Rectal Cancer Surveillance

Post treatment surveillance for patients with rectal cancer is designed to detect treatable local recurrence and distant metastases in asymptomatic patients. As such, surveillance is appropriate for patients who are candidates for surgery and/or other treatment options, such as chemotherapy. Surveillance is typically recommended for 5 years after treatment.[1][2][3] Approximately 80% of recurrences are detected within 3 years and 95% within 5 years of curative-intent rectal resection. Salvage resection of recurrent disease is possible in more than one-third of patients following rectal cancer resection of the primary tumor with median survival of 3–5 years.[2][3][4][5]

The American Society of Colon and Rectal Surgeons (ASCRS) provides clinical practice guidelines for performing surveillance after surgery. Surveillance after curative-intent rectal cancer resection typically includes history with assessment of symptoms, physical examination including digital rectal examination (DRE), carcinoembryonic antigen (CEA) testing, and computed tomography (CT) that may allow detection of recurrence amenable to intervention (Table 1).[6] Note that Table 1 reflects the most current NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines^®),[1] which are based solely on treatment and stage. The ASCRS guidelines (not shown in Table 1) recommend stratifying patients by local recurrence risk and performing additional testing for those patients deemed higher risk.[7]

Table 1. Rectal Cancer Surveillance

CEA, carcinoembryonic antigen; CT, computed tomography; DWI, diffusion weighted imaging; MRI,
magnetic resonance imaging; q, every; T2W, T2 weighted

aPatients with unfavorable pathologic features (e.g., positive margins, lymphovascular invasion, poorly differentiated histology, T2 stage) have a surveillance strategy with more frequent testing analogous to nonoperative surveillance.

bJANUS phase II/III rectal cancer trial, Smith JJ, chair (personal communication 10-16-2022 and verified early 2025) and NCCN Guidelines v2.2025

cEndoscopic ultrasound may replace magnetic resonance imaging as an option after local excision.

dIf pelvic MRI, must follow rectal cancer protocol.

Adapted with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Rectal Cancer V.4.2025. ©2025 National Comprehensive Cancer Network, Inc. All rights reserved. The NCCN Guidelines® and illustrations herein may not be reproduced in any form for any
purpose without the express written permission of NCCN. To view the most recent and complete version of the NCCN Guidelines, go online to NCCN.org. The NCCN Guidelines are a work in progress that may be refinedas often as new significant data becomes available.

As part of the history and physical exam, DRE with an experienced finger has an important role in rectal cancer surveillance because locoregional recurrence is of greater clinical importance for rectal cancer than for colon cancer due to anatomic and biologic differences. DRE allows palpation of a low anastomosis, the sphincter complex and pelvic floor muscles, presacral space, and pelvic side walls; this exam can be done at the same time as rigid or flexible endoscopy.[1] There is limited evidence to support surveillance proctoscopy after radical resection, an exam that has appeared in some of the older NCCN Guidelines^®. Some practices incorporate frequent proctoscopic examinations into the surveillance schedule following low anterior resection or transanal excision because of increased risk for luminal recurrence, especially in cases with close or incomplete margins, or other unfavorable pathologic features.[1][2][3][4][5][8][9][10]

CEA levels and CT are typically obtained for detection of systemic recurrence. Studies that show advantages for colorectal cancer surveillance include CEA measurements in the regimen, although the test has only 65% positive predictive value and 15% of CEA results are falsely elevated in patients without recurrence.[2] Surveillance regimens that show modest survival benefit include both CEA testing and CT.[4] CT may detect early liver and lung metastases, which can allow a better successful resection of these metastases for cure. Liver magnetic resonance imaging (MRI) and positron emission tomography (PET)–CT are not recommended for routine surveillance after rectal resection but may have some value for patients with equivocal CT findings or elevated CEA levels without demonstrable CT abnormalities. The value of circulating tumor DNA levels (ctDNA) as markers for detecting response to neoadjuvant and operative therapy and for surveillance after treatment in operative and nonoperative pathways is currently under investigation.[11]

Colonoscopy is done prior to rectal resection to search for synchronous neoplasms. Colonoscopy should be done every 3–6 months after rectal resection in those unable to have complete preoperative colonoscopy due to rectal luminal narrowing. Most medical organizations and societies, including NCCN and ASCRS, recommend repeat colonoscopy 1 year after resection because most metachronous cancers are found within 2 years; repeat colonoscopy should then be done every 1–5 years depending on surveillance colonoscopy findings. If the first colonoscopy after resection is normal, the next one should be performed in 3 years. If the repeat colonoscopy is normal, surveillance continues every 5 years. If an advanced adenoma is found on surveillance, a repeat colonoscopy in 1 year is warranted.[1][3][4]

Most rectal cancer surveillance studies include patients with stage II/III disease and potentially curative stage IV disease. Because stage I disease is associated with a 5-year survival rate of >90%, several guidelines recommend only endoscopic surveillance without imaging after rectal resection. However, patients with stage I rectal cancer who are treated by local excision have higher risk for endoluminal and mesorectal local recurrence than those treated by rectal resection, especially those with positive margins, lymphovascular invasion, poorly differentiated histology, or T2 disease. For these patients, a surveillance schedule similar to stage II/III patients is performed in many centers.[1][2][3] Recommended surveillance for local recurrence, whether the rectal cancer has good or poor features, is physical exam and proctoscopy is every 3–6 months for the first 2 years. For those with higher risk features, this evaluation is continued every 6 months for a total of 5 years.[1]

Surveillance strategies are modified for patients with genetic cancer syndromes and those who have organ-preserving nonoperative treatment—referred to as “watch and wait” (refer to the chapter on neoadjuvant therapy for more information on the watch-and-wait strategy).[12] Patients with genetic colorectal cancer syndromes such as familial adenomatous polyposis and Lynch syndrome require more frequent endoscopic exams and surveillance of other organs at risk. If not done preoperatively, genetic counseling should be offered to these patients and their high-risk relatives.[1][2][3]

Surveillance after rectal cancer treatment can be costly when considering the marginal survival advantage. Surveillance strategies also need to be balanced with the patient’s treatment preferences and medical status to undergo further chemotherapy or surgery when a recurrence is noted. Cost will need to be assessed in the future with the development of new surveillance methods.[2][3] The cost of frequent nonoperative management testing for patients with a clinical complete response after total neoadjuvant therapy also will need to be compared to the cost of a total mesorectal excision (TME) and its associated complications; quality-of-life considerations in patients with low anterior resection syndrome after TME also will need to be considered. Rectal cancer surveillance guidelines after rectal resection and for nonoperative management may change with evolving evidence-based literature. Therefore, clinical practice guidelines should be consulted regularly for updates.