Early T Stage Salivary Duct Carcinoma: Outcomes and Implications for Patient Counseling

The implicated clinical factors for outcomes in 304 patients with salivary duct carcinoma: Multi-institutional retrospective analysis in Japan

Background

Salivary duct carcinoma (SDC) is a high‐grade salivary malignancy that frequently occurs as the carcinomatous component of carcinoma ex pleomorphic adenoma. We herein examined the clinical factors affecting outcomes in a large cohort of SDC.

Methods

We selected 304 SDC cases and investigated clinical characteristics and the factors affecting outcomes.

Results

The median age of the cases examined was 68 years, the most common primary site was the parotid gland (238 cases), and there was a male predominance (M/F = 5:1). Outcomes were significantly worse when the primary tumor site was the minor salivary glands (SG) than when it was the major SG. Outcomes were also significantly worse in pN(+) cases (161 cases) than in pN0 cases, particularly those with a metastatic lymph node number ≥11. The cumulative incidence of relapse and distant metastases was significantly higher in stage IV cases than in stage 0–III cases.

Conclusions

The absolute number of lymph node metastases, higher stages, and the minor SG as the primary tumor site were identified as factors affecting the outcome of SDC.

Impact of tumor site on the prognosis of salivary gland neoplasms: A systematic review and meta-analysis

In numerous types of cancer, the primary tumor site can show a correlation with disease behavior and survival outcomes. In salivary gland tumors (SGTs) this association remains controversial. This study assessed the association between primary sites of SGTs and prognosis. Studies from five databases were assessed and a meta-analysis was performed using studies that presented 95 % confidence interval (95 % CI), hazard ratio (HR) and survival analysis. Gathered information from 46,361 patients showed that site had a prognostic impact on SGTs. Tumors involving minor salivary glands showed worse overall survival (HR = 1.60; 95 % CI = 1.17-2.19; p = 0.003), disease-specific survival (HR=1.63; 95 % CI = 1.12-2.37; p = 0.01), and cause-specific survival (HR=2.10; 95 % CI = 1.72-2.55; p = 0.00001). Tumors from major salivary glands showed better recurrence-free survival (HR=2.31; 95 % CI = 1.77-3.02; p = 0.00001), and locoregional control of disease (HR=2.66; 95 % CI = 1.20-5.91; p = 0.02). Our results showed that the primary site of SGTs has an impact on patient prognosis.

VDR in salivary gland homeostasis and cancer

The vitamin D receptor (VDR) and its ligand 1,25(OH)₂D₃ (1,25D) impact differentiation and exert anti-tumor effects in many tissues, but its role in salivary gland has yet to be defined. Using immunohistochemistry (IHC), we have detected strong VDR expression in murine and human salivary gland ducts. Compared to normal gland, VDR protein expression was retained in differentiated human pleomorphic adenoma (PA) but was undetectable in undifferentiated PA and in carcinomas, suggesting deregulation of VDR during salivary cancer progression. To gain insight into the potential role of VDR in salivary cancer, we assessed the effects of vitamin D in vivo and in vitro. Despite the presence of VDR in salivary gland, chronic dietary vitamin D restriction did not alter morphology of the salivary epithelium in C57/Bl6 mice. The localization of VDR in ductal epithelium prompted us to examine the effects of 1,25D in an established cell line (mSGc) derived from normal murine submandibular gland (SMG). This previously characterized cell line consists of multiple stem, progenitor and differentiated cell types as determined by mutually exclusive cellular expression of basal, ductal and myoepithelial markers. We demonstrated VDR expression and regulation of VDR target genes Vdr and Postn by 1,25D in mSGc, indicating functional ligand-mediated transcriptional activity. The effect of VDR signaling on epithelial differentiation markers was assessed by qPCR and IHC in mSGc cells treated with 1,25D. We found that 1,25D reduced mRNA expression of the basal cell progenitor marker keratin 5 (K5) and increased expression of the differentiated ductal cell marker keratin 7 (K7). Further, we found that 1,25D significantly decreased the number of proliferating cells, including proliferating K5⁺ cells. Characterization of cell cycle by Muse cytometry indicated 1,25D treatment decreased cells in S, G₂, and M phase. The inhibition of K5⁺ cell proliferation by 1,25D is of particular interest because K5⁺ basal cells contribute to a wide variety of salivary tumor types. Our studies suggest that 1,25D alters cancer-relevant progenitor and differentiation markers in the salivary gland.

