Advanced small cell carcinoma of the uterine cervix treated by neoadjuvant chemotherapy with irinotecan and cisplatin followed by radical surgery

Small-cell neuroendocrine carcinoma of the female genital tract: A comprehensive overview

Small-cell neuroendocrine carcinomas (SCNECs) of the female genital tract are rare and aggressive tumors that are characterized by a high rate of recurrence and poor prognosis. They can arise from various sites within the female genital tract, including the cervix, endometrium, ovary, fallopian tube, vagina, and vulva. They are composed of cells with neuroendocrine features, such as the ability to produce and secrete hormones and peptides, and a high mitotic rate. Immunohistochemical staining for neuroendocrine markers, such as chromogranin A, synaptophysin, and CD56, can aid in the diagnosis of these tumors. This article provides an overview of the epidemiology, etiology, and risk factors associated with these tumors, as well as their clinical presentation, cellular characteristics, diagnosis, and finally the current treatment options for SCNECs, including surgery, chemotherapy, and radiation therapy, alone or in combination.

In-silico analysis reveals Quinic acid as a multitargeted inhibitor against Cervical Cancer

The cervix is the lowermost part of the uterus that connects to the vagina, and cervical cancer is a malignant cervix tumour. One of this cancer's most important risk factors is HPV infection. In the approach to finding an effective treatment for this disease, various works have been done around genomics and drug discovery. Finding the major altered genes was one of the most significant studies completed in the field of cervical cancer by TCGA (The Cancer Genome Atlas), and these genes are TGFBR2, MED1, ERBB3, CASP8, and HLA-A. The greatest genomic alterations were found in the PI3K/MAPK and TGF-Beta signalling pathways, suggesting that numerous therapeutic targets may come from these pathways in the future. We, therefore, conducted a combined enrichment analysis of genes gathered from various works of literature for this study. The final six key genes from the list were obtained after enrichment analysis using GO, KEGG, and Reactome methods. The six proteins against the identified genes were then subjected to a docking-based screening against a library of 6,87,843 prepared natural compounds from the ZINC15 database. The most stable compound was subsequently discovered through virtual screening to be the natural substance Quinic acid, which also had the highest binding affinity for all six proteins and a better docking score. To examine their stability, the study was extended to MM/GBSA and MD simulations on the six docked proteins, and comparative docking-based calculations led us to identify the Quinic Acid as a multitargeted compound. The overall deviation of the compound was less than 2 Å for all the complexes considered best for the biological molecules, and the simulation interaction analysis reveals a huge web of interaction during the simulation.Communicated by Ramaswamy H. Sarma.

Expert Consensus Practice Recommendations of the North American Neuroendocrine Tumor Society for the management of high grade gastroenteropancreatic and gynecologic neuroendocrine neoplasms

High-grade neuroendocrine neoplasms are a rare disease entity and account for approximately 10% of all neuroendocrine neoplasms. Because of their rarity, there is an overall lack of prospectively collected data available to advise practitioners as to how best to manage these patients. As a result, best practices are largely based on expert opinion. Recently, a distinction was made between well-differentiated high-grade (G3) neuroendocrine tumors and poorly differentiated neuroendocrine carcinomas, and with this, pathologic details, appropriate imaging practices and treatment have become more complex. In an effort to provide practitioners with the best guidance for the management of patients with high-grade neuroendocrine neoplasms of the gastrointestinal tract, pancreas, and gynecologic system, the North American Neuroendocrine Tumor Society convened a panel of experts to develop a set of recommendations and a treatment algorithm that may be used by practitioners for the care of these patients. Here, we provide consensus recommendations from the panel on pathology, imaging practices, management of localized disease, management of metastatic disease and surveillance and draw key distinctions as to the approach that should be utilized in patients with well-differentiated G3 neuroendocrine tumors vs poorly differentiated neuroendocrine carcinomas.

Neuroendocrine Carcinoma of Cervix: A Case Series

Cervical cancer is the second most common cause of cancer-related mortality in women globally. Neuroendocrine carcinomas are among the rarest and least studied histopathological types of cervical cancers, accounting for 1.4% of all cervical cancers. Neuroendocrine carcinomas of the cervix (NECCs) are aggressive tumors that can be associated with several high-risk features such as early lymphovascular invasion and multiple systemic metastases, at early stages. Here, we present a case series of five patients with NECC who have been diagnosed and managed at a tertiary care hospital in coastal Andhra Pradesh, South India. Using the hospital records, we made a list of patients with NECC who were diagnosed by histopathological findings between 2019 and 2022. Details regarding their demographic variables, presenting complaints, staging, and treatment given were noted down using a pre-defined proforma.

