Mucoepidermoid Carcinoma of the Parotid: Very Close Margins and Adjuvant Radiotherapy

Comparison of Partial Versus Superficial or Total Parotidectomy for Superficial T1-2 Primary Parotid Cancers

OBJECTIVES

This study aimed to compare the oncological outcomes of partial versus superficial or total parotidectomy for superficial T1 or T2 primary parotid cancers and investigate their prognostic factors and recurrence patterns.

METHODS

The medical records of 77 patients with T1-2 primary parotid malignancies between May 2003 and March 2022 were retrospectively reviewed. Univariate and multivariate analyses were performed to evaluate the prognostic factors associated with overall survival, disease-free survival, and local and distant recurrence.

RESULTS

The average follow-up duration was 70.2 months (range, 12-202 months). The 5-year overall and disease-free survival rates were 88.7% and 77.1%, respectively. Twenty-two patients underwent partial parotidectomy, and 55 underwent superficial or total parotidectomy. There were no significant differences in the disease recurrence (P=0.320) and mortality rates (P=0.884) of the partial and superficial or total parotidectomy groups. The mean duration of surgery was shorter and the overall complication rates were significantly lower in the partial group than in the superficial or total parotidectomy group (P=0.049). Sixteen cases of recurrence occurred during the study period (20.8%). Univariate analyses showed that high-grade tumors (P=0.006), lymphovascular invasion (P=0.046), and regional lymph node metastasis (P=0.010) were significant risk factors for disease recurrence. Multivariate analysis identified regional lymph node metastasis as an independent prognostic factor for disease recurrence (P=0.027), and lymphovascular invasion as an independent prognostic factor for overall survival (P=0.033).

CONCLUSION

The conservative surgical approach of partial parotidectomy can yield oncological outcomes comparable to those of superficial or total parotidectomy with careful patient selection in T1-2 parotid cancers.

Oncologic Safety of Close Margins in Patients With Low- to Intermediate-Grade Major Salivary Gland Carcinoma

Importance

Postoperative radiation therapy for close surgical margins in low- to intermediate-grade salivary carcinomas lacks multi-institutional supportive evidence.

Objective

To evaluate the oncologic outcomes for low- and intermediate-grade salivary carcinomas with close and positive margins.

Design, Setting, and Participants

The American Head and Neck Society Salivary Gland Section conducted a retrospective cohort study from 2010 to 2019 at 41 centers. Margins were classified as R0 (negative), R1 (microscopically positive), or R2 (macroscopically positive). R0 margins were subclassified into clear (>1 mm) or close (≤1 mm). Data analysis was performed from June to October 2023.

Main Outcomes and Measures

Main outcomes were risk factors for local recurrence.

Results

A total of 865 patients (median [IQR] age at surgery, 56 [43-66] years; 553 female individuals [64%] and 312 male individuals [36%]) were included. Of these, 801 (93%) had parotid carcinoma and 64 (7%) had submandibular gland carcinoma, and 748 (86%) had low-grade tumors and 117 (14%) had intermediate-grade tumors, with the following surgical margins: R0 in 673 (78%), R1 in 168 (19%), and R2 in 24 (3%). Close margins were found in 395 of 499 patients with R0 margins (79%), for whom margin distances were measured. A total of 305 patients (35%) underwent postoperative radiation therapy. Of all 865 patients, 35 (4%) had local recurrence with a median (IQR) follow-up of 35.3 (13.9-59.1) months. In patients with close margins as the sole risk factor for recurrence, the local recurrence rates were similar between those who underwent postoperative radiation therapy (0 of 46) or observation (4 of 165 [2%]). Patients with clear margins (n = 104) had no recurrences. The local recurrence rate in patients with R1 or R2 margins was better in those irradiated (2 of 128 [2%]) compared to observed (13 of 64 [20%]) (hazard ratio [HR], 0.05; 95% CI, 0.01-0.24). Multivariable analysis for local recurrence found the following independent factors: age at diagnosis (HR for a 10-year increase in age, 1.33; 95% CI, 1.06-1.67), R1 vs R0 (HR, 5.21; 95% CI, 2.58-10.54), lymphovascular invasion (HR, 4.47; 95% CI, 1.43-13.99), and postoperative radiation therapy (HR, 0.10; 95% CI, 0.04-0.29). The 3-year local recurrence-free survivals for the study population were 96% vs 97% in the close margin group.