Intraductal carcinomas of the salivary glands: systematic review and classification of 93 published cases

Intraductal carcinomas (IDCs) are rare, not well-characterized salivary gland tumors. A systematic literature review of pure IDCs (without stromal invasion) of low-grade (LG-IDCs) or high-grade (HG-IDCs) was performed: IDCs were classified using the apocrine (AR+/S100-) vs intercalated (S100+/AR-) classification. Eighty-two LG-IDCs and 11 HG-IDCs were identified (84% parotid; 11% oral; 3% submandibular; 1% lacrimal; and 1% unknown). Out of 11 HG-IDCs, 2 HG-IDCs (18%) recurred as HG-IDC or invasive carcinoma. IDCs were classified as follows: intercalated (30%); mixed apocrine and intercalated (27%); apocrine (11%); oncocytic (6%); intercalated with focal oncocytic features (1%); and unclassifiable (25%). Double AR/S100 expressors (4%) or discrepancies between morphology and immunophenotype (9%) were found. Apocrine features and necrosis were more frequent in HG-IDCs (55%; 45%). Pleomorphism favored HG-IDCs (especially when combined with >10 mitoses/10 HPFs and/or Ki67 index >10%), being associated with apocrine areas at least in 3 HG-IDCs (27%). IDCs were typically mammaglobin+/ER-/PR-/DOG1-. No immunomarker clearly distinguished HG-IDCs from LG-IDCs. About 57% IDCs (16 LG-IDCs, 1 HG-IDC) showed RET rearrangements, including NCOA4-RET (eight intercalated and two unclassifiable IDCs) and TRIM27-RET fusions (two mixed IDCs). No ETV6, ALK-1, ROS, NTRK3, MAML2, MAML3, or PLAG1 rearrangements were identified. Complete excision and total sampling should exclude invasive areas.

Intensity Modulated Radiotherapy (IMRT) With Carbon Ion Boost in the Multimodal Treatment of Salivary Duct Carcinoma

Background: To assess outcomes and treatment related toxicity following intensity-modulated radiotherapy (IMRT) and a Carbon Ion Radiotherapy (CIRT) boost for salivary duct carcinoma (SDC).

Methods: Twenty-eight consecutive patients with SDC who underwent a postoperative (82%) or definitive (18%) radiation therapy between 2010 and 2017 were assessed in this retrospective single-center analysis. CIRT boost was delivered with median 18 Gy(RBE) in 6 daily fractions, followed by an TomoTherapy^®-based IMRT (median 54 Gy in 27 daily fractions). Treatment-related acute toxicity was assessed according to CTCAE Version 4.

Results: Tumors were most commonly located in the major salivary glands (n = 25; 89%); 23 patients (82%) received previous surgery (R0: 30%; R1: 57%; R2: 4%; RX: 19%). Median follow-up was 30 months. Four patients (14%) experienced a local relapse and 3 (11%) developed locoregional recurrence. The two-year local control (LC) and locoregional control (LRC) was 96 and 93%, respectively. Median disease-free survival (DFS) was 27 months, metastasis-free survival (MFS) was 69 months, and overall survival (OS) was 93 months. Acute grade 3 toxicity occurred in 11 patients (mucositis, dermatitis, xerostomia; n = 2 each (7%) were the most common) and 2 osteonecroses of the mandibular (grade 3) occurred. No patients experienced grade ≥4 toxicities.

Conclusions: Multimodal therapy approaches with surgery followed by IMRT and CIRT boost for SDC leads to good local and locoregional disease control. However, the frequent occurrence of distant metastases limits the prognosis and requires optimization of adjuvant systemic therapies.

Intermediate-grade carcinoma of the parotid and the impact of adjuvant radiation

PURPOSE

To determine the influence of adjuvant radiotherapy on survival in surgically-managed early stage intermediate-grade mucoepidermoid and acinic cell carcinoma of the parotid.

MATERIALS AND METHODS

The National Cancer Database was reviewed between 2004 and 2015 to identify patients with intermediate-grade, early T-stage, node-negative parotid carcinoma who underwent parotidectomy ± radiotherapy.

