Outcomes of patients in nasopharyngeal adenoid cystic carcinoma in the IMRT era: a single-center experience.

OBJECTIVE: Nasopharyngeal adenoid cystic carcinoma (NACC) is a rare malignancy with special biological features. Controversies exist regarding the treatment approach and prognostic factors in the IMRT era. This study aimed to evaluate the long-term outcomes and management approaches in NACC. METHODS: Fifty patients with NACC at our institution between 2010 and 2020 were reviewed. Sixteen patients received primary radiotherapy (RT), and 34 patients underwent primary surgery. RESULTS: Between January 2010 and October 2020, a total of 50 patients with pathologically proven NACC were included in our analysis. The median follow-up time was 58.5 months (range: 6.0-151.0 months). The 5-year overall survival rate (OS) and progression-free survival rate (PFS) were 83.9% and 67.5%, respectively. The 5-year OS rates of patients whose primary treatment was surgery and RT were 90.0% and 67.3%, respectively (log-rank P = 0.028). The 5-year PFS rates of patients whose primary treatment was surgery or RT were 80.8% and 40.7%, respectively (log-rank P = 0.024). Multivariate analyses showed that nerve invasion and the pattern of primary treatment were independent factors associated with PFS. CONCLUSIONS: Due to the relative insensitivity to radiation, primary surgery seemed to provide a better chance of disease control and improved survival in NACC. Meanwhile, postoperative radiotherapy should be performed for advanced stage or residual tumours. Cranial nerve invasion and treatment pattern might be important factors affecting the prognosis of patients with NACC.

Cylindroma of the Breast: A Rare Differential for Breast Cancer on Core Biopsies, Case Report and Review of Literature.

Breast cancers of either ductal or lobular pathology make up the vast majority of breast malignancies. Other cancers occur rarely in the breast. Benign pathology can at times mimic breast cancers on imaging and initial needle biopsies. We report a rare breast pathology of cylindroma. Cylindromas are usually benign, rare dermatologic lesions most commonly associated with head or neck locations. They more commonly occur as sporadic and solitary masses. Less commonly is an autosomal-dominant multi-centric form of this disease. Malignant cylindromas are very rare. We present a patient with findings of a cylindroma of the breast after excision. This was initially felt to be concerning for breast cancer on imaging and core biopsy. Treatment of cylindromas of the breast is excision. Sentinel lymph node dissection is not indicated, nor are adjuvant therapies when identified in the breast. This lesion needs to be included in the differential diagnosis for breast cancer. If cylindromas can be accurately diagnosed preoperatively, this would negate the need for consideration of axillary nodal surgery and adjuvant therapies.

A population study comparing tracheal and lung adenoid cystic carcinoma.

BACKGROUND: Thoracic adenoid cystic carcinoma (ACC) is rare, and the differences between tracheal and lung lesions have not been fully understood. METHODS: Patients were identified from a Chinese cancer center (FUSCC) (2005-2022) and the Surveillance, Epidemiology, and End Results (SEER) database (2000-2019). Incidence was calculated and trends were quantified. Clinicopathological features and overall survival (OS) were analyzed. Nomograms predicting OS were constructed. RESULTS: Totally, 55 tracheal adenoid cystic carcinoma (TACC) and 25 lung and bronchus adenoid cystic carcinoma (LACC) were included in a Chinese cohort, 121 TACC and 162 LACC included in the SEER cohort. There were larger tumor sizes, more lymph nodes and distant metastases for LACC than TACC patients. TACC patients are more likely to get local treatments. Patients with LACC had significantly worse median OS than patients with TACC (SEER cohort: 68.0 months vs. 109.0 months, p = 0.001, Chinese cohort: 62.9 months vs. 124.8 months, p = 0.061). Age, lymph node metastasis, distant metastasis and local treatment were identified as independent prognostic factors for OS of TACC. Distant metastasis and local treatment were identified for LACC. Specifically, surgery alone or in combination with radiotherapy is crucial for improving survival in both TACC and LACC. Only TACC benefits from radiotherapy alone, while chemotherapy does not improve survival for either. The nomograms constructed using these factors revealed good prognostic accuracy. CONCLUSIONS: LACC is more aggressive and has a worse prognosis than TACC. TACC patients have more opportunities for local treatment, which is important for the prognosis of both TACC and LACC. Nomograms were created for TACC and LACC to aid in personalized survival predictions and clinical decisions.