PD-L1, PARP1, and MMRs as potential therapeutic biomarkers for neuroendocrine cervical cancer

Objective

Neuroendocrine cervical cancer (NECC) is a rare cervical cancer with high aggressivity that causes poor prognosis even in the early stage. Given other neuroendocrine carcinomas and other types of cervical cancer have been proved to have expression of programmed cell death protein 1 ligand 1(PD‐L1) and poly ADP‐ribose polymerase‐1(PARP1), we would measure and analyze these proteins in this invasive cancer. The purpose of this study is to investigate the application value of PD‐1/PD‐L1 and PARP1 inhibitors in NECC.

Methods

The NECC cases in our center with formalin‐fixed paraffin‐embedded tissue blocks were collected, and immunohistochemical (IHC) staining of PD‐L1, PARP1, Mismatch repair proteins (MMRs), and P53 was performed. Chi‐square test was used to analyze associations between various protein expressions. We analyzed the efficacy of immunotherapy in a recent patient with secondary recurrence after two courses of chemotherapy.

Results

After rigorous screening, 20 cases were finally included. Three cases did not undergo surgical treatment because of their advanced stage. Twelve (60%) developed distant metastases or relapsed within five years, and most of them within two years. The positive rate of PD‐L1 and PARP1 were 70% and 75% respectively. Among all the cases, microsatellite instability (MSI) was seen in six cases (30%) and abnormal p53 expression was in 15 patients (75%). PD‐L1 was associated with PARP1 expression in the MSI subgroup. The patient treated with chemotherapy + VEGF inhibitor (VEGFi) + programmed cell death protein 1(PD‐1) inhibitor had an excellent improvement in clinical symptoms, tumor markers, and mass size.

Conclusion

The IHC results of PD‐L1, PARP1, and MMRs suggested that NECC was the target of immunotargeted therapy. Our case confirmed that immune checkpoint therapy was effective in patients with PD‐L1 positive and MMRs loss. Considering the clinical practicability, more cases should be collected, and effective biomarkers still need to be further searched.

Heterogenous chemosensitivity of a panel of organoid lines derived from small cell neuroendocrine carcinoma of the uterine cervix

Small cell neuroendocrine carcinoma (SCNEC) of the uterine cervix is a rare disease with a poor prognosis. The lack of established disease models has hampered therapy development. We generated a panel of cancer tissue-originated spheroid (CTOS) lines derived from SCNEC of the uterine cervix using a method based upon cell-cell contact throughout the preparation and culturing processes. Using 11 CTOS lines, we assessed the sensitivity of various drugs used in clinical practice. Drug sensitivity assays revealed significant heterogeneous inter-CTOS chemosensitivity. Microarray analyses were then performed to identify sensitivity-related gene signatures. Specific gene sets were identified which likely contribute to the sensitivity to the tested drugs. We identified a line (Cerv54) that was exceptionally sensitive to irinotecan. Cerv54 had increased levels of CES1, which catalyzes the conversion of irinotecan to the active form, SN38, although in Cerv54 cells, SN38 was undetectable, CES1 expression and activity were markedly low compared to the liver, and a CES1 inhibitor had no effect on irinotecan sensitivity. These results suggested a novel irinotecan mode of action in Cerv54. Our CTOS lines may be useful for understanding the variation and mechanism of drug sensitivity, contributing to the understanding and development of chemotherapeutic drugs.

Prognostic factors and outcomes of early-stage small cell neuroendocrine carcinoma of the cervix: 37 cases from a single center

Background

The objective of this study is to investigate small cell neuroendocrine carcinoma of the cervix (SCCC), using a retrospective clinicopathological characteristic and treatment approach.

Method

We retrospectively analyzed cases of early-stage SCCC, identified between 2006 and 2016, in women who received radical surgery and adjuvant chemotherapy with or without radiotherapy. Kaplan–Meier and one-way ANOVA analyses were performed.

