Using feasibility dose-volume histograms to reduce intercampus plan quality variability for head-and-neck cancer.

The purpose of this work is to objectively assess variability of intercampus plan quality for head-and-neck (HN) cancer and to test utility of a priori feasibility dose-volume histograms (FDVHs) as planning dose goals. In this study, 109 plans treated from 2017 to 2019 were selected, with 52 from the main campus and 57 from various regional centers. For each patient, the planning computed tomography images and contours were imported into a commercial program to generate FDVHs with a feasibility value (f-value) ranging from 0.0 to 0.5. For 10 selected organs-at-risk (OARs), we used the Dice similarity coefficient (DSC) to quantify the overlaps between FDVH and clinically achieved DVH of each OAR and determined the f-value associated with the maximum DSC (labeled as f-max). Subsequently, 10 HN plans from the regional centers were replanned with planning dose goals guided by FDVHs. The clinical and feasibility-guided auto-planning (FgAP) plans were evaluated using our institutional criteria. Among plans from the main campus and regional centers, the median f-max values were statistically significantly different (p < 0.05) for all OARs except for the left parotid (p = 0.622), oral cavity (p = 0.057), and mandible (p = 0.237). For the 10 FgAP plans, the median values of f-max were 0.21, compared to 0.37 from the clinical plans. With comparable dose coverage to the tumor volumes, the significant differences (p < 0.05) in the median f-max and corresponding dose reduction (shown in parenthesis) for the spinal cord, larynx, supraglottis, trachea, and esophagus were 0.27 (8.5 Gy), 0.3 (7.6 Gy), 0.19 (5.9 Gy), 0.19 (8.9 Gy), and 0.12 (4.0 Gy), respectively. In conclusion, the FDVH prediction is an objective quality assurance tool to evaluate the intercampus plan variability. This tool can also provide guideline in planning dose goals to further improve plan quality.

Rates of osteoradionecrosis in resected oral cavity cancer reconstructed with free tissue transfer in the intensity-modulated radiotherapy era.

BACKGROUND: Resected oral cavity carcinoma defects are often reconstructed with osteocutaneous or soft-tissue free flaps, but risk of osteoradionecrosis (ORN) is unknown. METHODS: This retrospective study included oral cavity carcinoma treated with free-tissue reconstruction and postoperative IMRT between 2000 and 2019. Risk-regression assessed risk factors for grade ≥2 ORN. RESULTS: One hundred fifty-five patients (51% male, 28% current smokers, mean age 62 ± 11 years) were included. Median follow-up was 32.6 months (range, 1.0-190.6). Thirty-eight (25%) patients had fibular free flap for mandibular reconstruction, whereas 117 (76%) had soft-tissue reconstruction. Grade ≥2 ORN occurred in 14 (9.0%) patients, at a median 9.8 months (range, 2.4-61.5) after IMRT. Post-radiation teeth extraction was significantly associated with ORN. One-year and 10-year ORN rates were 5.2% and 10%, respectively. CONCLUSIONS: ORN risk was comparable between osteocutaneous and soft-tissue reconstruction for resected oral cavity carcinoma. Osteocutaneous flaps can be safely performed with no excess concern for mandibular ORN.

Influence of Treatment Package Time on outcomes in High-Risk Oral Cavity Carcinoma in patients receiving Adjuvant Radiation and Concurrent Systemic Therapy: A Multi-Institutional Oral Cavity Collaborative study.

OBJECTIVES: To explore the influence of treatment package time(TPT) in high-risk oral cavity squamous cell carcinoma(OCSCC) receiving adjuvant radiotherapy with concurrent chemotherapy(CRT). MATERIALS AND METHODS: We queried our multi-institutional OCSCC collaborative database for cases diagnosed between 2005 and 2015 who underwent surgery followed by adjuvant CRT. All patients had high-risk features: extranodal extension(ENE) and/or positive surgical margin(PM). TPT was days between surgery to last radiotherapy fraction. Kaplan-Meier curves, log-rank p-values and multivariate analysis(MVA) were used to investigate the impact of TPT on overall(OS), disease-free(DFS), locoregional failure-free(LRFS) and distant metastases-free(DMFS) survival. RESULTS: We identified 187 cases: median age 58 (range, 24-87 years), males 66%, and ever smokers 69%. ENE and PM were detected in 85% and 32%, and oral tongue and floor of the mouth constituted 49% and 18%, respectively. Median radiotherapy and cisplatin doses received were 66 Gy and 200 mg/m2. Overall, median TPT was 98 (range, 63-162 days). OS was worse for TPT > 90-days (n = 134) than TPT ≤ 90 (n = 53) at two-(65% vs. 71%) and five-years (45% vs. 62%); p = 0.05, with similar results for DFS. No influence on LRFS or DMFS was noted. More lymph nodes(LN) dissected(P = 0.039), T3-4 disease(P = 0.017), and unplanned reoperations(P = 0.037) occurred with TPT > 90-days. On MVA, TPT in 10-day increments was independently detrimental for OS (Hazard Ratio: 1.14; 95 %Confidence Interval [1-1.28]; P = 0.043), perineural invasion, age and positive LN (p < 0.05 for all). CONCLUSION: In one of the largest multi-institutional cohorts, TPT > 90-days predicted worse OS for high-risk OCSCC receiving adjuvant CRT. All efforts are needed to optimize perioperative care and baseline conditions for favorable outcomes.