Tracheobronchial Adenoid Cystic Carcinoma Treated Successfully With Chemoradiotherapy Followed by Durvalumab: A Case Report.

BACKGROUND/AIM: Tracheobronchial adenoid cystic carcinoma (ACC) is a rare type of malignancy. Although complete resection is standard treatment for localized ACC, treatment for unresectable ACC has not been established. It is unclear whether concurrent chemoradiotherapy (CCRT) followed by immune checkpoint inhibitor (ICI) therapy is effective for ACC. CASE REPORT: A 49-year-old man was admitted to our hospital for the treatment of dyspnea and thickening of the bronchial wall from the tracheal carina to the left main bronchus, as observed on a CT scan. Systemic examinations and transbronchial biopsy led to a diagnosis of locally advanced ACC. Although radiotherapy and chemotherapy are not regarded as very sensitive for ACC, a favorable response was obtained with CCRT. Following CCRT, he received ICI therapy with durvalumab for 1 year. The patient has remained in a stable condition 18 months after therapy, with no recurrence. CONCLUSION: ICI after CCRT might be a promising treatment option for unresectable tracheobronchial ACC.

Molecular Aspects of Mucoepidermoid Carcinoma and Adenoid Cystic Carcinoma of the Salivary Gland.

BACKGROUND: Salivary gland tumors (SGTs) are rare and highly heterogeneous lesions, making diagnosis a challenging activity. In addition, the small number of studies and samples evaluated difficults the determination of prognosis and diagnosis. Despite the solid advances achieved by research, there is still an intense need to investigate biomarkers for diagnosis, prognosis and that explain the evolution and progression of SGTs. METHODS: We performed a comprehensive literature review of the molecular alterations focusing on the most frequent malignant SGTs: mucoepidermoid carcinoma and adenoid cystic carcinoma. RESULTS: Due to the importance of biomarkers in the tumorigenenic process, this review aimed to address the mechanisms involved and to describe molecular and biomarker pathways to better understand some aspects of the pathophysiology of salivary gland tumorigenesis. CONCLUSIONS: Molecular analysis is essential not only to improve the diagnosis and prognosis of the tumors but also to identify novel driver pathways in the precision medicine scenario.

Endotracheal enucleation and para-toluenesulfonamide injection for adenoid cystic carcinoma in the upper trachea: A novel therapeutic approach.

We present a case of an adenoid cystic carcinoma (ACC) located in the upper trachea, which resulted in significant airway blockage, that was unsuitable for surgical removal due to concerns about functional impairment. Instead, endotracheal enucleation via rigid bronchoscopy was performed initially, followed by the injection of a novel tumor ablation agent known as para-toluenesulfonamide (PTS). We detail the dosing regimen, effectiveness evaluation, and post-treatment follow-up. The study highlights the potential of PTS injection as a viable alternative treatment option for patients with ACC who cannot undergo surgical resection and feasibility of lipiodol to monitor treatment effect. This research adds to the existing knowledge on ACC treatment and provides new therapeutic possibilities for patients with tracheal ACC.

Immunohistochemical marker profiles for the differentiation of collagenous spherulosis from adenoid cystic carcinoma of the breast.

