Abstract: Background and purpose: Histone modification is an important form of epigenetic modification. Aberrant epigenetic modifications can result in a variety of diseases and cancers. Aim of the present study was to investigate the prognostic value of the histone methyltransferase hSETD1A expression in rectal cancer patients. Methods: A total of 141 rectal cancer patients who underwent surgical operation between Jan. 2012 and Dec. 2014 at Fujian Cancer Hospital were enrolled in the study. The expression of hSETD1A was detected by immunohistochemistry in all cancer tissues and 50 adjacent normal mucosa tissue samples. The Kaplan-Meier curves and COX regression models were applied for the evaluation of hSETD1A in predicting the long-term outcomes of the patients. Results: Expression of hSETD1A was significant higher in cancer tissues compared with adjacent mucosa tissues (75.2% vs 26.0%, P<0.001). In addition, the positive rate of hSETD1A expression was related to gender and tumor differentiation grade (both P=0.009). However, it was not related to the variation of age, tumor size, lymph node metastasis, TNM stage, presence of perineural invasion or vascular tumor thrombus and the serum levels of carcinoembryonic antigen (CEA) or CA19-9. Survival analysis revealed patients with positive hSETD1A expression had worse 5-year survival rate than those with negative expression of hSETD1A (64.4% vs 76.5%, P=0.036). Furthermore, COX analysis identified hSETD1A, T and N stages were independent prognostic factors in rectal cancer patients. Conclusion: hSETD1A is highly expressed in rectal cancer, which is proposed as an independent prognostic factor.

Key words: Rectal cancer, Histone methyltransferase, hSETD1A, Immunohistochemistry, Prognosis