The Relationship of Worst Pattern of Invasion (WPOI) with Clinicopathological Parameters: A Retrospective Cohort Study

: Rationale and objective The worst pattern of invasion (WPOI) has been in the last few years a highly studied pathological parameter. There is a clear trend of non-cohesive WPOI (4-5) to be highly aggressive and to affect outcomes negatively. The aim of this study was to investigate the link between WPOI and other clinicopathological parameters which are the lymph node metastasis (LNM), depth of invasion (DOI) and tumor size (TS). Methods This was a retrospective cohort study. The patients enrolled in the study were diagnosed with oral squamous cell carcinoma (OSCC) and underwent treatment at the Department of Stomatology, Oral and Maxillofacial Surgery at University Hospital Ibn Rochd (CHU 20th August). The exposure variable was the Worst Pattern of Invasion (WPOI) The outcome variables were LNM, DOI and TS. All statistical analysis was conducted using JASP version 0.19.3.0. Results A total of 33 patients were included in the study. The mean age was 65.1 years and the sample showed a clear male predominance. The relationship between WPOI and LNM was examined using a chi-squared test. Among patients with non-cohesive WPOI, 6 out of 13 (46.2%) had LNM, compared to 4 out of 20 (20%) in the cohesive WPOI group. Although the percentage of LNM was higher in the non-cohesive group, this difference was not statistically significant (X2(1)=2.552,p=0.110). An independent samples t-test was performed to assess the relationship between WPOI and DOI. The mean DOI was greater in the non-cohesive group (12.54 mm, SD = 8.09 mm) compared to the cohesive group (8.80 mm, SD = 5.69 mm). This difference, however, was not statistically significant (t(31)=−1.562,p=0.129). The relationship between WPOI and TS was analyzed using an independent samples t-test. Interestingly, the mean TS was larger in the cohesive group (42.60 mm, SD = 26.39 mm) than in the non-cohesive group (32.08 mm, SD = 10.63 mm). This difference was also not statistically significant (t(31)=1.361,p=0.183). Conclusion Although the results weren’t statistically significant, they should be put into the broader context of the study sample size of (n=33). The higher incidence of LNM and higher DOI in the non-cohesive group (types 4-5) is in line with the strong correlation found in the literature. Our results, while not statistically significant, corroborate the established link between non-cohesive WPOI and more aggressive disease.