Collagenous spherulosis (CS) is a rare breast lesion of unknown histogenesis. Adenoid cystic carcinoma (ACC) is a rare basal-like breast carcinoma with low histological grade. CS is a benign lesion but resembles ACC. Both lesions show a similar histomorphology and feature bilineage differentiation. This study compared immunohistochemical markers in CS and ACC. We compiled n = 13 CS cases and n = 18 mammary ACCs. Fourteen marker proteins (ER, PR, HER2, GATA3, CK7, E-cadherin, CD117, CK5/14, p40, p63, SMA, CD10, calponin, P-cadherin) were evaluated by immunohistochemistry (IHC). MYB rearrangement, a common alteration in ACC, was assessed by fluorescence in situ hybridization. Patient age ranged between 40-60 years for CS lesions and 30-90 years for ACCs. 7/13 (54%) CS cases harbored a lobular carcinoma in situ (LCIS) in the luminal component. One CS/LCIS lesion occurred in a carrier of a pathogenic germline variant in CDH1/E-cadherin. MYB rearrangement was detected in 0/11 (0%) CS and 6/16 (37%) ACC cases (P = 0.054). CS was associated with expression of ER in the luminal component (P < 0.001), E-cadherin loss in the luminal component (P = 0.045), and expression of CD10 and calponin in the basal component (P < 0.001). Furthermore, CS was associated with GATA3 expression in the luminal component (12/13 [92%] versus 5/18 [27%], P < 0.001). In summary, IHC for GATA3 and E-cadherin may contribute to the differential diagnosis between CS and ACC, although these markers are not exclusively expressed in either lesion. Histologic evaluation has to take into account that CS is frequently colonized by LCIS, requiring thorough correlation of histomorphology and immunohistochemical features.

Adenoid Cystic Carcinoma, Clinical Presentation, Current Treatment and Approaches Towards Novel Therapies.

Adenoid cystic carcinoma (AdCC) is a rare cancer originating from secretory glands with unknown aetiology. It is one of the most dominant malignant salivary tumours (MST). However, it can arise in other areas of the head and neck region and in secretory glands outside this area. It occurs at all ages, but is more frequent between 50-70 years of age and more common in females than in males. The symptoms of AdCC are generally unspecific and the clinical diagnosis of AdCC maybe challenging, partially due to its heterogenous histopathology and indolent growth. Moreover, there is a lack of good prognostic markers, and due to its rarity, it is difficult to predict which therapeutic methods are the most optimal for each patient, especially since very late recurrences occur. This review presents some major characteristics of AdCC and some current treatments for this disease.

SALTT study: A retrospective analysis of 111 SAlivary gland tumors of Lung and Tracheobronchial Tree.

INTRODUCTION: Primary pulmonary salivary gland-type tumours (PPSGT) are rare lung neoplasms arising from submucosal seromucinous glands in the central airway. METHODS AND RESULTS: We retrospectively analysed the clinicopathological features of 111 PPSGTs diagnosed at our institute between 2003 and 2021. The mean age at diagnosis was 43.8 years(range 6-78 years) and a male-to-female ratio of 2:1. On imaging, 92 % of cases had centrally located tumours and 37.3 % were early stage. The histopathological types included 70 cases (63 %) of mucoepidermoid carcinoma (MEC), 31 cases (27.7 %) of adenoid cystic carcinoma (ADCC), two cases of myoepithelial carcinoma, one case each of acinic cell carcinoma (ACC), clear cell carcinoma (CCC), epithelial myoepithelial carcinoma (EMC) and 5 others [including adenocarcinoma of minor salivary gland origin(n = 3), carcinoma with sebaceous differentiation(n = 1) and poorly differentiated carcinoma of salivary gland type(n = 1)]. The size of the tumours found in the resection specimens ranged from 1 cm to 13 cm, with an average size of 4.9 cm. High-risk attributes such as lymphovascular invasion (LVI), perineural invasion (PNI), pleural involvement, positive resection margins, and nodal metastasis were identified in 15.3 %, 15.3 %, 13.6 %,15.2 % and 6.7 % of cases, respectively. These attributes were found to be more frequent in ADCC than in MEC. Surgery was the main treatment modality [68/84 (80 %) cases]. ADCC cases had more recurrence and distant metastasis than MEC cases. The 3- year overall-survival (OS) and recurrence-free survival(RFS) were better in patients with age lesser than 60 years(p-value <0.0001), low pT stage (p-value 0.00038) and lower grade of MEC(p-value-0.0067). CONCLUSION: It is crucial to have an acquaintance with the morphologic spectrum and immunophenotypic characteristics of PPSGT to recognize them in this unusual location. In tandem, it is crucial to differentiate them from conventional primary non-small cell lung carcinoma, as the management protocols and prognostic implications differ significantly.

