. 2019 Jan 1;9(1):1–21.

Table 1.

Clinical implications of perineural invasion (PNI) in several cancers

Cancer type	Percentage of patients with PNI	Effect of survival	Other clinical outcomes	Refs
Pancreatic ductal adenocarcinoma	70.0%-100.0%	Independent prognosis factor of overall survival and disease-free survival, indicating the high recurrence rate, progress, and poor prognosis of tumor.	Closely related to the occurrence of ache.	[2-6]
Pancreatic ductal adenocarcinoma	70.0%-100.0%		An important danger factor for independent survival in addition to AJCC-TNM tumor staging. PNI can be included in patient stratification factors to direct different diagnosis schemes.	[2-6]
Gastric carcinoma	6.8%-75.6%	Independent prognosis factor of overall survival and disease-free survival, and patients with PNI have a poor prognosis. It is also a reference index for postoperative adjuvant treatment.	The 5-year survival of patients with PNI passing through the subserosa tissue or serosa is 50%, obviously lower than 64% of patients with PNI restricted to submucosa or nerves at the muscularis propria.	[7-10]
Biliary tract tumor	56.0%-88.0%	PNI is an independent prognostic factor of overall survival of biliary tract cancer. The 5-year overall survival of patients with PNI is 28%, whereas that of patients without PNI is 74%.	Radical treatment is difficult, the 5-year survival is low, and tumor is likely to relapse.	[11-14]
Biliary tract tumor	56.0%-88.0%	In gall bladder cancer, PNI is related to the high staging and low overall survival.		[11-14]
Prostate cancer	12.4%-83.6%	A meta-analysis involving 13,412 patients showed that the occurrence of PNI is related to the increase in biochemistry recurrence of prostate cancer after radical operation or radiotherapy (rise of specific antigen of prostate) and is the biological prediction factor of poor prognosis.	Related to the partial or general progress of the tumor, being an independent prognosis influence factor.	[15-17]
Prostate cancer	12.4%-83.6%		PNI positive can reduce survival, but the classification of PNI degree by percentages has more precise predictive value than a simple positive or negative dichotomy.	[15-17]
Head and neck cancer	5.2%-90.0%	Poor prognosis factor of oropharynx squamous cell carcinoma tongue; occurrence of PNI indicates the decrease in overall survival and disease-free survival and increase in distant recurrence rate.	Strong predictive factor of lymphatic metastasis.	[18-21]
		Malignant tumor of parotid gland indicates later TNM staging, high-risk pathology.	Causes facial paralysis and ache.
		Low survival of laryngeal cancer patients after surgical treatment.	Causes facial paralysis and ache.
Colorectal cancer	15.7%-38.9%	Predictive factor of death rate increase within 1 year, and patients with PNI have high a postoperative recurrence rate and low survival rate, indicating poor prognosis.	Independent risk factor of recurrence, indicating worse phenotype of tumor.	[22-25]
Colorectal cancer	15.7%-38.9%	The 5-year overall survival and disease-related survival decrease obviously.	PNI state shall be considered in pathological classification of colorectal cancer.	[22-25]
Cervical cancer	8.6%-31.3%	Patients with PNI have short disease-free survival and overall survival, and PNI is a poor prognosis factor of cervical cancer.	More likely to have adverse histopathological characteristics, e.g., increase of tumor, increase in depth of stromal invasion, lymph node invasion, lymphatic vessel invasion, and lymphatic metastasis. It can guide the operation and the postoperative adjuvant treatment.	[26-28]
Cervical cancer	8.6%-31.3%	PNI is an independent prognostic factor of cervical cancer and indicates poor prognosis in early or terminal cervical cancer.		[26-28]