Result

A total of 37 cases of SCCC are presented in this study, of which 21 had stage IB1 SCCC, 12 had stage IB2, 3 had stage IIA1, and 1 had stage IIA2. All patients were treated with radical surgery and adjuvant chemotherapy, specifically, 26 with radical surgery followed by adjuvant chemotherapy plus radiation and 11 with neoadjuvant chemotherapy (NACT) followed by radical surgery. After a median follow-up time of 27 months (range, 8–115 months), the 2-year and 5-year disease-free survival rate for all patients was 51.9% and 34.1%, respectively, and the overall survival rate was 60.3% and 38.6%, respectively. Univariate analysis showed that International Federation of Gynecology and Obstetrics (FIGO) stage and tumor size may be a predictor of a poor prognosis. NACT and adjuvant radiation did not improve survival over adjuvant chemotherapy alone but should not be a significant independent prognostic factor for survival.

Conclusion

Even in patients with early-stage SCCC, the prognosis is poor, although FIGO stage and tumor size may act as surrogate factors prognostic of survival.

PD-L1, RB1 and mismatch repair protein immunohistochemical expression in neuroendocrine carcinoma, small cell type, of the uterine cervix

AIMS

Neuroendocrine carcinoma, small cell type, of the uterine cervix (SmCC-Cx) is a rare human papilloma virus (HPV) related tumour with limited therapeutic options. Merkel cell carcinoma, another virus-associated neuroendocrine malignancy, has significant programmed death ligand 1 (PD-L1) expression rates. PD-L1 expression has been reported in other malignancies of the cervix. We aimed to determine the prevalence of PD-L1 in the context of mismatch repair protein (MMR) and RB1 expression status in SmCC-Cx.

METHODS AND RESULTS

Ten cases of SmCC-Cx were tested by immunohistochemistry for expression of PD-L1, MLH1, MSH2, MSH6, PMS2, RB1, CD3, CD20 and for HPV by in-situ hybridisation (ISH). PD-L1 expression was scored quantitatively (H-score) in tumour cells and lymphocytes (tumoral/peritumoral). PD-L1 positivity was seen in seven cases, focal in most (H-score range 3-140). Three of nine cases showed MMR deficiency. PD-L1 expression levels correlated with MMR expression status: all three MLH1/PMS2-deficient cases had a ≥5% PD-L1 staining and an H-score ≥10 (P = 0.01). RB1 was lost in four of nine cases, all PD-L1 positive, but this correlation was not statistically significant. Seven of nine tumours were positive for HPV-ISH; two of these had MLH1/PMS2 loss. Of the two HPV-ISH negative tumours, one had MLS1/PMS2 loss.

CONCLUSIONS

PD-L1 expression, predominantly focal, is seen in 70% of SmCC-Cx, while loss of MMR expression is seen in 33% of SmCC-Cx in our cohort. PD-L1 expression in more than 10% of tumour cells is seen in a subset of tumours in association with loss of MMR expression. These patients may be amenable to immune checkpoint inhibitor therapy as a promising alternative for this aggressive disease.

Synchronous endometrioid carcinoma of the endometrium and small cell neuroendocrine carcinoma of the cervix: a rare combination

Synchronous multiple primaries of female genital tract are uncommon, with the most frequently encountered combination being of endometrium and ovary. Concurrent primary tumours of endometrium and cervix are rare. We report a case of coexistent endometrioid carcinoma of the endometrium and small cell neuroendocrine carcinoma of the cervix in 48-year-old woman who presented with menometrorrhagia and was detected to have metastases to distant sites on imaging. She underwent multimodality treatment which resulted in a significant reduction in the tumour bulk.

Coexisting squamous cell carcinoma and high-grade neuroendocrine carcinoma, small cell type: a rare collision in cervix

Collision tumours of the uterine cervix are extremely uncommon with exact incidence not known. Unlike squamous cell carcinoma (SCC) and adenocarcinoma that are known to coexist, small cell neuroendocrine carcinoma (SCNEC) is rarely documented with other histological types in the cervix. We report such rare case of a collision tumour in cervix displaying dual histological component of SCNEC and SCC in a 36-year-old woman. The case is being presented because of its rarity and represents a unique and hitherto seldom-reported combination of two malignant tumours with distinct and often contrasting epidemiology, histology and prognosis coexisting in the same patient.

Neuroendocrine carcinoma of the cervix: a systematic review of the literature

BACKGROUND

Neuroendocrine carcinoma of the cervix (NECC) is a rare variant of cervical cancer. The prognosis of women with NECC is poor and there is no standardized therapy for this type of malignancy based on controlled trials.

METHODS

We performed a systematic literature search of the databases PubMed and Cochrane Central Register of Controlled Trials to identify clinical trials describing the management and outcome of women with NECC.