RESULTS

There were 744 patients identified of which 81% had mucoepidermoid carcinoma and 19% had acinic cell carcinoma. Positive surgical margins were identified in 21% and adjuvant radiotherapy was administered in 38% of cases. Of the 159 patients with positive margins, 113 (71%) received adjuvant radiotherapy. Of the 585 patients with negative margins, 173 (30%) underwent adjuvant radiotherapy. In multivariable analysis, age (over 52 years: HR 5.19, 95%CI 2.33-11.57), insurance status (private insurance: HR 0.24 95%CI 0.13-0.43), and extent of parotidectomy (total parotidectomy: HR 2.02 95%CI 1.23-3.31) were significantly associated with overall survival, while adjuvant radiotherapy was not a significant predictive factor (HR 0.81, 95%CI 0.49-1.36). In patients with positive margin resections, however, adjuvant radiation was an independent predictor of improved survival when adjusted for age, insurance status, and extent of parotidectomy (HR 0.34, 95%CI 0.13-0.88). Conversely, in patients with negative margin resections, adjuvant radiation did not influence survival outcomes when adjusted for these covariates (HR 1.02, 95%CI 0.53-1.93).

CONCLUSIONS AND RELEVANCE

In patients with early stage intermediate-grade parotid carcinoma, adjuvant radiotherapy significantly and independently improves survival in those with post-operative positive margins. Adjuvant therapy, however, does not appear to improve survival outcomes in those with negative margin resections.

Data Set for the Reporting of Carcinomas of the Major Salivary Glands: Explanations and Recommendations of the Guidelines From the International Collaboration on Cancer Reporting

The International Collaboration on Cancer Reporting is a nonprofit organization whose goal is to develop evidence-based, internationally agreed-upon standardized data sets for each anatomic site, to be used throughout the world. Providing global standardization of pathology tumor classification, staging, and other reporting elements will lead to achieving the objective of improved patient management and enhanced epidemiologic research. Salivary gland carcinomas are relatively uncommon, and as such, meaningful data about the many histologic types are not easily compared. Morphologic overlap between tumor types makes accurate classification challenging, but there are often significant differences in patient outcomes. Therefore, issues related to tumor type, tumor grading, high-grade transformation, extent of invasion, number and size of nerves affected, and types of ancillary studies are discussed in the context of daily application to specimens from these organs. This review focuses on the data set developed for salivary gland carcinomas with discussion of the key core and noncore elements developed for inclusion by an international expert panel of head and neck and oral-maxillofacial pathologists and surgeons.

Salivary duct carcinoma

PURPOSE OF REVIEW

The review puts new information on geno- and phenotype of salivary duct carcinoma (SDC) in the perspective of the updated 2017 WHO classification.

RECENT FINDINGS

The proportion of SDC is increasing. This may be because of a true rise in incidence, but certainly to better diagnostic tests and changed WHO definitions. In this light, a substantial proportion of carcinoma expleomorphic adenoma is now attributed to the category of SDC. 'Low-grade SDC' and 'SDC in-situ' of the former WHO classification, are now named low-grade and high-grade intraductal carcinoma (IDC), respectively. Recent series quantify biologic aggressiveness: perineural growth, vascular invasion, and extracapsular extension in lymph node metastasis are each observed in two out of three patients with SDC. Most patients die within 3 years, but once 5-year disease-free survival is reached, further disease activity is exceptional. The typical molecular biological profile with high human epidermal growth factor receptor 2 and androgen receptor expression is increasingly successfully exploited in clinical trials for advanced SDC.

SUMMARY

The aggressive SDC is increasingly diagnosed. Despite intensive combined surgery and radiation therapy, many patients recur, for whom new bullets, targeting the molecular biological mechanisms, are the subject of ongoing clinical trials.

Extracapsular extension is not a significant prognostic indicator in non-squamous cancers of the major salivary glands

Background

Extracapsular extension (ECE) is a well-established prognostic feature in squamous cell cancers of the head and neck. Although some extrapolate data from mucosal head and neck cancer to include ECE as a high-risk feature in salivary gland cancers, data is lacking about ECE’s prognostic value for these malignancies. We investigate whether ECE is a significant prognostic indicator in pathologic node-positive cancers of the major salivary glands.

Methods

A retrospective study of adult salivary gland cancer cases diagnosed from 2004 to 2013 in the NCDB was conducted. Demographic, tumor, treatment, and survival variables were included in the study. Univariate Kaplan-Meier analyses, as well as multivariate Cox survival regressions were performed.

Results

Positive ECE status was associated with significantly worse survival in salivary SCC (HR 1.687; p = 0.002) but not non-squamous salivary cancers (HR 1.000; p = 0.998) on multivariate analysis. While post-operative radiotherapy was not associated with improved survival for patients without high-risk adverse features (high grade or positive surgical margins), its use was associated with better survival for ECE-positive salivary SCC patients without one of these additional adverse features (HR 0.064; p = 0.010).

