Table 2.

Summary of study findings

Author, year	Total, n	pT1	pT2	pT3	pT4	Local recurrence in PNI+ patients			Local recurrence in PNI− patients			HR	P‐value
						PNI+ (n)	LR (n)	LR (%)	PNI− (n)	LR (n)	LR (%)
Tai, 2011	307	146	161	—	—	84	16	19.0%	223	30	13.5%	—	0.221
Ganly, 2012	164	76	88	—	—	22b	1	4.5%	124b	13	10.5%	—	0.56
Chen, 2013	442	272	170	—	—	65	12	18.5%c	377	55	14.6%	—	NS
Chatzistefanou, 2014	78	50a		28a		—	—	26.3%d	—	—	27.5%d	—	0.332
Aivazian, 2015	318	108	106	26	76	—	—	—	—	—	—	1.26e	1.00
Matsushita, 2015	89	82a		7a		—	—	23%	—	—	26%	—	NS
Low, 2016	121	121	—	—	—	24	5	20.8%	65	6	9.2%	—	0.33

HR, hazard ratio; LR, local recurrence; n, number; NS, not significant; PNI−, perineural invasion‐negative; PNI+, perineural invasion‐positive.

^aThese numbers represent T1 and T2 or T3 and T4 cases.

^bThere were also a number of patients in which PNI was not reported.

^cPNI and lymphovascular invasion were combined as a high risk group in the calculations of local recurrence.

^dLocal recurrence rates were calculated in patients who did not receive postoperative radiotherapy.

^eHazard ratios were 0.42 (P = 0.247) and 2.24 (P = 0.049) for unifocal and multifocal, respectively.