Association of T and N Categories of the American Joint Commission on Cancer, 8th Edition, with Metastasis and Survival in Patients with Orbital Sarcoma

Importance: No previous studies to date have validated the American Joint Committee on Cancer (AJCC) 8th edition of the TNM classification for orbital sarcoma. Objectives: To determine the prognostic performance of the most recent TNM classification for orbital sarcoma and to identify other prognostic factors for local recurrence, lymph node metastasis, distant metastasis, and death due to disease. Design, Setting, and Participants: This single-center retrospective cohort study included 73 consecutive patients treated for orbital sarcoma from March 1, 2003, through June 30, 2018. Data were analyzed from November 1 to December 31, 2018. Main Outcomes and Measures: T and N categories at presentation and disease-related outcomes, including local recurrence, lymph node metastasis, distant metastasis (DM), and death due to disease (DD). Results: The 73 participants included 43 men (59%), and the median age was 21 (range, 0-77) years. The common histologic types were rhabdomyosarcoma (RMS) (35 [48%]), solitary fibrous tumor/hemangiopericytoma (10 [14%]), and Ewing sarcoma (8 [11%]). The most common TNM designations were T2 N0 M0 (26 [36%]) and T4 N0 M0 (24 [33%]). T category was associated with the risk of all disease-related outcomes, including local recurrence (hazard ratio [HR] for T2 vs T4, 0.22 [95% CI, 0.06-0.81]; HR for T3 vs T4, 0.59 [95% CI, 0.13-2.65]; P =.03), lymph node metastasis by the last follow-up (T1, 1 [14%]; T2, 0; T3, 0; T4, 12 [35%]; P =.001), DM (HR for T2 vs T4, 0.29 [95% CI, 0.08-1.07]; P =.04), and DD (HR of T2 vs T4, 0.16 [95% CI, 0.04-0.73]; HR of T3 vs T4, 0.30 [95% CI, 0.04-2.34]; P =.02). Higher risk of DM and higher risk of DD were associated with disease category of at least T3 (HR for DM, 3.24 [95% CI, 0.89-11.72; P =.06]; HR for DD, 6.32 [95% CI, 1.43-27.95; P =.005]), N1 disease (HR for DM, 13.33 [95% CI, 4.07-43.65; P <.001]; HR for DD, 7.07 [95% CI, 2.45-20.44; P <.001]), tumor size larger than 3 cm (HR for DM, 2.72 [95% CI, 0.92-8.05; P =.06]; HR for DD, 5.79 [95% CI, 1.85-18.14; P <.001]), and age of patient with RMS younger than 1 year or 10 years or older (HR for DM, 6.85 [95% CI, 0.83-56.53; P =.04]; HR for DD, 7.03 [95% CI, 0.85-57.83; P =.04]). Higher risk of local recurrence was associated with disease category of at least T3 (HR for<T3 vs≥T3, 0.20 [95% CI, 0.06-0.71]; P <.01) and tumor size greater than 3 cm (HR for ≤3 cm vs >3 cm, 0.27 [95% CI, 0.09-0.77]; P =.009). Higher risk of lymph node metastasis was associated with disease category of at least T3 (odds ratio [OR], 13.33 [95% CI, 1.77-602.30]; P =.004), alveolar RMS (OR, 9.98 [95% CI, 2.13-51.55]; P =.001), and age of patient with RMS younger than 1 year or 10 years or older (OR, 9.20 [95% CI, 1.01-458.29] P =.03). Conclusions and Relevance: In patients with orbital sarcoma, T and N categories at presentation (defined by the AJCC 8th edition classification) correlate with metastasis and survival. These findings appear to support consideration of strict surveillance testing for regional nodal and systemic metastases in patients with orbital sarcoma with disease category of at least T3 and/or N1 disease.