Conclusions and Relevance

In this cohort study of patients with low- and intermediate-grade major salivary gland carcinoma, postoperative radiation therapy for positive margins was associated with decreased risk of local recurrence. In isolation from other risk factors for local recurrence, select patients with close surgical margins (≤1 mm) may safely be considered for observation.

Milan system for reporting salivary gland cytology in diagnosis and surgery of parotid gland lesions

INTRODUCTION

A cytology report is always a challenge for both head and neck surgeons and cytopathologists to diagnose and manage parotid gland (PG) diseases, because of the various similar features between the lesions.

OBJECTIVES

The present study was conducted to assess our practice using the Milan System for Reporting Salivary Cytopathology (MSRSGC) and to evaluate the risk of malignancy (ROM) in different categories.

PATIENTS AND METHODS

The patients with parotid gland lesions were diagnosed by clinical examination, ultrasound, and FNAC under ultrasound guidance at our hospital from 1 May 2019 to 30 April 2021. The FNAC results were divided into six categories according to the Milan system. We calculated the ROM for each category of the Milan system based on histopathological follow-up.

RESULTS

This study included 204 patients. There were 115 men (56 %) aged 46-60 years. Pathology results were 33 cases for malignant and 182 cases for benign. The rate of malignancy for each category according to the MSRSGC were 23.1 % (non-neoplastic), 20 % (atypical), 50 % (neoplastic), 1 % (benign), 10.3 % (salivary neoplasm of uncertain neoplastic potential), 84.6 % (suspicious for malignancy), and 100 % (malignant) categories. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of FNAC with application of Milan system were respectively 90.9 %, 98.2 %, 90.9 %, 98.9 % and 97 %.

CONCLUSION

When the Milan system was applied, FNAC had a high efficacy, suggesting that MSRSGC can improve the communication between the cytopathologist and the surgeon. This system can allow the surgeon to decide the extent of the surgery.

Limited parotid surgery as sole form of treatment for carefully selected malignant tumours of the parotid gland: Still sufficient on the long-term?

BACKGROUND

The aim of the study was to investigate the oncological and functional outcome following extracapsular dissection as the sole form of treatment in locally limited low-grade malignant parotid tumours in the long term.

METHODS

The records of all patients treated for T1-T2 low-grade malignant tumours of the parotid gland solely by means of extracapsular dissection between 2005 and 2017 were studied retrospectively.

RESULTS

A total of 16 cases formed our study sample (7 men, 9 women). Their mean age was 50.2 years (21-84 years). Mean follow-up was 107 months (60-201 months). In 6 cases the tumour was an acinic cell carcinoma, in 9 cases a mucoepidermoid carcinoma and in one case a basal cell adenocarcinoma. Regarding the T category, the tumour was Tis in one case, T1 in 12 cases and T2 in three cases. The five-year disease-specific survival rate was 100 %, as was local disease control. Facial nerve function was House-Brackmann grade I without exception.

CONCLUSIONS

Our study showed very encouraging long-term results following primary extracapsular dissection as the sole surgical therapy for carefully selected low-stage, low-grade, inferiorly located lesions in patients with high compliance.

LAY SUMMARY

The "one-size-fits-all" strategy of complete parotidectomy with neck dissection might be tantamount to overtreatment by less aggressive cases of parotid cancer. Extracapsular dissection seems to be oncologically sufficient for carefully selected T1-T2 low-grade cases in the long-term in patients with ensured follow-up.

Presentation and outcomes of patients with clinically T1-2, N0 parotid mucoepidermoid carcinoma: The roles of elective neck dissection and adjuvant radiotherapy

Objectives

Examine the role of elective neck dissection (END) and adjuvant radiotherapy (RT) in early‐stage clinically N0 parotid mucoepidermoid carcinoma (MEC).