HSP27 promotes vasculogenic mimicry formation in human salivary adenoid cystic carcinoma via the AKT-MMP-2/9 pathway.

PURPOSE: To explore the role and mechanism of heat shock protein 27 (HSP27) in SACC VM formation. STUDY DESIGN: Immunohistochemistry and double staining with cluster of differentiation 31 (CD31) and periodic acid-Schiff (PAS) were used to detect HSP27 expression and VM in 70 SACC tissue samples separately. Quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and immunofluorescence were used to detect gene and protein expression. HSP27 in SACC cells were overexpression or downregulated by transfecting HSP27 or short hairpin RNA target HSP27 (sh-HSP27). The migration and invasion abilities of SACC cells were detected using wound healing and Transwell invasion assays. The VM formation ability of the cells in vitro was detected using a Matrigel 3-dimensional culture. RESULTS: HSP27 expression was positively correlated with VM formation and affected the prognosis of patients. In vitro, HSP27 upregulation engendered VM formation and the invasion and migration of SACC cells. Mechanistically, HSP27 upregulation increased Akt phosphorylation and subsequently increased downstream matrix metalloproteinase 2 and 9 expressions. CONCLUSION: HSP27 may plays an important role in VM formation in SACC via the AKT-MMP-2/9 signalling pathway.

Twelve years after: The french national network on rare head and neck tumours (REFCOR).

BACKGROUND: Rare cancers constitute less than 10% of head and neck cancers and lack sufficient evidence for standardized care. The French Rare Head and Neck Cancer Expert Network (REFCOR) as established a national database to collect data on these rare cancers. This study aims to describe patient and tumour characteristics in this database. METHODS: Prospective data collection was conducted across multiple centers. Survival analyses were performed using Kaplan Meier method and Log Rank test. Odds ratios were used for comparing proportions. RESULTS: A total of 7208 patients were included over a period of 10 years. The most frequent histologies were: Not Otherwise Specified (NOS) adenocarcinoma 13 %, adenoid cystic carcinoma 12 %, squamous cell carcinoma of rare locations 10 %, mucoepidermoid carcinoma 9 %, intestinal-type adenocarcinoma (8 %). Tumours were located in sinonasal area (38 %); salivary glands (32 %); oral cavity / oropharynx / nasopharynx (16 %); larynx / hypopharynx (3 %); ears (1 %); others (3 %). Tumours were predominantly classified as T4 (23 %), N0 (54 %), and M0 (62 %). Primary treatment approach involved tumour resection (78 %) and / or radiotherapy (63 %). Patients with salivary gland cancers exhibited better 5-year overall survival (OS) rates (p < 0.05), and lower recurrence rates compared to patients with sinonasal, laryngeal/ hypopharyngeal cancers. No significant differences were observed in the other comparisons. Acinar cell carcinoma demonstrated the best OS while mucous melanoma had the poorest prognosis. CONCLUSION: Melanoma, carcinoma NOS, and sinonasal undifferenciated carcinoma still have poor prognoses. Efforts are being made, including training and guidelines, to expand network coverage (REFCOR, EURACAN), improve data collection and contribute to personalized therapies.

Differential expression of TRKB tyrosine kinase in the two histological types of parotid salivary duct carcinoma with cancer aggressiveness.

