Regional lymph nodes in rectal cancer

Regional lymph nodes are located along the providing vessels of the rectum. The AJCC confines locoregional lymph node involvement to the following lymph nodes:

• sigmoid mesenteric;
• inferior mesenteric;
• superior rectal/hemorrhoidal;
• middle rectal/hemorrhoidal;
• inferior rectal/hemorrhoidal or mesorectal;
• perirectal;
• sacral promontory (Gerota's);
• lateral sacral;
• presacral;
• internal iliac.

Source: [1].

Lymph nodes outside of these areas are considered metastatic disease (M1) (for example, suspicious inguinal lymph nodes if the distal anal sphincter complex is involved) [1].

Coronal and axial drawings show the nodal stations relevant to anal and rectal cancers. Regional nodal stations are shown for anal cancers (blue-green) and rectal cancers (orange). Nodal stations considered metastatic for both anal and rectal cancer are shaded dark gray. Red and blue circles in the axial drawing are external and internal iliac arteries and veins.

Source: [2].

«Pelvic lymph nodes outside of the mesorectum — internal iliac, external iliac, obturator, and common iliac — are termed lateral pelvic lymph nodes (LPLNs). Rectal cancer with involved LPLNs is managed differently in the United States (US) compared to several countries in Asia. In the US, the AJCC defines only the internal iliac lymph nodes as regional, whereas external and common iliac lymph nodes are considered sites of metastatic disease. On the other hand, in Japan, all LPLNs are considered regional and patients are treated with curative intent [3-4]».

Differences in the understanding and management of LPLNs between the East and the West:

LLN = lateral lymph node; nCRT = neoadjuvant chemoradiotherapy; RT = radiotehrapy.

Source: [5]

Bibliographic references:

[1] van Loenhout R, Zijta F, Lahaye M, Beets-Tan R, Smithuis R. The Radiology Assistant: Rectal Cancer - MR staging 2.0 [Internet]. Radiologyassistant.nl. 2015 [cited 2019 May 28]. Available from: http://www.radiologyassistant.nl/en/p56195b237699d/rectal-cancer-mr-staging-20.html#in565b4b37b539c.
[2] Matalon SA, et al. Anorectal Cancer: Critical Anatomic and Staging Distinctions That Affect Use of Radiation Therapy. Radiographics. 2015 Nov-Dec;35(7):2090-107. Available at: https://doi.org/10.1148/rg.2015150037.
[3] Akiyoshi T, et al. Results of a Japanese nationwide multi-institutional study on lateral pelvic lymph node metastasis in low rectal cancer: is it regional or distant disease? Ann Surg. 2012 Jun;255(6):1129-34. Available at: https://doi.org/10.1097/SLA.0b013e3182565d9d.
[4] Yahya JB, et al. Does a fine line exist between regional and metastatic pelvic lymph nodes in rectal cancer-striking discordance between national guidelines and treatment recommendations by US radiation oncologists. J Gastrointest Oncol. 2018 Jun;9(3):441-447. Available at: https://doi.org/10.21037/jgo.2018.02.05.
[5] Radjindrin A, Shanmugam V. Does Lateral Pelvic Lymph node matters in rectal cancer. Glob Surg. 2018;4(4):1-3. Available at: https://doi.org/10.15761/GOS.1000196.