Methods

The study is a retrospective analysis of the National Cancer Database, 2004–2016. The study population included adult patients with MEC who underwent parotidectomy.

Results

A total of 1233 patients were included. Histopathology demonstrated well, moderately, and poorly differentiated MEC 47.12%, 39.98%, and 12.90% of the time, respectively. END was performed in 78.67% of patients, resulting in nodal upstaging in 4.43% and identification of extracapsular extension (ECE) in 0.72%. RT was utilized in 67.33% of patients with advanced pathological features. Neither END nor RT improved overall survival separately (p < 0.05) or combined (adjusted HR: 1.19, 95%CI: 0.52, 2.70, p = 0.68).

Conclusion

This study provides an epidemiological perspective regarding patients with clinically T1‐2, N0 MEC. There was no observed survival advantage with END and RT.

[Surgery for parotid gland cancer-controversial and proven aspects]

BACKGROUND

Due to the rarity of primary parotid malignancies, there are currently only limited clinical study data on the optimal surgical therapy. Parotid malignancies encompass a broad spectrum of more than 20 different histological subtypes with varying biology, which thus represents a challenge for even experienced pathologists and head and neck surgeons with proven expertise in salivary gland surgery.

OBJECTIVE

The aim of this review article is to provide an overview of the current literature on surgical therapy of the primary tumor and the cN0 neck as well as treatment of the facial nerve, and to shed light on the various controversial aspects of this topic.

RESULTS

In salivary gland oncology there is a trend towards safe (R0) but more conservative surgery. Currently, less-invasive surgical approaches could potentially be applied in a small subgroup with carefully selected caudally located and R0-resected "low-grade tumors" in stages T1-T2 and cN0 in relatively young patients with high compliance and more in the context of structured clinical studies. Elective neck dissection in the case of cN0 status should be carried out if risk factors for occult cervical lymph node metastasis (T3-T4a, "high-grade subtypes," advanced age, lymphangitic carcinomatosis) are present. In cases of small "low-grade parotid carcinomas," narrow resection margins or even microscopic tumor residues on the facial nerve can potentially be adequately compensated with adjuvant radiation therapy. However, due to the lack of solid data, the significance of the actual effect of the radiation in this situation should be viewed with great caution.

Intraosseous mucoepidermoid carcinoma of mandible: a rare case presentation and literature review

Intraosseous mucoepidermoid carcinoma (IMC) is an atypical salivary gland neoplasm commonly seen in middle-aged adults. Their presentation in young individuals below the age group of 20 years is sporadic. Treatment modality mainly includes radical surgical resection for malignant tumours. There were only 13 reported cases of IMC of mandible below the age of 20 years in the English literature. All the reported cases were only managed with wide resection and radiotherapy. Surgical resection leads to loss of form and function in the young population, decreasing their morale. Hence, reconstruction should be mandated in young individuals for restoring function and aesthetics. We present a case of IMC of the mandible in a young female individual resected and reconstructed with a free fibula bone graft. Satisfactory healing is elicited with no recurrence at the 2-year follow-up period.

Metastatic mucoepidermoid carcinoma to the pleura: a case report

BACKGROUND

Mucoepidermoid carcinoma is the most common malignant neoplasm arising from the salivary glands (Ali et al. in J Ayub Med Coll Abbottabad 20(2): 141-2, 2008, Xi et al. in World J Surg Oncol 10: 232, 2012). When arising from anatomic sites other than the salivary glands it can be a diagnostic challenge. Primary and metastatic mucoepidermoid carcinoma from and to the pleura are extremely rare entities that are frequently misdiagnosed as adenocarcinoma, adenosquamous carcinoma, or squamous cell carcinoma (Xi et al. in World J Surg Oncol 10: 232, 2012).

CASE PRESENTATION

We describe an unusual case of a 64-year-old Caucasian female patient with metastatic high-grade mucoepidermoid carcinoma to the pleura, morphologically resembling squamous cell carcinoma. Molecular studies of both the parotid gland and pleural tumors helped prove the metastatic nature of the pleural lesion.

