Analysis of Lymph Node Metastatic Pattern according to the Depth of In-Growth in the Muscularis Propria in T2 Rectal Cancer for Lateral Lymph Node Dissection

Abstract

Background/Aims: The biological behavior of rectal cancers that invade the muscularis propria (pT2) has not been well studied. We retrospectively studied the pattern of lymph node metastases in patients with T2 rectal cancer. Methods: We enrolled 88 patients who had undergone curative resection of T2 colorectal cancer through mesorectal excision and lateral pelvic lymph node dissection; we microscopically estimated the maximum depth of muscularis propria invasion and classified the results into 3 groups representing distinct growth patterns. Results: In cases of pT2 colorectal carcinomas, lateral pelvic lymph node metastases depended on the degree of muscularis propria invasion, and the frequency of metastasis increased with the depth of muscularis propria invasion. Lateral pelvic lymph node metastases were not observed when the depth of muscularis propria invasion was less than half of the thickness of the inner circular layer. Conclusions: These findings suggest that lateral pelvic lymph node metastasis of pT2 colorectal cancer depends on the depth of vertical invasion, which is analogous to the findings in pT1 and pT3 cancers. This information will be useful in select cases in which resection of the lateral pelvic lymph node is required for the treatment of rectal cancer invading the muscularis propria (pT2).

Detailed Stratification of TNM Stage III Rectal Cancer Based on the Presence/Absence of Extracapsular Invasion of the Metastatic Lymph Nodes

“…in Japan, lateral lymph node dissection is generally indicated if the lower margin of the primary cancer is located below the peritoneal reflection or anal canal with invasion into the muscularis propria or beyond. 8 there were no cancer cells in the circumferential margin of resection in any of the cases.…”

D3 Lymph Node Dissection Improves Survival Outcomes in Patients With cT2 Colorectal Non-well-differentiated Adenocarcinoma

“…Only 40% of our patients with cT2 CRC were confirmed as pT2 postoperatively, thus, it is still difficult for surgeons to reliably assess degrees of tumor penetration before surgery. Although endoscopic ultrasonography may help in this regard (16,17), the necessity of endoscopic ultrasonography for every patient and its broad clinical acceptance remains to be seen. Another issue is the single-center, retrospective nature of our investigation.…”

Histopathological characteristics of lateral lymph nodes dictate local or distant metastasis and prognosis in low rectal cancer patients

“…The treatment strategy or different concept for lateral lymph nodes may affect the local recurrence and prognosis of RC patients. Recent reports suggested that lateral lymph node dissection decreased the local recurrence and had prognostic benefits 16,17) . However, even in RC patients with lateral lymph node metastasis, some patients had a good prognosis and others had a poorer one.…”