Upregulated Polo-Like Kinase 1 Expression Correlates with Inferior Survival Outcomes in Rectal Cancer

Background
Human polo-like kinase 1 (PLK1) expression has been associated with inferior outcomes in colorectal cancer. Our aims were to analyse PLK1 in rectal cancer, and its association with clinicopathological variables, overall survival as well as tumour regression to neoadjuvant treatment.
Methods
PLK1 expression was quantified with immunohistochemistry in the centre and periphery (invasive front) of rectal cancers, as well as in the involved regional lymph nodes from 286 patients. Scores were based on staining intensity and percentage of positive cells, multiplied to give weighted scores from 1–12, dichotomised into low (0–5) or high (6–12).
Results
PLK1 scores in the tumour periphery were significantly different to adjacent normal mucosa. Survival analysis revealed that low PLK1 score in the tumour periphery had a hazard ratio of death of 0.59 in multivariate analysis. Other predictors of survival included age, tumour depth, metastatic status, vascular and perineural invasion and adjuvant chemotherapy. There was no statistically significant correlation between PLK1 score and histological tumour regression in the neoadjuvant cohort.
Conclusion
Low PLK1 score was an independent predictor of superior overall survival, adjusting for multiple clinicopathological variables including treatment.

【背景】人polo样激酶1（polo-like kinase 1, PLK1）的表达与结直肠癌患者的不良预后相关。本研究旨在分析直肠癌组织中PLK1的表达水平，及其与临床病理特征、总生存期以及新辅助治疗后肿瘤退缩程度的关联。
【方法】本研究纳入286例直肠癌患者，采用免疫组织化学（immunohistochemistry）法检测直肠癌组织中心区、外周（侵袭前沿）以及受累区域淋巴结中的PLK1表达水平。评分基于染色强度与阳性细胞占比的乘积，得到1~12分的加权评分，并将其划分为低表达组（0~5分）与高表达组（6~12分）。
【结果】肿瘤外周区域的PLK1评分与相邻正常黏膜存在显著差异。生存分析结果显示，在多变量分析中，肿瘤外周区域PLK1低表达组的死亡风险比为0.59。其他影响总生存期的预测因素包括年龄、肿瘤浸润深度、转移状态、血管及神经侵犯与辅助化疗。在新辅助治疗队列中，PLK1评分与肿瘤组织学退缩程度未发现具有统计学意义的相关性。
【结论】在校正包括治疗方式在内的多项临床病理变量后，PLK1低表达是总生存期更优的独立预测因素。