Parotid salivary duct carcinoma (SDC) is a rare and aggressive parotid gland carcinoma (PGC). SDC has two origins: de novo and ex pleomorphic adenoma (SDC ex PA); however, because of its rarity, the clinical and molecular features of the two types of SDC are not sufficiently understood. Here, we studied the differences in their clinicopathological and molecular features using clinical specimens while comparing them to those of adenoid cystic carcinoma (AdCC), an intermediate-grade PGC. Clinicopathological analysis of tissues from patients with PGC revealed significant associations between histological types and malignant phenotypes, including nodal metastasis, recurrence, vascular invasion, and neural invasion, and revealed more malignant phenotypes of de novo SDC than of SDC ex PA. The de novo SDC showed a significantly higher frequency of intra-neural invasion (intra-NI) and vascular invasion than AdCC and SDC ex PA. PGCs with high intra-NI were significantly correlated with malignant phenotypes and survival rates. Recently, we observed the overexpression of tropomyosin receptor kinase B (TRKB), a receptor tyrosine kinase, in PGC cells. Here, immunohistochemical and clinicopathological analyses showed that TRKB was highly expressed in SDC cells, particularly de novo SDC cells, and was significantly associated with poor survival and highly malignant phenotypes, including intra-NI and vascular invasion. Collectively, these data show that TRKB expression is significantly elevated in PGC, particularly in de novo SDC, and can be one of the biomarkers of their aggressiveness.

MYB alternative promoter activity is increased in adenoid cystic carcinoma metastases and is associated with a specific gene expression signature.

OBJECTIVE: Adenoid cystic carcinoma (ACC) is a head and neck cancer with a poor long-term prognosis that shows frequent local recurrences and distant metastases. The tumors are characterized by MYB oncogene activation and are notoriously unresponsive to systemic therapies. The biological underpinnings behind therapy resistance of disseminated ACC are largely unknown. Here, we have studied the molecular and clinical significance of MYB alternative promoter (TSS2) usage in ACC metastases. MATERIALS AND METHODS: MYB TSS2 activity was investigated in primary tumors and metastases from 26 ACC patients using RNA-sequencing and quantitative real-time PCR analysis. Differences in global gene expression between MYB TSS2 high and low cases were studied, and pathway analyses were performed. RESULTS: MYB TSS2 activity was significantly higher in ACC metastases than in primary tumors (median activity 15.1 vs 3.0, P = 0.0003). MYB TSS2 high ACC metastases showed a specific gene expression signature, including increased expression of multi-drug resistance genes and canonical MYB target genes, and suppression of the p53 and NOTCH pathways. CONCLUSIONS: Collectively, our findings indicate that elevated MYB TSS2 activity is associated with metastases, potential drug resistance, and augmented MYB-driven gene expression in ACC. Our study advocates the need for new therapies that specifically target MYB and drug resistance mechanisms in disseminated ACC.

Prognosis of primary breast salivary gland-type carcinoma: a propensity score-matching analysis with invasive carcinoma of no special type based on the SEER database for years 2010-2020.

