Oncologic significance of the lateral margin in buccal cancer.

Objective: To evaluate the specific oncologic significance of the lateral margin (LM)- the marginal plane closest to skin- in resected buccal cancer.

Materials And Methods: 216 consecutive, treatment naïve patients undergoing primary surgery for buccal cancer were included. Cheek skin was resected based on clinical features of skin or subcutaneous involvement or proximity to oral commissure. Main outcomes were 1) frequency of LM ≤1 mm in relation to other (anterior, posterior, superior and inferior) margins and 2) association of LM ≤1 mm with LRFS and DFS. Secondary outcomes were rate of LM ≤1 mm and size of LM with and without skin resection.

Results: A total of 67 (31 %) patients had one or more margin ≤1 mm, of which LM comprised 36 (54 %). LM ≤1 mm was disproportionately highest among the five marginal planes (p < 0.001) and was independently associated with LRFS and DFS. Both associations held in sensitivity analysis wherein patients with co-existent margin ≤1 mm at any of the other four marginal planes underwent group-wise exclusion. Skin resection and preservation was performed in 61 (28 %) and 155 (72 %) patients respectively. The latter had a higher rate of LM ≤1 mm and smaller LM size (both p < 0.05).

Conclusions: This cohort study of buccal cancer shows that LM is most prone for ≤1 mm size. LM ≤1 mm predicts worse LRFS and DFS independent of other margins and risk factors. As skin preservation is associated with a higher rate of LM ≤1 mm, surgeons must lower the threshold to encompass more tissue laterally, including skin where appropriate.