Radiation Reduces Recurrence in Positive Margins in Salivary Gland Carcinoma

“In isolation from other possible risk factors for local recurrence, select patients with close surgical margins [of 1 mm or lower] may be considered for observation, as avoidance of postoperative [radiotherapy] for this indication appears likely to be oncologically safe," according to the study authors.

Administering radiation to patients with low- to intermediate-grade major salivary gland carcinomas and positive margins following surgery decreased the risk of disease recurrence, according to findings from a retrospective cohort study published in JAMA Otolaryngology Head & Neck Surgery.

Local and regional recurrence occurred in 4% and 2% of patients, respectively, and 3% had distant metastatic disease following radiotherapy. With respect to any recurrence-free survival (RFS) rates, there were no significant differences between those with submandibular (5%) or parotid (7%) histology (HR, 0.76; 95% CI, 0.24-2.42) and in those with intermediate-grade disease (3%) compared with those who had low-grade disease (7%; HR, 0.48; 95% CI, 0.17-1.33).

Factors that correlated with a local recurrence risk included intraoperative tumor spillage (HR, 3.53; 95% CI, 1.22-10.25), positive margins (HR, 2.86; 95% CI, 1.46-5.58), and postoperative radiation per bivariate analysis (HR, 0.24; 95% CI, 0.09-0.62). Multivariate analysis also highlighted that age at diagnosis (HR, 1.33; 95% CI, 1.06-1.67), positive vs negative margins (HR, 5.21; 95% CI, 2.58-10.54), and postoperative radiation (HR, 0.10; 95% CI, 0.04-0.29) independently correlated with local recurrence.

Investigators highlighted a higher local recurrence risk in patients with positive margins—R1 or R2 margins—compared with those who had R0 margins (HR, 2.47; 95% CI, 1.26-4.82). The local recurrence rate for those with R0 margins was 2% in patients who received radiotherapy compared with 3% in those who received observation (HR, 0.39; 95% CI, 0.12-1.34). Additionally, the local recurrence rate for patients with R1 or R2 margins was 2% in those who underwent radiotherapy vs 20% in those who did not receive radiation (HR, 0.05; 95% CI, 0.01-0.24).

“Patients with positive margins who underwent postoperative [radiotherapy] had lower local recurrence compared [with] patients who did not undergo [radiotherapy],” the study authors wrote. “In isolation from other possible risk factors for local recurrence, select patients with close surgical margins [of 1 mm or lower] may be considered for observation, as avoidance of postoperative [radiotherapy] for this indication appears likely to be oncologically safe.”

This retrospective study was conducted by the American Head and Neck Society Salivary Gland Section between 2010 and 2019 across 41 centers. Investigators aimed to characterize the risk factors related to local recurrence in patients with low- to intermediate-grade salivary gland cancers. Additionally, the study evaluated how margin status and radiotherapy correlated with local RFS, any RFS, disease-specific survival (DFS), and overall survival (OS).

Patients with parotid or submandibular gland resections for low- to intermediate-grade salivary gland carcinomas between January 2010 and December 2019 who also received postoperative radiation with or without chemotherapy or observation were included in the study. Patients 17 years or younger with lymph node metastases, distant metastases at presentation, or prior head and neck radiotherapy or ipsilateral salivary gland surgical resection were excluded from the study.

The study sample included 865 patients, most of whom were female (64%), never smokers (65%), and had parotid tumors (93%). Additionally, most patients had R0 margins (78%), close margins of 1 mm or less (59%), no intraoperative tumor spillage (68%), and tumors that were in direct contact with facial nerves (39%).

At 5 years, the DSS and OS rates across the entire patient population were 98% and 94%. DSS and OS rates were comparable between those with parotid and submandibular sites, and investigators identified no significant differences in outcomes when stratifying patients based on margin status.

The local recurrence rate in patients with close margins was 2% among those who received postoperative radiotherapy compared with 4% in those who did not (HR, 0.38; 95% CI, 0.08-1.70). The local RFS rates across the entire population were 97% at 2 years, 96% at 3 years, 95% at 5 years, and 91% at 10 years, respectively. The corresponding rates for patients with close margins were 98%, 97%, 95%, and 91%, respectively.

Reference

Sajisevi M, Nguyen K, Callas P, et al. Oncologic safety of close margins in patients with low- to intermediate-grade major salivary gland carcinoma. JAMA Otolaryngol Head Neck Surg. Published online December 14, 2023. doi:10.1001/jamaoto.2023.3952