Written by Elise Lawson, MD, MSHS
Management of rectal cancer advanced significantly in the past two decades, resulting in decreased rates of cancer recurrence and improved survival. Advances include better imaging modalities for tumor localization and staging, introduction of neoadjuvant (before surgery) radiation and chemotherapy, and a greater focus on surgical technique for adequate resection. Five-year survival approaches 75% for rectal cancer patients that receive guideline-recommended care but is considerably less for patients not receiving that standard.
Presentation and Staging
Patients with rectal cancer often present initially with symptoms including bleeding, rectal pain and tenesmus or cramping. Patients may also notice narrowed-caliber stool or a sensation of incomplete evacuation of their bowels, which they frequently describe as “constipation.” Others will be asymptomatic and diagnosed on a screening colonoscopy. Finally, a smaller group of patients will present initially with obstruction, requiring urgent intervention.
After a patient is diagnosed with biopsy-proven adenocarcinoma of the rectum, it is critical that they undergo accurate staging with laboratory and radiologic studies prior to initiating treatment:
- Laboratory examinations – Along with routine lab tests (complete blood count, chemistry panel, liver function tests), it is recommended that carcinoembryonic antigen (CEA) levels be assessed for all patients prior to initiating treatment in order to establish a baseline. CEA levels can then be followed post-treatment as part of active surveillance for rectal cancer recurrence.
- Magnetic Resonance Imaging (MRI) – Dedicated high resolution MRI with a specific rectal cancer protocol is increasingly being used to assess for local tumor advancement and lymph node involvement. Such protocols have improved the accuracy of pre-treatment clinical staging, leading to better informed decision-making for neoadjuvant (before surgery) radiation and chemotherapy as well as surgical planning. However, it is important to note that standard pelvic MRI may not be sufficient or provide as accurate information for rectal cancer staging. Thus, patients should be sent to imaging facilities that have implemented a specific rectal cancer protocol for performing high resolution pelvic MRI.
- Endorectal Ultrasound (EUS) – EUS (also called transrectal ultrasound – TRUS), has a complementary role to an MRI in the staging of rectal cancer. Not every patient needs an EUS, however, this imaging modality can be helpful for distinguishing between T1 and T2 tumors, which may help guide decision-making regarding local excision versus radical surgery.
- Computed Tomography (CT) Scan – CT scan of the chest and abdomen is recommended to assess for metastatic disease as the lungs and liver are the most frequent sites of distant spread for rectal cancer. A chest x-ray is no longer considered sufficient to assess for pulmonary metastases. CT scan of the pelvis is also not necessary if a pelvic MRI is performed.
Patients with low-risk early stage rectal cancer may undergo surgery alone as definitive treatment. However, patients with locally advanced (stage II or III) disease benefit from multimodality treatment with radiation and/or chemotherapy prior to surgical intervention. Patients with metastatic disease at the time of diagnosis (stage IV) may still be candidates for curative surgical resection depending upon the pattern and extent of spread of the cancer and response to preoperative chemotherapy.
- Radiation – The addition of radiation to surgery significantly decreases recurrence rates for locally advanced rectal cancer (stage II or III). Further, radiation given before surgery is more effective and less toxic than radiation given after surgery. Radiation facilities are located throughout Wisconsin, thus treatment can usually be administered close to where patients live.
- Chemotherapy – Chemotherapy is recommended for patients with stage III or high-risk stage II rectal cancer and traditionally was offered in the postoperative setting. However, a significant percentage of patients do not go on to receive chemotherapy after surgery, despite an overall survival benefit of this treatment. To optimize outcomes for patients, chemotherapy is now being moved to the neoadjuvant (preoperative) setting.
- Local Excision – There are different options for surgical resection of rectal cancer, depending on the location and stage of disease. Local excision is an appropriate surgical option for patients with T1 tumors that do not have high-risk pathologic features. Patients undergoing local excision as definitive treatment of rectal cancer must be very carefully selected and determined to be low-risk for lymph node involvement as this treatment does not excise or treat the mesorectal lymph nodes.
- Radical Excision – Appropriate surgical technique is essential to optimizing oncologic and functional outcomes for patients with rectal cancer. Whether the patient undergoes abdominoperineal resection (APR) with permanent colostomy versus low anterior resection (LAR) with restoration of bowel continuity depends upon how low the tumor is and whether or not it involves the sphincter muscle. Studies have shown that surgeons with specialty training are more likely to perform sphincter-preserving procedures thus avoiding permanent ostomies for more patients.
A critical component of both APR and LAR is sharp total mesorectal excision (TME), in which the mesentery adjacent to the rectum containing the draining lymph nodes is taken as a complete, undisrupted packet along with the rectum. The quality of the pathology specimen and status of the distal and circumferential margins are closely associated with cancer recurrence, emphasizing the importance of precise dissection by an experienced surgeon.
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Given the complexity of rectal cancer management, decisions regarding individual treatment plans are best made collaboratively by a multidisciplinary team involving medical and radiation oncologists, radiologists and surgeons with rectal cancer expertise. It is also preferable for patients with potentially resectable cancer to be evaluated by a colorectal surgeon prior to initiating treatment. At UW Health, we have a multidisciplinary team of physicians that meets weekly to discuss treatment planning for all patients with rectal cancer. For questions or to refer a patient, please call the UW Health Colorectal Surgery Clinic at the Digestive Health Center.
UW Health Digestive Health Center
Colorectal Surgery Clinic