Evaluation of the Impact of Intratumoral Heterogeneity of Esophageal Cancer on Pathological Diagnosis and P16 Methylation and the Representativity of Endoscopic Biopsy

Somatic CDKN2A copy number variations are associated with the prognosis of esophageal squamous cell dysplasia

BACKGROUND

Somatic copy number variations (SCNVs) in the CDKN2A gene are among the most frequent events in the dysplasia-carcinoma sequence of esophageal squamous cell carcinoma. However, whether CDKN2A SCNVs are useful biomarkers for the risk stratification and management of patients with esophageal squamous cell dysplasia (ESCdys) is unknown. This study aimed to investigate the characteristics and prognostic value of CDKN2A SCNVs in patients with mild or moderate (m/M) ESCdys.

METHODS

This study conducted a prospective multicenter study of 205 patients with a baseline diagnosis of m/M ESCdys in five high-risk regions of China (Ci County, Hebei Province; Yanting, Sichuan Province; Linzhou, Henan Province; Yangzhong, Jiangsu Province; and Feicheng, Shandong Province) from 2005 to 2019. Genomic DNA was extracted from paraffin biopsy samples and paired peripheral white blood cells from patients, and a quantitative polymerase chain reaction assay, P16-Light, was used to detect CDKN2A copy number. The cumulative regression and progression rates of ESCdys were evaluated using competing risk models.

RESULTS

A total of 205 patients with baseline m/M ESCdys were enrolled. The proportion of ESCdys regression was significantly lower in the CDKN2A deletion cohort than in the diploid and amplification cohorts (18.8% [13/69] vs. 35.0% [28/80] vs. 51.8% [29/56], P  <0.001). In the univariable competing risk analysis, the cumulative regression rate was statistically significantly lower ( P = 0.008), while the cumulative progression rate was higher ( P = 0.017) in ESCdys patients with CDKN2A deletion than in those without CDKN2A deletion. CDKN2A deletion was also an independent predictor of prognosis in ESCdys ( P = 0.004) in the multivariable analysis.

CONCLUSION

The results indicated that CDKN2A SCNVs are associated with the prognosis of ESCdys and may serve as potential biomarkers for risk stratification.

Feasibility of using P16 methylation as a cytologic marker for esophageal squamous cell carcinoma screening: A pilot study

BACKGROUND

Early diagnosis and treatment of esophageal squamous cell dysplasia (ESCdys) and esophageal squamous cell carcinoma (ESCC) could significantly reduce the incidence and mortality of ESCC. This pilot study aimed to investigate whether P16/CDKN2A methylation could serve as a cytologic biomarker for early detection of ESCdys and ESCC.

METHODS

Paired esophageal biopsy and cytology specimens (exfoliated cells) were obtained from subjects at different stages of ESCC development. The methylation status of P16 gene in these two specimen types was determined using a 115-bp MethyLight assay. Categorical data were compared by the Chi-square test. Logistic regression was performed to assess adjusted odds ratios of P16 methylation associated with ESCC and ESCdys. Prediction models for identifying individuals at risk of ESCC and high-grade ESCdys (high-grade intraepithelial neoplasia, HGIN) were developed by multivariable logistic regression. Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis. Internal validation of the prediction models was performed using the 1000-bootstrap resample.

RESULTS

A total of 105 subjects with diagnoses ranging from normal mucosa through ESCC were included in this study. An increase in P16 methylation frequency was observed with increasing severity of esophageal lesions (p for trend <0.001). In the adjusted logistic regression models, P16 methylation in cytology specimens was positively associated with ESCC and ESCdys risk, whereas P16 methylation in biopsy specimens was only associated with a higher risk of developing ESCC. The predictive capacity of base model I (AUC, 0.816) for ESCC and HGIN was significantly increased by adding P16 methylation in cytology specimens (model III; AUC, 0.882; p = 0.043), but not P16 methylation in biopsy specimens (model II; AUC, 0.850; p = 0.225). Bootstrap validation showed optimism-corrected AUC of 0.789 for model I, 0.822 for model II, and 0.854 for model III.

CONCLUSION

P16 methylation as a cytologic marker was associated with the ESCC development and has the potential for application in minimally invasive ESCC screening.