Dr Goldberg and Dr Bleday have admirably summarized the current literature regarding the diagnosis, evaluation, and treatment of rectal cancer. In broad strokes, I agree with what they say and wish primarily to highlight a few important issues.
In the description of the anatomy, the authors emphasize their preference for the anorectal ring as the anatomic landmark when evaluating the level of the tumor. Yet in other sections of the chapter, the anal verge and the dentate line are mentioned as the distal landmark rather than the anorectal ring. This is consistent with the confusion that exists in colorectal and general surgery and confounds and confuses recommendations made for approaching rectal tumors. I personally prefer the dentate line because it is a clear tissue transition not altered by patient body habitus. Consider, for example, a lesion at 5 cm from the anal verge. Heavyset patients may have a longer distance from the anal verge to the dentate line (4 cm), leaving the lesion quite close to the dentate line (1 cm above). In contrast, the distance from anal verge to the dentate may be very short in thin patients (1 cm), and the lesion may actually reside relatively high in the rectum (4 cm above the dentate line). This variability holds true for the other landmark mentioned, the anorectal ring. The muscular funnel that comprises the anal sphincters may be long in young muscular patients and shorter in others. These variations lead to unclear recommendations as to how to approach lesions at various heights. The literature would benefit from a standardization of landmarks so that authors and clinicians attempting to follow the recommendations in articles could compare outcomes across studies.
I agree with the authors' recommendation for a CT scan of the chest, abdomen, and pelvis in the preoperative evaluation of patients with rectal cancer and would add that a preoperative PET scan adds value when used selectively to assess abnormalities identified on CT scans. This approach is preferred to the routine use of PET scans as it is more cost-effective. It is better than a follow-up CT in 3 months after surgery in that it allows for earlier identification and treatment of metastatic and may obviate the need for surgical intervention.
The 7th edition of the American Joint Committee on Cancer (AJCC) TNM (tumor-node-metastasis) staging system published in 2010 developed new classifications of stages II and III tumors following the recommendations of the Hindgut Taskforce.1,2 As noted by the authors, the tumors are evaluated about depth of tumor invasion (T), nodal involvement (N), and distant metastases (M). Stage 0 tumors are T0 or Tis, N0 and M0. Stage I is T1 or T2, N0, M0. Stage II is T3 or T4, N0, M0. Stage III is Any T stage, N1 or N2, and M0. Stage IV is Any T stage, Any N stage, and M1. Stages II and III can be subdivided and these subdivisions ...