목적: Worst pattern of invasion-5 (WPOI-5) has been identified as a negative survival prognosticator of oral tongue squamous cell carcinoma (OTSCC). However, it has not been utilized for treatment decision in clinical practice. The study aimed to evaluate the prognostic value of WPOI-5 for patients with pathologically early- stage and low-risk OTSCC. 방법:Those with pathologically early-stage and low-risk OTSCC who received radical surgery without adjuvant therapy (n=224) between 2005 and 2016 were analyzed. The low-risk group was defined as patients without the existence of any of the following pathological adverse features, including perineural invasion, lymphovascular invasion, poorly differentiated histology, lymph node metastasis, and close (<5mm) or positive surgical margin. WPOI-5 was defined as tumor satellites greater or equal to 1 mm distance from main tumor or next closest satellite. The prognostic value of WPOI-5 on cancer specific survival (CSS) and locoregional recurrence free survival (LRRFS) was analyzed and a WPOI-5-based nomogram was generated for further validation. 결과:The 5-year CSS and LRRFS rates were 95% and 91.9%, respectively. For those with WPOI-5, the 5-year CSS and LRRFS were significantly inferior to those without WPOI-5 (both p<0.001). In multivariate Cox model, WPOI-5 was observed to be an unfavorable prognosticator of 5-year CSS (HR: 6.908, 95% CI: 1.738-27.462, p=0.006) and LRRFS (HR: 14.91, 95% CI:5.052-44.003, p<0.001). The value of area under curves of the nomogram for 5-year LRRFS increases from 0.789 to 0.842 after adding the variable of WPOI-5 into the assorted clinicopathological factors. 결론:Presence of WPOI-5 is a potentially risk factor for patients with pathologically early-stage and low-risk OTSCC, which might highlight the importance of clinical trial to investigate the role of adjuvant therapy for these patients.