Head and Neck Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_27_2467 - Scar Bolus Omission During Adjuvant Intensity Modulated Radiation Therapy (IMRT) Does Not Increase Risk of Incisional Recurrence for Oral Cavity Cancers

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Scar Bolus Omission During Adjuvant Intensity Modulated Radiation Therapy (IMRT) Does Not Increase Risk of Incisional Recurrence for Oral Cavity Cancers
C. Hogue, M. J. Fidler, J. Showel, S. Al-Khudari, K. M. Stenson, and N. Sen; Rush University Medical Center, Chicago, IL

Purpose/Objective(s): Locoregionally advanced oral cavity cancers have an increased risk of locoregional recurrence despite multimodality therapy. In an effort to decrease scar recurrences in the post-operative setting, bolus has historically been used to increase the dose to the neck scar in intermediate and high-risk contexts. Since transitioning to IMRT for most post-operative oral cavity cases, we have routinely omitted bolus placement on the neck scar. Here we examine rates of scar recurrences using this approach.

Materials/Methods: This is an IRB approved retrospective study. Patients with intermediate or high risk squamous cell carcinoma of the oral cavity treated with post-operative IMRT were identified from an institutional database. Patients were treated using tomotherapy based IMRT. Demographics, clinical/pathologic parameters, dosimetric data, and cancer-related outcomes were recorded and analyzed. Statistical software was used to determine Kaplan Meier estimates for disease control and survival.

Results: 28 pts met inclusion criteria for this analysis and were treated from 2009 to 2017. Median age was 56 years old (range 35-75); 59% were male. All patients underwent complete resection of the primary tumor with selective neck dissection. Subsites included 11 floor of mouth (40%), 6 oral tongue (21%), 5 buccal mucosa (18%), 3 lower lip (11%), 2 hard palate (7%), and 1 retromolar trigone (4%). 71% were pathologically node positive; 36% had extracapsular extension (ECE). Concurrent chemotherapy was used in 53% of patients. 24 patients (86%) were treated using SIB technique. The post-operative neck was irradiated in all cases. Median dose to the highest risk volume was 6000 cGy (range 5800-6600 cGy). Median treatment package time was 95 days (range 76-137 days). Median follow up for surviving patients after treatment was 21 months (range 3-93 months). One patient experienced a local recurrence at 2 months. Four patients developed distant metastatic progression at a median of 3 months (range 1-16 months). No patients have experienced a regional nodal relapse and there have been no scar recurrences. 3-year actuarial estimates for DFS and OS are 74.7% and 87.4%.

Conclusion: Scar recurrences after post-operative IMRT are rare. Bolus omission has not compromised disease control along the scar.

Author Disclosure: C. Hogue: None. M. Fidler: None. S. Al-Khudari: None. K.M. Stenson: None. N. Sen: None.

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