Patterns and Trends in Adjuvant Therapy for Major Salivary Gland Cancer

Abstract

ObjectiveTo investigate adjuvant therapy indications, utilization, and associated survival disparities in major salivary gland cancer (MSGC).Study DesignRetrospective cohort study.SettingThe 2006 to 2017 National Cancer Database.MethodsPatients with surgically resected MSGC were included (N = 11,398). pT3‐4 classification, pN2‐3 classification, lymphovascular invasion, pathologic extranodal extension (pENE), and positive surgical margin (PSM) were considered indications for adjuvant radiotherapy (aRT). pENE and PSM were considered possible indications for adjuvant chemotherapy. Multivariable logistic and Cox regression models were implemented.ResultsAmong 6694 patients with 1 indication for aRT, 1906 (28.5%) received no further treatment and missed aRT. Age, race, comorbidity status, facility type, and distance to reporting facility were associated with missed aRT (P < .025). Among 4003 patients with ≥1 possible indication for adjuvant chemoradiotherapy (aCRT), 914 (22.8%) received aCRT. Patients with pENE only (38.5%) and both pENE and PSM (44.0%) received aCRT more frequently than those with PSM only (17.0%) (P < .001). Academic facility was associated with aCRT utilization (P < .05). aCRT utilization increased between 2006 and 2017 in both academic (14.8% vs 23.9%) and nonacademic (8.8% vs 13.5%) facilities (P < .05). Among 2691 patients with ≥1 indication for aRT alone, missed aRT portended poorer OS (hazard ratio [HR]: 1.61, 95% confidence interval [CI]: 1.28‐2.03, P < .001). Among 4003 patients with ≥1 possible indication for aCRT, aRT alone (HR: 1.02, 95% CI: 0.89‐1.18, P = .780) and aCRT were associated with similar OS.ConclusionMissed aRT in MSGC occurs frequently and portends poorer OS. Further studies clarifying indications for aCRT are required.

Chemoradiotherapy versus radiotherapy in high risk salivary gland cancer

“…High-risk factors encompassed in this study were delineated as follows: pT3/4 classification, presence of LN metastasis, high histologic grade (Fig. 2 ), PNI, LVI, ENE, and positive margin, consistent with established literature [ 7 , 8 , 10 ]. Tumor staging was determined utilizing the 8th edition of the AJCC classification, and pathological grade was stratified into low, intermediate, and high categories [ 2 ].…”

“…In our study, we meticulously accounted for numerous potential adverse characteristics, concluding that CRT did not improved OS, it also conferred minimal impact on the risk of locoregional recurrence compared to RT alone, thus offering a supplementary understanding of SGC management. It is worth noting that certain studies did suggest a longer OS in the CRT group compared to the RT group specifically in cases of salivary gland squamous cell carcinoma [ 8 , 15 ]. However, caution is advised in interpreting these results, as the potential inclusion of cases with metastasis from cutaneous malignancies could influence these findings.…”

“…Salivary gland cancer (SGC) is relatively rare, comprising only about 5% of all malignancies in the head and neck region [ 1 ], but it consists of 24 pathologic types based on the newest WHO classification [ 2 ]. Surgery accounts for the mainstay of treatment, according to the NCCN guideline, adjuvant radiotherapy (RT) is usually recommended if there are adverse pathologic features [ 3 ], extensive literature has confirmed RT contributes to improved locoregional control (LRC), disease specific survival, and overall survival (OS) in cases presenting stage T3/4, lymph node (LN) metastasis, high pathologic grade, positive margin, perineural invasion (PNI), lymphovascular invasion (LVI), and extranodal extension (ENE) [ 4 – 8 ].…”

“…The issue of survival benefit associated with CRT in SGCs is a subject of debate within the scientific community. While some researchers have failed to establish a clear association between chemotherapy and prognosis [ 7 , 12 – 14 ], others have observed that, compared to RT alone, CRT may indeed lead to improved outcomes in certain specific pathologic types [ 8 , 15 ]. This discrepancy underscores the complexity of treating SGCs and highlights the need for further research to elucidate the role of adjuvant CRT in optimizing therapeutic outcomes for this rare malignancy.…”

The 8th AJCC classification is inferior to a new neck stage based on intraparotid lymph node in parotid gland cancer

“…The efficacy of adjuvant chemotherapy in salivary gland cancer has been subject to considerable scrutiny, with enhanced outcomes solely documented in the subset of squamous cell carcinoma within salivary gland malignancies. Regrettably, despite extensive inquiry, a definitive association between chemotherapy and prognosis has eluded the majority of researchers, including ourselves [22][23][24].…”