Zenga J, et al. - Authors assessed the oncologic outcomes of patients with acinic cell carcinoma of the parotid gland and the results of adjuvant therapy for those with close (≤ 1-mm) margins. Adjuvant radiotherapy did not benefit patients with acinic cell carcinoma of the parotid gland whose only histopathologic risk factor was a close (≤ 1 mm) but negative margin. Though rare, the recurrent disease could occur many years following initial treatment. Lifelong clinical surveillance could benefit the patients with acinic cell carcinoma.

Methods

• Experts identified patients treated surgically from January 2000 to December 2014 for acinic cell carcinoma of the parotid gland from an institutional database in a retrospective case series with medical record review at a single academic tertiary referral center.
• They performed all data analysis in September 2017.
• Parotidectomy, with or without adjuvant radiotherapy or chemoradiotherapy, was conducted for all patients.
• Locoregional control was the primary end point.
• Recurrence patterns and survival were included in secondary end points.

Results

• Findings suggested that 45 patients were identified in this case series (23 [51%] female), with a mean (SD) age of 47.1 (19.5) years.
• In surviving patients, the median follow-up was 56.7 months (range, 18.5-204 months).
• Recurrence was seen in 4 patients (9%) (1 local and 3 distant) at a median of 67.3 months (range, 12.7-136 months) after surgery.
• As per data, 13 patients (29%) had at least one high-risk histopathologic factor (advanced T category, nodal disease, lymphovascular or perineural invasion, high-grade, or positive margins).
• Results demonstrated that significantly improved disease-free survival was seen in the remaining 32 patients (71%) without these high-risk factors (hazard ratio, 0.08; 95% CI, 0.01-0.71).
• Researchers noted that, out of patients without high-risk factors, those with close (≤ 1-mm) margins were significantly more likely to receive adjuvant radiotherapy (10 [56%] vs 1 [7%]; difference, 49%; 95% CI, 16%-82%); this was not related to disease control.
• At a median follow-up of 64.3 months (range, 33-204 months) in the 18 patients with close (≤ 1-mm) margins without other high-risk factors (10 with adjuvant radiotherapy and 8 without adjuvant therapy), recurrence was experienced in only one patient (who had received adjuvant radiotherapy) at 136 months after surgery.