Surgery versus surgery and postoperative radiotherapy in squamous cell carcinoma of the buccal mucosa: A comparative study

Background: The efficacy of postoperative radiotherapy for squamous cell carcinoma of the buccal mucosa was evaluated. Methods: One hundred seventy-six patients treated between 1989 and 1993 were analyzed. One hundred fifteen patients were treated with surgery alone (Group 1), and 61 patients were treated with a combination of surgery and postoperative radiotherapy (Group 2). Results: Actuarial 3-year locoregional control in Groups 1 and 2 was 11% and 48% for patients with stage III + IV cancer(P = .001) and 71% and 75% for patients with stage I + II cancer(P = .74), respectively. On multivariate analysis for locoregional failure, surgical margin, bone invasion, high grade, and node involvement were significant factors in Group I, whereas in Group 2 only tumor thickness was a significant factor. For local failure, margin, bone invasion, and stage in Group 1 and tumor thickness in Group 2 appeared as significant factors. For nodal failure, clinical nodal (cl NO vs. N+) stage and grade in Group 1 and pathologic nodal stage (pN0 + 1 vs. pN2) in Group 2 were observed as significant factors. On subset analysis, postoperative radiotherapy was observed to have a significant advantage for surgical margins of 2 mm or less in both early pT (T1 + T2) (P = .019) and late pT (T3 + T4) (P = .016) stages. The local failure rate was higher if the time between surgery and radiotherapy was greater than 30 days. Conclusions: Postoperative radiotherapy was effective in decreasing locoregional failure in patients with close surgical margins, tumor thicker than 10 mm, high-grade turners, positive node, and bone invasion. The effect of interval between surgery and postoperative radiotherapy on local failure was margin-dependent.