CONCLUSIONS

 Metastatic mucoepidermoid carcinoma to the pleura is a rare entity, frequently misdiagnosed as squamous cell carcinoma. Differentiating between a lung primary and a metastatic disease has treatment implications and prognostic significance for the patient. When morphologic and immunophenotypic overlap exists, molecular testing can help distinguish mucoepidermoid carcinoma from other neoplasms.

Evaluation of Surgical Margin Status in Patients With Salivary Gland Cancer

Importance

Salivary gland cancer comprises a diverse group of histologic types with different biological behavior. Owing to this heterogeneity, the association of margin status and postoperative adjuvant radiotherapy has been poorly studied.

Objective

To examine the association between surgical margin status and oncologic outcomes and the subsequent outcome of adjuvant radiotherapy in patients with salivary gland carcinomas.

Design, Setting, and Participants

This cohort study analyzed data from institutional records at Memorial Sloan Kettering Cancer Center from 1985 to 2015. Statistical analysis was completed on October 31, 2020. After exclusions, 837 patients with surgically treated salivary gland carcinoma were identified. Surgical margins and histologic characteristics identified from pathology reports were recorded, with margins classified as negative, close, and positive, and individual histologic types classified into 3 risk groups: low, intermediate, and high.

Exposures

The outcome of adjuvant radiotherapy was determined in patients with close margins with low- and intermediate-risk histologic type and overall pathologic stage I/II disease.

Main Outcomes and Measures

Disease-specific survival (DSS) and local recurrence-free survival (LRFS) outcomes were calculated using the Kaplan-Meier method. Multivariable analysis was performed using the Cox proportional hazards regression model. A planned subgroup analysis of patients with close margins was conducted.

Results

Among the 837 patients identified, 438 were women (52.3%); median age at surgery was 58 years (range, 6-98). A total of 399 tumors (47.7%) originated from major salivary glands, and 438 (52.3%) from minor salivary glands. Margin positivity rates were not different between minor and major salivary gland tumors. Positive surgical margins were identified in 252 patients (30.1%), with nasal cavity/paranasal sinuses and trachea/larynx subsites as the most common sites. Close margins were recorded in 203 patients (24.3%). Adjuvant radiotherapy was administered in 80.5% (103 of 128) of patients with major salivary gland cancer with positive margins, 58.8% (60 of 102) with close margins, and 30.7% (52 of 169) with negative margins and in 70.2% (87 of 124), 36.6% (37 of 101) , and 19.7% (42 of 213) patients with minor salivary gland cancer. With median follow up time of 57 months (range, 1-363 months), patients with positive margins had poorer DSS and LRFS. However, after controlling for overall stage, histologic risk group, and adjuvant radiotherapy, margin status was not a factor associated with poorer DSS or LRFS. In patients with close margins, low-risk and intermediate-risk histologic type, and overall pathologic stage I/II, patients who did not have adjuvant radiotherapy had comparable local control with those who received adjuvant radiotherapy.

Conclusions and Relevance

The findings of this cohort study suggest that patients with salivary gland cancer who have either close or positive surgical margins are at increased risk for poorer local control and survival. After controlling for tumor stage, histologic risk group, and the use of adjuvant radiotherapy, margin status was not an independent factor associated with poorer outcome. Subgroup analyses showed that care for patients with close margins with low-risk or intermediate-risk histologic type who have stage I/II cancers might be managed safely without adjuvant radiotherapy.

Management of Salivary Gland Malignancy: ASCO Guideline

PURPOSE

To provide evidence-based recommendations for practicing physicians and other healthcare providers on the management of salivary gland malignancy.

