Study: Positive Margins Do Not Impact Survival Outcomes in Tracheal Adenoid Cystic Carcinoma Resection

Even if negative margins cannot be achieved in patients with adenoid cystic carcinoma (ACC) of the trachea, outcomes may not differ, with or without adjuvant radiation, according to recent research.

“Performing a complete resection of tracheal adenoid cystic carcinoma and achieving negative surgical margins can be difficult,” said study author Chi-fu Jeffrey Yang, MD, of Duke University Medical Center in Durham, N.C., in a presentation. “Patients are often not diagnosed until they develop relatively bulky, locally advanced tumors, because their only symptoms are uncommon.”

Yang presented the study’s findings at the 65^th Annual Meeting & Exhibition of the Southern Thoracic Surgeons Association.

“Aggressively chasing negative microscopic margins can lead to excessive longitudinal tracheal resection that could preclude safe reconstruction,” Yang said.

Yang noted that the impact of microscopic positive margins on long-term outcomes has not been well characterized. Long-term local control has been reported after resection, even with positive surgical margins. Radiation has tended to be recommended to be given after resection for adenoid cystic carcinoma; however, evidence supporting the benefit of postoperative radiation for adenoid cystic carcinoma in terms of either local control or long-term survival is scant.

“There is limited literature regarding the management of tracheal adenoid cystic carcinoma, probably because it is a rare tumor and because there are few centers that regularly perform tracheal resections,” Yang noted.

Yang and his team therefore sought to find evidence supporting treatment strategies for tracheal ACC. They hypothesized that positive margins following ACC resection would be associated with worse survival and that postoperative adjuvant radiation would improve survival rates. They used the National Cancer Data Base to collect information on tracheal ACC resection patients from 1998 through 2015 whose margin status they could determine. Patients were excluded if they had nodal or distant disease. Eligible patients were evaluated using Kaplan-Meier and Cox proportional hazard analysis.

According to the abstract, 152 patients met inclusion criteria, of which 87 (57%) had postresection positive margins. Characteristics including age, female sex, race, tumor size, and year of diagnosis did not differ greatly between the groups, Yang said. Negative margin patients had lower T status at baseline than positive margin patients (T1, 35.1% vs 12.3%; T2, 40.5% vs 35.1%; T3, 10.8% vs 15.8%; T4, 13.5% vs 30.3%). Negative margin patients were also less likely to undergo adjuvant radiation therapy (62.3% vs 78.5%, P = 0.04).

Adjuvant radiation was administered to 105 (69%) of the total cohort and 66 (76%) of the positive margin patients, according to the study abstract. Patients with elevated T status were more likely to have positive margins (T4 compared to T1 adjusted odds ratio [OR], 6.31; 95% CI: 1.76-22.67; P = 0.005). Patients with positive margins and negative margins did not have significantly different five-year survival rates (80% [95% CI: 69-87] vs 84% [95% CI: 70-91], P = 0.49), even after multivariable adjustment (hazard ratio [HR], 2.24; 95% CI: 0.84-6.02; P = 0.11). Analysis of the positive margin group showed no significant difference in five-year survival between patients who received postoperative adjuvant radiation therapy and those who did not (80% [95% CI: 67-88] vs 80% [95% CI: 55-92], P = 0.71), even after multivariable adjustment (HR, 0.54; 95% CI: 0.13-2.18; P = 0.39).

Perioperative outcomes differed slightly between the positive margins and negative margins groups, Yang said, with the exception of hospital stay, which was seven days for both cohorts. Positive margins patients had higher 30-day and 90-day mortality rates (30-day, 2.5% vs 0.0%; P = 0.24; 90-day, 6.3% vs 0.0%; P = 0.11). However, 30-day readmission rates were lower in the positive margins group (1.3% vs 3.8%, P = 0.40).

The study authors concluded in their abstract that while adjuvant radiation therapy is often used in patients with positive margins, it does not benefit survival rates.