Elsevier

Oral Oncology

Volume 54, March 2016, Pages 75-80
Oral Oncology

Outcomes and prognostic factors for major salivary gland carcinoma following postoperative radiotherapy

https://doi.org/10.1016/j.oraloncology.2015.11.023Get rights and content

Summary

Purpose

To report outcomes of postoperative radiotherapy (PORT) for major salivary gland carcinoma (SGC) and identify patients at high risk of distant metastases (DM).

Methods and materials

Patients with major SGC treated between 2000–2012 were identified. All patients underwent initial primary resection, with neck dissection (ND) therapeutically (if N+) or electively in high risk N0 patients. PORT was delivered using 3D-CRT or IMRT. Multivariable analysis (MVA) assessed predictors for DM, cause-specific (CSS) and overall survival.

Results

Overall 304 patients were identified: 48% stage III–IVB, 22% lymphovascular invasion (LVI), 50% involved margins and 64% high risk pathology. ND was performed in 154 patients (51%). Adjuvant chemotherapy was used in 10 patients (3%). IMRT was delivered in 171 patients (56%) and 3D-CRT in 133 (44%). With a median follow-up of 82 months, the 5-(10-) year local, regional, distant control, CSS and OS were 96% (96%), 95% (94%), 80% (77%), 83% (82%) and 78% (75%), respectively. DM was the most frequent treatment failure (n = 62). On MVA, stage III–IVB and LVI significantly correlated with DM, CSS and OS, while positive margins predicted DM and CSS, and high risk pathology predicted DM. No grade ⩾4 RTOG late toxicity was reported; 9 patients had grade 3, including osteoradionecrosis (n = 4), neck fibrosis (n = 3), trismus (n = 1) and dysphagia (n = 1).

Conclusions

Surgery and PORT with 3D-CRT/IMRT produced excellent long-term outcomes. Further research is required for patients with stage III–IVB, LVI, positive margins and high risk pathology to determine the incremental benefit of systemic therapy in management of SGC.

Highlights

  • PORT with 3D-CRT/IMRT for salivary gland carcinoma achieved excellent outcomes.

  • DM was the most frequent cause of treatment failure and cancer-related mortality.

  • Prognostic factors were stage III–IVB, LVI, R1 and high risk pathology.

  • Further research is required to determine the incremental benefit of chemotherapy.

Introduction

Major salivary gland carcinomas (SGC) represent <5% of all head and neck cancers. These tumors are not only rare but also very heterogeneous, with over 20 histological subtypes with varying prognoses. The mainstay treatment of SGC is surgical resection. In well-selected patients with early-stage, low-risk disease and R0 resections, surgery alone is appropriate. In all other cases, combined modality treatment is recommended [1].

A number of studies have indicated that postoperative radiotherapy (PORT) significantly improved locoregional control (LRC) [2], [3], [4] and survival [5], [6], [7] in SGC patients with adverse pathologic features. However, despite bimodality therapy for aggressive disease, locoregional failure (LRF), distant metastases (DM) and poor survival have been frequently reported for certain prognostic features such as stage III/IV, lymphovascular invasion (LVI), positive surgical margins and high risk pathology [3], [4], [8], [9], [10], [11], [12]. The recognition of these adverse prognostic factors suggests a role for intensifying therapy in this group of patients.

In our institution, intensity modulated radiotherapy (IMRT) has become the standard of care for SGC in the postoperative setting since 2005. The rationale for conducting this study was to retrospectively review patients with major SGC following PORT to describe the clinical outcomes and to identify patients at high risk of DM who might benefit from the addition of chemotherapy or targeted therapy in multimodality management of SGC.

Section snippets

Study population

After institutional research ethics board approval, we identified all patients with previously untreated, pathologically confirmed primary non-metastatic major SGC, treated with curative intent in our institution between 2000 and 2012 with surgery and PORT. Patients younger than 18 years, those with squamous cell carcinoma (SCC) histology and features suggesting nodal spread from an undetected skin primary, and those with minor SGC or patients treated with surgery alone were excluded from this

Patient characteristics

A total of 304 eligible patients with major SGC were identified. The most common primary site was the parotid gland (n = 237; 78%). MEC (n = 56, 18%), ACC (n = 55, 18%), acinic cell (n = 49, 16%) and salivary duct carcinoma (n = 40, 13%) were the most prevalent histologies. High risk pathology was found in 190 patients (64%): ACC (n = 55), salivary duct carcinoma (n = 40), SCC (n = 11), G2/3 adenocarcinoma (n = 15), G2/3 MEC (n = 35), G2/3 carcinoma ex-pleomorphic adenoma (n = 22), and G3 rare histologic subtypes (n =

Discussion

Major SGC constitute rare cancers with diverse histological subtypes. The present study reports our experience in treatment of SGC with surgery and PORT. With this combined modality treatment, we were able to achieve excellent outcomes. Our 5-(10-) year LC, RC, DC, CSS, and OS were 96% (96%), 95% (94%), 80% (77%), 83% (82%) and 78% (75%), respectively; late toxicity was only 3% at both 5 and 10 years. The comparison of our outcomes with those of other institutions is fairly difficult because of

Conclusion

Surgery and PORT with 3D-CRT/IMRT achieved excellent long-term outcomes with low rates of toxicity in SGC. DM was the most frequent cause of treatment failure and cancer-related mortality. Further research is required for patients with stage III–IVB, LVI, positive surgical margins and high risk pathology to determine the incremental benefit of systemic or targeted therapy in multimodality management of SGC.

Conflict of interest

None declared.

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