Conclusions

Although ECE is a significant prognostic indicator in salivary SCC, its prognostic significance for non-squamous salivary cancers may be limited. Radiotherapy may improve survival in cases with at least one high-risk adverse feature: high grade; positive surgical margins; and for salivary SCC specifically, positive ECE status.

Treatment outcomes in metastatic and localized high-grade salivary gland cancer: high chance of cure with surgery and post-operative radiation in T1-2 N0 high-grade salivary gland cancer

BACKGROUND

High-grade salivary gland cancer is a distinct clinical entity that has aggressive disease progression and early systemic spread. However, because of the rarity of the disease, the clinical outcomes, prognostic factors and clinical decision on the optimal treatments have not been fully understood.

METHODS

In this study, we retrospectively analyzed the clinical data of 124 patients with high-grade salivary gland cancers and performed multivariate survival analyses to evaluate the clinico-pathological factors affecting the treatment outcomes.

RESULTS

The 5-year disease-specific survival was 63.4% in patients with high-grade salivary gland cancers. Among the clinico-pathological factors, presence of lymph node metastasis (hazard ratio 5.63, 95% confidence interval 2.64-12.03, P < 0.001) and distant metastasis (hazard ratio 4.59, 95% confidence interval 2.10-10.04, P < 0.001) at diagnosis were the most potent unfavorable prognostic factors. Importantly, patients with early-stage disease (T1-2N0M0) showed apparently a relatively excellent prognosis (93.2% 5-year disease-specific survival); meanwhile N (+) and M1 status at diagnosis resulted in dismal outcomes (44.6 and 21.1% 5-year disease-specific survival, respectively). On comparing surgery alone as a treatment modality, surgery plus postoperative radiation significantly benefited the patients, but the difference between adjuvant radiation and chemoradiation was not found to be significant. Pathological subtypes of high-grade salivary gland cancers were not significantly associated with prognosis.

CONCLUSIONS

Despite of an overall unfavorable prognosis in high-grade salivary gland cancer, patients with early-stage disease are expected to have excellent prognosis (over 90% survival rates) with surgery plus adjuvant radiation, which may implicate the patients' consultation, therapeutic decision making, and the need for early detection of the disease.

Cervical Lymph Node Metastatic Status and Adjuvant Therapy Predict the Prognosis of Salivary Duct Carcinoma

PURPOSE

Salivary duct carcinoma (SDC) is an aggressive malignancy that is not yet fully understood. We designed the present retrospective study to investigate the factors affecting the prognosis of SDC and the effects of adjuvant therapies on the clinical outcomes of patients.

MATERIALS AND METHODS

Patients with SDC treated surgically from 2006 to 2016 were enrolled in the present retrospective cohort study. The demographic data, clinical pathologic characteristics, and follow-up results were recorded. The prognostic indicators of overall survival (OS), locoregional failure-free survival (LRFFS), and distant metastasis-free survival (DMFS) were analyzed using the Kaplan-Meier method and the Cox proportional hazard model.

RESULTS

The study sample included 66 patients, most of whom were male (81.8%). The 5-year OS, LRFFS, and DMFS for all patients was 52.5%, 63.9%, and 51.3%, respectively. Univariate analysis showed that stage N2-N3, lymph node involvement of levels IV and V, 8 or more positive lymph nodes, and extranodal extension were all negative prognostic indicators for OS. The only significant indicator on multivariate analysis was the number of positive lymph nodes. Multivariate analysis revealed that extracapsular invasion and no adjuvant radiotherapy were risk factors for LRFFS. In contrast, lesions involving both glands and 8 or more positive lymph nodes were prognostic factors for DMFS. Further subgroup analysis showed that radiotherapy was only useful for patients with locally advanced lesions for local control.

CONCLUSIONS

Cervical lymph node metastatic status is an important factor in predicting the prognosis of SDC patients. Adjuvant radiotherapy is useful for local control, especially for patients with stage T4 disease but does not benefit OS and DMFS.

Salivary duct carcinoma: An aggressive salivary gland malignancy with opportunities for targeted therapy

Salivary duct carcinoma (SDC) is a rare, aggressive salivary malignancy that is often diagnosed at an advanced stage. Previously, little was known about outcomes of this disease due to its rarity. In the past several years, much has been learned about salivary duct carcinoma after publication of outcomes from several large single-institution series and national database searches. Recent studies of genomic alterations have helped elucidate the biology and pathogenesis of this aggressive disease. Here we review outcomes of the disease, effects of treatment, prognostic factors, and genomic alterations in SDC. Studies of targeted therapy and promising future directions are also discussed.