METHODS

ASCO convened an Expert Panel of medical oncology, surgical oncology, radiation oncology, neuroradiology, pathology, and patient advocacy experts to conduct a literature search, which included systematic reviews, meta-analyses, randomized controlled trials, and prospective and retrospective comparative observational studies published from 2000 through 2020. Outcomes of interest included survival, diagnostic accuracy, disease recurrence, and quality of life. Expert Panel members used available evidence and informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 293 relevant studies to inform the evidence base for this guideline. Six main clinical questions were addressed, which included subquestions on preoperative evaluations, surgical diagnostic and therapeutic procedures, appropriate radiotherapy techniques, the role of systemic therapy, and follow-up evaluations.

RECOMMENDATIONS

When possible, evidence-based recommendations were developed to address the diagnosis and appropriate preoperative evaluations for patients with a salivary gland malignancy, therapeutic procedures, and appropriate treatment options in various salivary gland histologies.Additional information is available at www.asco.org/head-neck-cancer-guidelines.

Overall and cause-specific survival for mucoepidermoid carcinoma of the major salivary glands: Analysis of 2210 patients

BACKGROUND

Mucoepidermoid carcinoma (MEC) is a rare malignancy of the head and neck; however, it accounts for a majority of the tumors of the salivary glands. This study used a national population-based registry to describe the pre-treatment and treatment-related prognostic factors that influence survival in patients with MEC of the major salivary glands. To our knowledge, this is the largest population-based study examining predictors of both overall and cause-specific survival of MEC of the major salivary glands.

AIM

To identify prognostic factors influencing overall survival (OS) and cause-specific survival (CSS) of patients with MEC of the major salivary glands.

METHODS

We used the Surveillance, Epidemiology and End-Results Database of the National Cancer Institute to investigate a variety of factors that could influence survival of patients diagnosed with mucoepidermoid carcinoma of the major salivary glands. A total of 2210 patients diagnosed with MEC of the major salivary glands during the years of 1975-2016 were studied. The primary endpoints were OS and CSS. Cox regression analysis was used to perform univariate and multivariate analyses of clinical variables such as age at diagnosis, diagnosis year, sex, race, tumor size, stage, grade, treatment with or without surgical excision, and adjuvant radiotherapy treatment.

RESULTS

A total of 2210 patients diagnosed with MEC of the major salivary glands met inclusion criteria. In this study, 95% of patients underwent surgical excision and 41% received adjuvant radiation therapy. Median OS time for Grade I, II, and III/IV was 401 mo (± 48.25, 95%CI), 340 mo (± 33.68, 95%CI) and 55 mo (± 11.05, 95%CI), respectively. Univariate analysis revealed that lack of surgical excision was associated with decreased OS [hazard ratio (HR) 4.26, P < 0.0001] and that patients with localized disease had improved OS compared to both regional and distant disease (HR 3.07 and 6.96, respectively, P < 0.0001). Additionally, univariate analysis demonstrated that male sex, age over 50 at diagnosis, Grade III tumors, and increasing tumor size were associated with worsened OS (P < 0.0006). Univariate analysis of CSS similarly revealed that lack of surgical excision and Grade III carcinoma conferred decreased CSS (HR 4.37 and 5.44, respectively, P < 0.0001). Multivariate analysis confirmed that increasing age, in 10-year age bands, advanced tumor stage, increasing tumor size, Grade III carcinoma, male sex, and lack of surgical excision were associated with a statistically significant decrease in OS and CSS (P < 0.04). Of note, multivariate analysis revealed that the use of adjuvant radiation therapy was not associated with improved OS or CSS.

CONCLUSION

Multivariate analysis demonstrated increasing age, advanced tumor stage, increasing tumor size, Grade III carcinoma, male sex, and lack of surgical excision were associated with decreased OS and CSS (P < 0.04).

Prognostic factors in mucoepidermoid carcinoma of the minor salivary glands: A single-center retrospective study

OBJECTIVE

The objective of this study was to investigate the prognostic effects of clinical and histologic findings in patients with mucoepidermoid carcinoma (MEC) of minor salivary glands.

STUDY DESIGN

This retrospective clinical review included 63 patients (30 males, mean age 52.8 years) with minor salivary gland MEC treated at our hospital from 1994 to 2019. Overall survival (OS) or disease-free survival was determined using the Kaplan-Meier limit method. Correlations between different factors and survival rates were assessed using chi-square tests.

