目標：大腸直腸癌（CRC）在惡性腫瘤中具高發生率與死亡率，台灣CRC病患急劇增加可能與環境汙染物（多環芳香烴碳氫類化合物、硝酸鹽和亞硝酸鹽類）有關。因此，本篇研究探討此類汙染物與台灣CRC的相關性。方法：配對的CRC患者血漿與腫瘤組織檢體取自高雄長庚紀念醫院組織銀行，由正修科技大學超微量研究科技中心萃取後，以酵素免疫分析法測定其中之硝酸鹽及亞硝酸鹽濃度，另以氣相層析儀串聯質譜儀進行16種多環芳香烴偵測。結果：因血漿中所含之亞硝酸鹽及多環芳香烴均未檢出，後續實驗針對硝酸鹽進一步分析。實驗結果顯示CRC病患血漿的硝酸鹽濃度與對照組無顯著差別，但腫瘤組織中的硝酸鹽含量顯著高於配對的血漿。但是，硝酸鹽濃度在配對的CRC血漿與腫瘤組織中不具顯著關聯，且不同期別CRC的血漿與腫瘤組織硝酸鹽含量也無顯著差異。結論：此較小樣本數之前驅性研究顯示血液與腫瘤中硝酸鹽含量與CRC的相關性並不顯著，但是可提供後續進一步研究的重要潛在參考依據。

Objectives: Colorectal cancer (CRC) is a major health problem with high incidence and mortality rates worldwide. The increased incidence of CRC in Taiwan may be associated with environmental contaminants such as polycyclic aromatic hydrocarbons (PAHs), nitrate, and nitrite. Accordingly, in this study, the relationship between these contaminants and CRC was investigated. Methods: Paired plasma and tumor tissues of CRC patients were obtained from the Tissue Bank at Kaohsiung Chang Gung Memorial Hospital. The samples were extracted and analyzed using enzyme-linked immunosorbent assay and gas chromatography-tandem mass spectrometry for detecting the concentrations of nitrate/nitrite and 16 types of PAHs, respectively, at the Super Micro Mass Research & Technology Center, Cheng Shiu University. Results: Nitrite and the 16 types of PAHs were undetectable in the plasma; thus, only nitrate was selected for further investigation. The data indicated that the plasma levels of nitrate were not significantly different between the CRC and control groups. Notably, the average levels of nitrate in tumor tissues were significantly higher than the average plasma levels, but the nitrate levels in paired plasma and tumor tissues did not show a significant correlation. Moreover, no significant difference in the nitrate levels of plasma and tumor tissues was found in patients with different tumor stages. Conclusions: In this pilot study, no significant correlation was found between the nitrate levels in plasma and tumors of CRC patients, which could be caused by the smaller study cohort. However, the result is a potentially valuable reference for further research.