P=0.002, CT P=0.197, MRI P=0.500). These results suggest that FDG-PET is superior to CT and MRI in predicting response to preoperative multimodal treatment of locally advanced primary rectal cancer.

Comparison of transrectal sonography and double-contrast MR imaging when staging rectal cancer

OBJECTIVE

The aim of this study was the prospective comparison of the diagnostic yield of transrectal sonography and double-contrast MR imaging for preoperative staging of rectal cancer. SUBJECTS AND METHODS. Thirty-nine rectal cancer patients (20 men, 19 women) underwent transrectal sonography performed with a 10-MHz endoanal probe and MR imaging (1.0 T or 1.5 T) using a whole-body coil. After rectal application of a superparamagnetic iron oxide MR contrast agent, T1- and T2-weighted images and gadolinium-enhanced double-contrast images were obtained. The results of examinations were compared with the histology of resected specimens.

RESULTS

Histopathology showed four stage T1, 11 stage T2, 18 stage T3, and six stage T4 tumors using the TNM staging system. Nodal metastases were seen in 16 patients. Transrectal sonography could not be performed in 11 patients because of the high location of the tumor. In the remaining 28 patients, the accuracy of transrectal sonography for T stage was 64% overall (patients not receiving radiation, 69%; patients receiving radiation, 60%) and 70% for N stage. In 39 patients, double-contrast MR imaging correctly identified the T stage with an accuracy of 64% overall (patients not receiving radiation, 75%; patients receiving radiation, 53%) and the N stage with an accuracy of 62%. The assessment of rectal wall penetration (Dukes' classification A versus B) revealed a sensitivity, specificity, and accuracy of 93%, 71%, and 82%, respectively, for transrectal sonography and 100%, 60%, and 85% for MR imaging.

CONCLUSION

If it is technically feasible, transrectal sonography is an accurate method for staging rectal cancer. In proximal or stenotic tumors, double-contrast MR imaging is the method of choice. Diagnostic accuracy of transrectal sonography and MR imaging is high for predicting bowel wall penetration.

[Phase II study on preoperative radio-chemo-thermotherapy in locally advanced rectal carcinoma]

BACKGROUND

Recent studies show that preoperative radio-chemotherapy can increase resectability and local control of locally advanced rectal carcinomas. Additional regional hyperthermia might increase remission rates and tumor response. We therefore tested regional hyperthermia together with radio-chemotherapy in a phase-II study on locally advanced rectal carcinomas.

PATIENTS AND METHODS

Thirty-seven patients with primary advanced stage uT3/T4 rectal carcinomas were treated with preoperative radio-chemo-thermo-therapy. The initial tumor depth was determined using endosonography, CT, and MRI. Radiotherapy was carried out in prone position (on a belly board) using standard techniques, with 5 x 1.8 Gy per week up to 45 Gy at the reference point. 5-Fluorouracil (300 to 500 mg/m2) was administered with low doses of leucovorin (50 mg) on days 1 to 5 and 22 to 28. The patients were treated with regional hyperthermia each week prior to radiotherapy and simultaneously with chemotherapy, using the Sigma 60 ring from the BSD-2000 system. Temperature/position curves and temperature/time curves were recorded in endocavitary (endorectal) catheters in tumor contact and as well in bladder and vagina. Following endosonographic restaging, the operation was carried out 4 to 6 weeks after the end of preoperative therapy and adjuvant chemotherapy continued in four cycles. In cases where tumors were non-resectable, a boost up to 64 Gy was aimed.

RESULTS

Thirty-one of the 37 patients (84%) with primary carcinoma proved locally R0-resectable. In addition we had 1 R1-resection (3%) and 5 non-resectable tumors (13%). Among the resected tumors, 53% experienced a reduction of depth infiltration from the initial endosonographic stage during preoperative therapy. The actuarial survival rate after 4 years is 65% (free of progression 57%). The actuarial 4-year survival rate was particularly favorable for the group of responders. Overall, the preoperative multimodal therapy was well tolerated, and premature termination was only necessary in 1 case (3%). Grade III/IV toxicities in the intestine and skin were reduced as far as possible by field blockings and cooling of the perineal region. They occurred only in 5/37 patients (13%) at the intestine and in 6/37 patients (16%) at the skin. The thermal data were subjected to a statistical analysis. The quality of temperature distribution (T90, cum min T90 > or = 40.5 degrees C) depends on the power level and relative power density. The response (reduction of tumor size or depth infiltration) correlated significantly with quality parameters of the temperature distributions. This dependency is found as a trend for progression-free survival, too.

CONCLUSIONS

Preoperative radio-chemo-thermo-therapy proved to be practical and effective, with encouraging remission rates and excellent local control rates. For this reason, a phase-III study to test regional hyperthermia has been initiated. At the same time, certain technical improvements are still under development for regional hyperthermia.