Polypectomy alone for cure may be used in certain instances in which polyps with invasive cancer can be completely resected with clear margins and have favorable histologic features.[35,36] For patients with advanced cancers of the mid- to upper rectum, LAR followed by the creation of a colorectal anastomosis may be the treatment of choice. However, in general, for locally advanced rectal cancers for which radical resection is indicated, TME with ANP techniques via LAR is preferable to APR.[25,33]
Although postoperative therapy for patients with stage II or III rectal cancer remains an acceptable option, neoadjuvant therapy for rectal cancer, using preoperative chemoradiation, is now the preferred option for patients with stage II and III disease.[Level of evidence: 1iA] Benefits of neoadjuvant chemoradiation include tumor regression, downstaging and improvement in resectability, and a higher rate of sphincter preservation and local control. Complete pathologic response rates of 10% to 25% may be achieved with preoperative chemoradiation therapy.[38,39,40,41,42,43,44,45] However, preoperative radiation therapy is associated with increased complications compared to surgery alone; some patients with cancers at a lower risk of local recurrence might be adequately treated with surgery and adjuvant chemotherapy.[46,47,48,49] (See Treatment Option Overview section for more information.)
The prognosis of patients with rectal cancer is related to several factors, including the following:[7,25,26,29,30,31,32,50,51,52]
- Presence or absence of nodal involvement and the number of positive lymph nodes.[7,29,30,31,32]
- Adherence to or invasion of adjacent organs.
- Presence or absence of distant metastases.[7,26]
- Presence or absence of high-risk pathologic features, including positive surgical margins, lymphovascular invasion, perineural invasion, and poorly differentiated histology.[50,51,53]
- Perforation or obstruction of the bowel.[7,52]
- CRM or depth of penetration of the tumor through the bowel wall.[7,25,54]
However, only disease stage (tumor, nodal, and distant) has been validated in multi-institutional prospective studies.
A large number of studies have evaluated various other clinical, pathologic, and molecular parameters; as yet, none has been validated in multi-institutional prospective trials.[55,56,57,58,59,60,61] For example, MSI-H, also associated with hereditary nonpolyposis rectal cancer, was shown to be associated with improved survival independent of tumor stage in a population-based series of 607 patients with colorectal cancer who were 50 years old or younger at the time of diagnosis. In addition, gene expression profiling has been reported to be useful in predicting the response of rectal adenocarcinomas to preoperative chemoradiation therapy and in determining the prognosis of stage II and III rectal cancer after neoadjuvant 5-fluorouracil-based chemoradiation therapy.[63,64] Racial and ethnic differences in overall survival (OS) after adjuvant therapy for rectal cancer have been observed, with shorter OS for blacks compared to whites; factors contributing to this disparity may include tumor position, type of surgical procedure, and various comorbid conditions.