Contemporary Imaging for Colorectal Cancer
Section snippets
Rationale for preoperative imaging
Accurate preoperative staging of colorectal cancer includes identification of early and advanced disease, which facilitates patient care. The goal of surgical treatment is to assure complete oncologic resection while maintaining the highest possible quality of life for the patient. Factors such as tumor location and size, extent of bowel wall penetration by tumor, involvement of locoregional lymph nodes, and the presence or absence of distant metastatic disease all affect treatment. Early
Imaging the primary lesion and locoregional disease
CT scan is the imaging study most commonly used preoperatively to detect extracolonic metastatic disease and to characterize the extent of locally advanced tumors. CT also detects complications such as obstruction, fistula, and perforation. Performed in the preoperative setting, this modality uses intravenous contrast with images acquired in the portal venous phase (Fig. 1). Oral or rectal contrast may also be given but is not required, because the primary lesion frequently is not visualized.
Imaging of distant metastatic disease
The presence of distant metastatic disease at initial presentation affects many treatment decisions. As noted, therapeutic plans change when metastatic disease is identified in patients with nonobstructing primary colorectal cancers. Chemotherapy, rather than surgical resection, may become the first-line treatment of choice. The rationale for this is based on high response rates to current chemotherapeutic regimens [3], the potential of adjuvant treatment to convert unresectable disease to
Imaging of rectal cancers after neoadjuvant chemoradiation
Preoperative examination after completion of neoadjuvant chemoradiation therapy is critical. Physical examination includes assessment of tumor mobility and tumor distance from the upper anal canal, both of which influence surgical planning. Patients with bulky tumors that have responded to therapy may be candidates for low anterior resection. However, tumors showing minimal response to treatment indicate aggressive tumor biology, and fixed tumors may require en bloc resection of surrounding
Postoperative imaging and surveillance
Generally, 30% to 50% of patients have recurrent or metachronous disease after resection of stage II or III colorectal carcinoma. At this time, there is no uniform strategy for following all colorectal cancer patients after surgical resection. A randomized, controlled trial in Spain found that a strategy of intense surveillance, including periodic clinical evaluations, laboratory testing with CEA level, annual colonoscopy, chest x-ray, and abdominal CT scan or ultrasound scan improved survival
Imaging of locally recurrent rectal cancer
Imaging of recurrent rectal cancer is particularly challenging. Appropriate patient selection for surgical treatment is critical, because salvage surgery is associated with significant morbidity and only complete resection is associated with a survival advantage [63]. It is therefore crucial to determine through imaging whether surgery is feasible and which organs adjacent to the recurrent mass must also be resected. Perhaps the most difficult aspect of interpreting imaging studies of recurrent
Summary
With improvements in therapy for colorectal cancer, accurate imaging has taken on an increased significance. Preoperative diagnosis of metastatic disease helps identify patients who could undergo combined resection or might benefit from systemic therapy before surgery. Accurate imaging of rectal cancer is critical in evaluating locally advanced disease treatable by combined modality therapy, including chemoradiation and surgery. Postoperative imaging enhances identification of recurrent disease
References (65)
- et al.
Colorectal cancer
Mayo Clin Proc
(2007) - et al.
The utility of routine preoperative computed tomography scanning in the management of veterans with colon cancer
Am J Surg
(2002) - et al.
Magnetic resonance colonography versus colonoscopy as a diagnostic investigation for colorectal cancer: a meta-analysis
Clin Radiol
(2005) - et al.
Improved survival and local control after total mesorectal excision or D3 lymphadenectomy in the treatment of primary rectal cancer: an international analysis of 1411 patients
Eur J Surg Oncol
(1999) Pelvic radiological imaging: a surgeon's perspective
Eur J Radiol
(2003)- et al.
Imaging for predicting the risk factors—the circumferential resection margin and nodal disease—of local recurrence in rectal cancer: a meta-analysis
Semin Ultrasound CT MR
(2005) - et al.
Preoperative staging of rectal cancer by MRI; results of a UK survey
Clin Radiol
(2005) - et al.
Outcome after simultaneous colorectal and hepatic resection for colorectal cancer with synchronous metastases
Surgery
(2004) - et al.
Assessing the predictive value of clinical complete response to neoadjuvant therapy for rectal cancer: an analysis of 488 patients
J Am Coll Surg
(2002) - et al.
Sequential preoperative fluorodeoxyglucose-positron emission tomography assessment of response to preoperative chemoradiation: a means for determining longterm outcomes of rectal cancer
J Am Coll Surg
(2004)
Restaging after neoadjuvant chemoradiotherapy for rectal adenocarcinoma: role of F18-FDG PET
Biomed Pharmacother
Colon cancer survival rates with the new American Joint Committee on Cancer sixth edition staging
J Natl Cancer Inst
Efficacy of routine preoperative computed tomography scans in colon cancer
Am Surg
Staging of rectal cancer: diagnostic potential of multiplanar reconstructions with MDCT
AJR Am J Roentgenol
Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults
N Engl J Med
Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia
JAMA
Prognostic significance of the circumferential resection margin following total mesorectal excision for rectal cancer
Br J Surg
Diagnostic accuracy of preoperative magnetic resonance imaging in predicting curative resection of rectal cancer: prospective observational study
BMJ
Preoperative versus postoperative chemoradiotherapy for rectal cancer
N Engl J Med
Preoperative irradiation for unresectable rectal and rectosigmoid carcinomas
Cancer
Combined modality therapy of rectal cancer: decreased acute toxicity with the preoperative approach
J Clin Oncol
Preoperative chemotherapy and radiation therapy for locally advanced primary and recurrent rectal carcinoma. A report of surgical morbidity
Cancer
A pathologic complete response of rectal cancer to preoperative combined-modality therapy results in improved oncological outcome compared with those who achieve no downstaging on the basis of preoperative endorectal ultrasonography
Ann Surg Oncol
T-level downstaging and complete pathologic response after preoperative chemoradiation for advanced rectal cancer result in decreased recurrence and improved disease-free survival
Dis Colon Rectum
Adjuvant therapy for patients with colon and rectum cancer
Consens Statement
Long-term oncologic outcome following preoperative combined modality therapy and total mesorectal excision of locally advanced rectal cancer
Ann Surg
Rectal cancer: review with emphasis on MR imaging
Radiology
Accuracy of endorectal ultrasonography in preoperative staging of rectal tumors
Dis Colon Rectum
Rectal tumour staging: MR imaging using pelvic phased-array and endorectal coils vs endoscopic ultrasonography
Eur Radiol
Local staging of rectal cancer with transrectal ultrasound and endorectal magnetic resonance imaging: comparison with histologic findings
Dis Colon Rectum
Cited by (5)
Controversies in radiation for upper rectal cancers
2012, JNCCN Journal of the National Comprehensive Cancer NetworkCurrent concepts and future perspectives on intraoperative fluorescence imaging in cancer: Clinical need
2012, Current Medical Imaging ReviewsDirect tumor invasion in colon cancer: Correlation with tumor spread and survival
2008, Diseases of the Colon and RectumSuccessful rectal cancer local recurrence radiofrequency ablation
2008, Clinical and Translational Oncology