BACKGROUND: Primary breast salivary gland-type carcinoma has weak evidence to support its management due to its rare occurrence and limited data regarding its clinicopathological features and prognosis. Therefore, this study aimed to assess clinicopathological features and prognosis for this type of carcinoma diagnosed over the past decade and compared those to the common breast invasive carcinoma of no special type (NST). METHODS: This study used the Surveillance, Epidemiology, and End Results (SEER) database to extract data regarding primary breast salivary gland-type carcinoma. Using a propensity score-matching approach, the prognosis was compared with invasive carcinoma, NST. RESULTS: This study included 488 cases of salivary gland-type carcinoma and 375,660 cases of invasive carcinoma, NST, giving an occurrence ratio of 1 to 770. Adenoid cystic carcinoma (81%) formed the majority of salivary gland-type carcinoma, followed by secretory carcinoma (13%). For salivary gland-type carcinoma, acinic cell carcinoma histological type, tumor grade 3, HER2-overexpressed status, and higher AJCC stage groups were significant worse prognostic factors for breast cancer-specific survival in univariate analyses (p < 0.05). Nonetheless, tumor grade 3 and higher AJCC stage groups remained as significant independent prognostic factors in multivariate analysis (p < 0.05). The apparent better breast cancer-specific survival of salivary gland-type carcinoma as compared to that of invasive carcinoma, NST, was diminished following adjustment for differences in baseline clinicopathological features and treatment-related variables. CONCLUSIONS: This study suggests that when managing primary breast salivary gland-type carcinoma, greater emphasis should be given to the tumor grade and AJCC stage group in addition to acinic cell carcinoma histological type and HER2 overexpression. Conventional prognostic factors are important as salivary gland-type carcinoma had similar prognosis as invasive carcinoma, NST, following adjustment for confounding variables.

Salivary gland adenoid cystic carcinoma in the U.S population: Importance of grade, site of metastases, and adjuvant radiation for survival.

BACKGROUND: Adenoid cystic carcinoma (AdCC) is a rare and relatively heterogenous salivary gland malignancy, for which there is debate regarding grading, and clinical prognostic factors, including the role of adjuvant radiotherapy. METHODS: Surveillance, Epidemiology, and End Results (SEER) data were reviewed for AdCC cases from 2000 to 2018. RESULTS: A total of 1978 patients with AdCC were identified. Most patients were between 50 and 59 years of age (21.4 %), female (59.9 %), and Caucasian (76.8 %). Most tumors were localized at presentation (44.3 %), and moderately differentiated (or grade II) (43.7 %). Overall and DSS 5-year survival rates were 70.7 % (95 % CI, 69.9-78.8), and 78.6 % (95 % CI, 77.6-79.6). The best overall 5-year survival rate was observed for those treated with surgery plus radiation, 76.8 % (95 % CI, 75.5-78.1). Multivariate analysis revealed male sex, age > 65 (H.R. 2.659 (95 % CI,2.291-3.098), p < .001), grade III/IV (H.R.5.172 (95 % CI, 3.418-7.824), p < .001), nodal metastasis, distant metastasis (H.R. 2.400 (95 % CI, 2.178-2.645), p < .001), chemotherapy only, and combination therapy as negative prognostic factors, and receiving surgery plus radiation therapy (H.R.0.586 (95 % CI, 0.505-0.679), p < .001) as a positive prognostic factor. When limited just to the lungs, had much better survival than those patients with distant metastases to other sites such as the bones and liver (p < .001). CONCLUSION: This SEER study identifies grade, particularly III and IV, to be the strongest single predictor of worse survival. Patients did best when treated with surgery and postoperative radiotherapy. These results can inform future management of patients with this challenging cancer type.

Salivary gland-type cancers: cross-organ demographics of a rare cancer.

BACKGROUND: Salivary gland-type cancers (SGTCs) are histologically heterogeneous and can affect organs other than the salivary glands. Some tumors outside the salivary glands are diagnosed on their unique histological characteristics. Comprehensive cross-organ studies on SGTCs are limited. METHODS: We retrospectively analyzed the data of patients with salivary duct carcinoma (SDC), adenoid cystic carcinoma (AdCC), mucoepidermoid carcinoma (MEC), epithelial-myoepithelial carcinoma (EMC), acinic cell carcinoma (AcCC), and polymorphous adenocarcinoma (PAC) who visited our institution between 2009 and 2019. The primary tumor sites were classified into four categories; major salivary glands, head/neck (H/N) excluding (exc) major salivary glands (MSG) regions, broncho-pulmonary regions, and "others". H/N exc MSG was further divided into three subcategories, nasal/paranasal sinus, oral and pharynx/larynx. RESULTS: We identified 173 patients with SGTCs, with SDC, AdCC, MEC, EMC, AcCC, and PAC accounting for 20%, 42%, 27%, 3%, 8%, and 1% of the cases, respectively. The most frequent primary site was the major salivary glands (64%), followed by H/N exc MSG regions (27%), broncho-pulmonary regions, and "others", thus non-salivary gland origins accounted for 9% of all cases. Patients with SDC, MEC, AcCC, or SGTC of the major salivary glands and broncho-pulmonary regions were more frequently treated by surgery. The overall survival time of the patients with MEC was significantly better than that of patients with SDC or EMC. CONCLUSIONS: This cross-organ study highlights the clinical significance of SGTCs, underscoring the need for developing novel therapies for this rare disease entity.