RESULTS

The 10-year OS rate was 91.2%. Low- or intermediate-grade MEC had a good prognosis regardless of the surgical margin, whereas high-grade MEC had a poor 10-year OS rate (64.2%). Ten patients developed recurrence or metastasis after primary surgical resection, of whom 6 were diagnosed with a high-grade tumor. The most frequently affected site was the palate, whereas the mandibular gingiva was the most commonly affected site during recurrence. Of 4 patients who received chemotherapy and/or radiotherapy postsurgery, 2 had local recurrence and/or neck lymph node metastasis and 1 died from MEC.

CONCLUSION

Patients with low- or intermediate-grade MEC exhibited satisfactory survival after surgery. In patients with high-grade tumors, it has been suggested that survival rates are poor and do not improve following adjuvant therapy.

Efficacy of surgery combined with postoperative 125 I interstitial brachytherapy for treatment of acinic cell carcinoma of the parotid gland in children and adolescents

BACKGROUND

Acinic cell carcinoma (AciCC) is rare in children; therefore, reaching a consensus on its management is challenging and radiotherapy is limited by concerns about long-term toxicity. The purpose of this study is to analyze the effectiveness and safety of surgery plus postoperative ¹²⁵ I interstitial brachytherapy (IBT) for children and adolescents with AciCC of the parotid gland (PG) treated at a single institution.

PROCEDURE

Sixteen patients ≤ 18 years old with AciCC of the PG treated with surgery plus ¹²⁵ I IBT from 2007 to 2018 were included. Surgery was the primary treatment; ten patients underwent total gross excision and six subtotal gross excision. The matched peripheral dose was 60-120 Gy. Overall survival, disease-free survival (DFS), local control rate, distant metastasis, and radiation-associated toxicities were analyzed, and factors influencing outcomes were evaluated.

RESULTS

During follow-up (1.8-12.6 years; mean, 6.3 years), lymph node metastasis was observed in one case, 2.6 years after ¹²⁵ I IBT treatment. The five-year overall and DFS rates were 100% and 91.7%, respectively. On univariate analysis, tumor size ≥ 3 cm (100% vs 50%; P = 0.025) and extraglandular extension (100% vs 50%; P = 0.025) were significant prognostic indicators for DFS. No severe radiation-associated complications occurred.

CONCLUSIONS

Children and adolescents with AciCC of the PG with high-risk features can be managed using surgery plus postoperative ¹²⁵ I IBT with excellent local control. Radiation-related complications were minor. Patients with facial nerve involvement can have their facial nerves preserved. Residual tumors can be safely managed using adjuvant ¹²⁵ I IBT.

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.

Nomogram to predict the prognosis of parotid gland mucoepidermoid carcinoma: a population-based study of 1306 cases

Background

Mucoepidermoid carcinoma (MEC) is a common cancer in the oral salivary gland malignancy, which mainly occurs in the parotid gland. The aim of this study is to identify independent prognostic factors and establish a nomogram model for parotid gland mucoepidermoid carcinoma (P-MEC) patients using the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database.

Method

Patients with P-MEC were selected from between 2004 and 2015. The overall survival (OS) and cancer-specific survival (CSS) rates were estimated using the Kaplan-Meier method with the log-rank test. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify the independent prognostic factors.

Results

A total of 1,306 patients with P-MEC were enrolled. Age, grade, T stage, N stage, M stage, chemotherapy, and surgery type were independent prognostic factors for OS and CSS. A nomogram for OS was formulated based on these independent prognostic factors and validated using an internal bootstrap resampling approach, which showed that the nomogram exhibited a sufficient level of discrimination according to the C-index (0.877, 95% CI [0.855–0.898]).

Conclusion

Several prognostic factors for P-MEC were identified. The nomogram developed in this study accurately predicted the 5- and 10-year OS rates of American patients with P-MEC based on individual characteristics. Risk stratification using the survival nomogram can optimize individual therapies and follow-up.