Positive lateral lymph node was the strongest predictor in both survival and local recurrence. Pelvic sidewall dissection may be indicated for patients with T3-T4 lower rectal cancers because of the greater probability of positive lateral lymph nodes.

No abstract

Although pelvic sidewall dissection does not appear to confer overall benefits regarding local recurrence or survival, the effectiveness of pelvic sidewall dissection in specific patient groups remains uncertain. A randomized controlled study is necessary to clarify this issue.

Dendritic cells (DCs) take up tumour-specific antigen and migrate to regional lymph nodes to generate anti-tumour immunity. Although DC infiltration within human tumour tissue has been reported, the subset distribution has not been fully investigated. This study used immunohistochemistry to investigate DC subset distribution in colorectal adenocarcinoma. DCs expressing CD83, which are considered to be mature DCs, were present mainly in the invasive margin of cancer stroma. CD83(+) DCs in the invasive margin formed clusters with lymphocytes, the majority of which were CD45RO(+) T cells. The number of CD4(+) T cells was greater than that of CD8(+) T cells in these DC-lymphocyte clusters. The elongated cytoplasmic processes of CD83(+) DCs engulfed CD4(+) T cells. DCs that express CD1a were located throughout tumour tissue. Although the number of CD1a(+) DCs was almost the same as that of CD83(+) DCs in the invasive margin of cancer stroma, CD1a(+) DCs were mostly scattered and rarely formed clusters with lymphocytes. DCs that expressed both CD1a and CD83 were rare. Moreover, about 20% of lymphocytes in DC-lymphocyte clusters were positive for Ki-67, and CD83(+) DCs were attached to Ki-67(+) cells. CD83(+) DCs were also present in T-cell areas that had a distinctive structure involving the presence of B-cell lymphoid follicles. These results suggest that in the invasive margin of the colorectal cancer stroma, mature CD83(+) DCs form clusters with T cells to promote T-cell activation for the generation of tumour-specific immunity.

The recurrence rate after curative resection for node-negative T1 colorectal cancer was very low. The effectiveness of surveillance to detect recurrence after curative resection for T1 colorectal cancer should be validated in further studies.