Interleukin-24 is correlated with differentiation and lymph node numbers in rectal cancer

Abstract

Aim: To assess the significance of interleukin (IL)-24 and vascular endothelial growth factor (VEGF) expression in lymph-node-positive rectal cancer.

Methods: Between 1998 and 2005, 90 rectal adenocarcinoma patients with lymph node involvement were enrolled. All patients received radical surgery and postoperative pelvic chemoradiotherapy of 50.4-54.0 Gy. Chemotherapy of 5-fluorouracil and leucovorin or levamisole was given intravenously during the first and last week of radiotherapy, and then monthly for about 6 mo. Expression of IL-24 and VEGF was evaluated by immunohistochemical staining of surgical specimens, and their relations with patient characteristics and survival were analyzed. The median follow-up of surviving patients was 73 mo (range: 52-122 mo).

Results: IL-24 expression was found in 81 out of 90 patients; 31 showed weak intensity and 50 showed strong intensity. VEGF expression was found in 64 out of 90 patients. Negative and weak intensities of IL-24 expression were classified as negative expression for analysis. IL-24 expression was significantly reduced in poorly differentiated tumors in comparison with well or moderately differentiated tumors (P = 0.004), N2b to earlier N stages (P = 0.016), and stage IIIc to stage IIIa or IIIb (P = 0.028). The number of involved lymph nodes was also significantly reduced in IL-24-positive patients in comparison with IL-24-negative ones.There was no correlation between VEGF expression and patient characteristics. Expression of IL-24 and VEGF was not correlated with survival, but N stage and stages were significantly correlated with survival.

Conclusion: IL-24 expression was significantly correlated with histological differentiation, and inversely correlated with the degree of lymph node involvement in stage III rectal cancer.

Keywords: Histological differentiation; Interleukin-24; Lymph node; Rectal cancer; Vascular endothelial growth factor.

Figure 1

Immunohistochemical staining of interleukin-24 in rectal tissue (200 ×). A: In the normal rectal mucosa tissue, the non-neoplastic glandular epithelial cells were strongly positive for IL-24; B: In rectal cancer, a well-differentiated adenocarcinoma showed strong positive expression of IL-24; C: A moderately differentiated adenocarcinoma showed weak positive expression of IL-24; D: A poorly differentiated adenocarcinoma showed negative expression of IL-24. IL-24: Interleukin-24.

Figure 2

The number of involved lymph nodes according to interleukin-24 intensity (A) and expression status (B) in node-positive rectal cancer patients. 1Negative (n = 9) and weak (n = 31) intensities were classified as negative expression, and strong intensity (n = 50) as positive. IL: Interleukin.