Prognostic value of tumor volume doubling time in lung-metastatic adenoid cystic carcinoma.

OBJECTIVES: Lung metastases in adenoid cystic carcinoma (ACC) usually have indolent growth and the optimal timing to start systemic therapy is not established. We assessed ACC lung metastasis tumor growth dynamics and compared the prognostic value of time to progression (TTP) and tumor volume doubling time (TVDT). METHODS: The study included ACC patients with ≥1 pulmonary metastasis (≥5 mm) and at least 2 chest computed tomography scans. Radiology assessment was performed from the first scan showing metastasis until treatment initiation or death. Up to 5 lung nodules per patient were segmented for TVDT calculation. To assess tumor growth rate (TGR), the correlation coefficient (r) and coefficient of determination (R2) were calculated for measured lung nodules. TTP was assessed per RECIST 1.1; TVDT was calculated using the Schwartz formula. Overall survival was analyzed using the Kaplan-Meier method. RESULTS: The study included 75 patients. Sixty-seven patients (89%) had lung-only metastasis on first CT scan. The TGR was overall constant (median R2 = 0.974). Median TTP and TVDT were 11.2 months and 7.5 months. Shorter TVDT (<6 months) was associated with poor overall survival (HR = 0.48; p = 0.037), but TTP was not associated with survival (HR = 1.02; p = 0.96). Cox regression showed that TVDT but not TTP significantly correlated with OS. TVDT calculated using estimated tumor volume correlated with TVDT obtained by segmentation. CONCLUSION: Most ACC lung metastases have a constant TGR. TVDT may be a better prognostic indicator than TTP in lung-metastatic ACC. TVDT can be estimated by single longitudinal measurement in clinical practice.

Omission of radiotherapy to lymph node level III in patients with cN0 adenoid cystic carcinoma of the major salivary gland: a single center experience.

PURPOSE: Due to the rarity of adenoid cystic carcinoma (ACC) of the major salivary gland, there is no consensus on the extent of prophylactic neck irradiation (PNI) for patients with clinically negative lymph nodes (cN0) disease. MATERIALS AND METHODS: We conducted a retrospective analysis of all patients with ACC of the major salivary gland who received treatment at our center between January 2010 and April 2020. The primary endpoint was regional failure-free survival (RRFS). Secondary endpoints included overall survival (OS), distant metastasis-free survival (DMFS), local recurrence-free survival (LRFS), and acute toxicity. RESULTS: A total of 139 patients were included in the analysis. For cN0 patients, the 5-year RRFS, OS, DMFS, and LRFS were 93.2%, 90.2%, 75.7%, and 91.4%, respectively. Multivariate analysis revealed that PORT was an independent prognostic factor for RRFS and LRFS. No statistically significant differences were observed between the Level III sparing PNI group and the Standard PNI group in terms of RRFS, OS, DMFS, and LRFS. The doses delivered to the larynx and thyroid in the Level III sparing PNI group were significantly lower than those in the Standard PNI group. CONCLUSION: In patients with cN0 ACC of the major salivary gland, PNI improves regional control, and the level III nodal region sparing radiotherapy does not increase the risk of level III recurrence, while potentially reducing toxicity.