Rectal imaging and cancer

Diagnostics of rectal cancer: endorectal ultrasound

In rectal cancer, accurate preoperative staging is essential to adequately select patients for different therapeutic regimes. Endosonography has been proven to be an accurate staging modality in multiple prospective studies. A recent large retrospective study, however, has cast doubt on the actual accuracy of endorectal ultrasound for staging rectal cancer in everyday clinical routines. The results of endosonographic staging of rectal tumours over a period of 10 years at the Department of Surgery of the University of Heidelberg are presented. In a first time period, 424 patients with rectal cancer were staged by endosonography and the data recorded prospectively. The examinations were exclusively done by four surgeons with high experience and scientific interest in endosonography. The second time period comprises 332 patients with rectal tumours (including adenomas) having undergone endosonography by six different examiners after introduction of this staging method into the clinical routine. The data here were analysed retrospectively. Accuracy, sensitivity, specificity, and positive and negative predictive values were calculated for the T and N classifications for both series. In the second series, eight factors which have been postulated to influence staging accuracy in the literature were included in a regression analysis in order to identify relevant factors for staging inaccuracies. Accuracy for staging of the T classification was 81% in the first series versus 71.7% in the second series. In the regression analysis of the second series, status post-chemoradiation proved to be the most significant factor for staging inaccuracy (p < 0.0002). When excluding all patients having undergone chemoradiation, the accuracy for staging of the T classification rose to 76%. A major problem of endosonography in this second series was overstaging; the T category was overestimated in 76 cases (22.9% of patients). The main error here was overstaging of adenomas as cancerous lesions (45.5% of all adenomas) and T2-cancers as more advanced cancers (42.2% of all T2-cancers). When excluding the adenomas from this analysis, the accuracy increased to 73.5%. Accuracy for staging of the N classification was 76% in the first series versus 71% in the second series. Status post-chemoradiation again was a relevant factor (p < 0.0003); when excluding these patients the accuracy increased to 73%. The accuracy of endosonography for rectal tumours decreases after introduction of the method into the everyday clinical routine. Nonetheless, apart from magnetic resonance imaging with an endorectal coil, rectal endosonography is still the most accurate staging modality for rectal tumours and allows adequate selection of patients for different therapeutic regimes. As the major problem of rectal endosonography is overstaging, more patients are likely to undergo overtreatment rather than undertreatment. Endosonography is inaccurate in staging patients having undergone chemoradiation.

The utility of routine preoperative computed tomography scanning in the management of veterans with colon cancer

BACKGROUND

The aim of this study is to assess the clinical utility of routine preoperative computed tomography (CT) scanning in patients with cancer of the intraperitoneal colon.

METHODS

From November 1997 to June 2001, all patients at VA Puget Sound Healthcare System with a diagnosis of colon cancer were referred for a preoperative CT scan. Medical records and operative notes were reviewed to determine the influence of preoperative CT on clinical management.

RESULTS

Seventy patients received a CT per protocol. Preoperative CT provided information that was used in treatment planning and management in 26 (37%) cases. However, if preoperative scans had not been performed, the clinical management would have been definitively altered in only 13 (19%) patients.

CONCLUSIONS

Although these data suggest potential benefit for routine preoperative CT scanning, we believe additional study, including cost analysis, should precede the adoption of CT scanning as a routine preoperative study in patients with colon cancer.

Management of locally advanced rectal cancer

The treatment of rectal cancer typically involves a multidisciplinary approach. A minority of patients will have tumors that are full thickness, involve adjacent structures, or have metastatic disease to regional lymph nodes. The combination of adjuvant therapy and surgical resection is the mainstay of treatment for locally advanced carcinoma of the rectum. This article will review the role of adjuvant chemotherapy and radiotherapy in patients with high risk tumors. The operative considerations in advanced rectal cancers will be reviewed. In particular, the role of mesorectal excision and exenterative surgery will be discussed.

Chemoradiation for rectal cancer: current methods

The options available for the surgeon treating patients with rectal cancer have multiplied over the last decade, allowing varied approaches to the disease for individual patients. The development of effective adjuvant therapy in the form of radiotherapy and chemotherapy has led to exciting results-and yet more questions to be answered. The decision to employ adjuvant therapy has led to the development of better staging modalities to improve patient selection for the various treatment protocols. The basic issue of timing of therapy-preoperative vs. postoperative-remains hotly contested, and good, prospective, randomized trials are needed before the questions can be answered. The utility of preoperative multimodality therapy in the downstaging of tumors to make curative resection or sphincter preservation possible must be examined. Advances in surgical therapy have been significant, and groups have reported excellent results with total mesorectal excision (TME) in patients without the addition of adjuvant therapy. Other important surgical issues include ultralow anterior resections with colo-anal or J-pouch anal anastomosis, and the efficacy of sphincter preservation through local excision of invasive rectal cancers with or without adjuvant therapy. Each of these issues needs further study and will have great impact on the treatment of rectal cancer as further experience is gained.