RESULTS

Three thousand five hundred thirty-eight cases of NECC in 112 studies were identified. The pooled proportion of NECC among women with cervical cancer was 2303/163470 (1.41%). Small cell NECC, large cell NECC, and other histological subtypes were identified in 80.4, 12.0, and 7.6% of cases, respectively. Early and late stage disease presentation were evenly distributed with 1463 (50.6%) and 1428 (49.4%) cases, respectively. Tumors expressed synaptophysin (424/538 cases; 79%), neuron-specific enolase (196/285 cases; 69%), chromogranin (323/486 cases; 66%), and CD56 (162/267; 61%). The most common primary treatment was radical surgery combined with chemotherapy either as neoadjuvant or adjuvant chemotherapy, described in 42/48 studies. Radiotherapy-based primary treatment schemes in the form of radiotherapy, radiochemotherapy, or radiotherapy with concomitant or followed by chemotherapy were also commonly used (15/48 studies). There is no standard chemotherapy regimen for NECC, but cisplatin/carboplatin and etoposide (EP) was the most commonly used treatment scheme (24/40 studies). Overall, the prognosis of women with NECC was poor with a mean recurrence-free survival of 16 months and a mean overall survival of 40 months. Immune checkpoint inhibitors and targeted agents were reported as being active in three case reports.

CONCLUSION

NECC is a rare variant of cervical cancer with a poor prognosis. Multimodality treatment with radical surgery and neoadjuvant/adjuvant chemotherapy with cisplatin and etoposide with or without radiotherapy is the mainstay of treatment for early stage disease while chemotherapy with cisplatin and etoposide or topotecan, paclitaxel, and bevacizumab is appropriate for women with locally advanced or recurrent NECC. Immune checkpoint inhibitors may be beneficial, but controlled evidence for their efficacy is lacking.

Small-Cell Neuroendocrine Carcinoma of the Cervix Masquerading as a Cervical Fibroid: Report of a rare entity

Primary neuroendocrine tumours of the cervix are extremely rare, with an incidence of only 0.5-1%; as such, these entities can present a clinical and diagnostic challenge. Small-cell neuroendocrine carcinomas of the cervix are highly aggressive tumours that have a tendency to metastasise. We report a 44-year-old woman who presented to the Gynaecology Clinic of the Employees State Insurance Corporation Medical College & Hospital, Faridabad, India, in 2016 with menorrhagia. Based on a clinical examination, she was provisionally diagnosed with a cervical fibroid. However, a biopsy revealed features of a small-cell neuroendocrine carcinoma of the cervix which was subsequently confirmed via immunohistochemistry. An accurate diagnosis of a neuroendocrine carcinoma is vital as it forms the basis for treatment decisions as well as informing predictions for long-term survival.

Influence of clinicopathological characteristics and comprehensive treatment models on the prognosis of small cell carcinoma of the cervix: A systematic review and meta-analysis

Small cell carcinoma of the cervix (SCCC) is a rare primary neuroendocrine cervical carcinoma with a high degree of invasiveness. SCCC is prone to early-stage lymph node and distant metastases and characterized by a poor prognosis. Currently, there is no standard treatment. This study aimed to evaluate the clinicopathological factors and treatment models that influence SCCC prognosis through a systematic review and meta-analysis, to improve the diagnosis and treatment of SCCC. A comprehensive search was performed in multiple medical literature databases to retrieve studies on the clinical prognosis of SCCC published in China and abroad as of March 1, 2017. Twenty cohort studies with 1904 patients were analyzed. Meta-analysis showed statistical significance for the following factors: FIGO staging (hazard ratio [HR] = 2.63, 95% confidence interval [CI]: 2.13–3.24; odds ratio [OR] = 3.72, 95% CI: 2.46–5.62), tumor size (HR = 1.64, 95% CI: 1.25–2.15), parametrial involvement (HR = 2.40, 95% CI: 1.43–4.05), resection margin (HR = 4.09, 95% CI: 2.27–7.39), lymph node metastasis (OR = 2.09, 95% CI: 1.18–3.71), depth of stromal invasion (HR = 1.99, 95% CI: 1.33–2.97), neoadjuvant chemotherapy (HR = 2.06, 95% CI: 1.14–3.73), and adjuvant chemotherapy (HR = 1.63, 95% CI: 1.26–2.12; OR = 1.48, 95% CI: 1.02–2.16). FIGO staging, tumor size, parametrial involvement, resection margin, depth of stromal invasion, and lymph node metastasis can be used as clinicopathological characteristics for the prediction of SCCC prognosis. Neoadjuvant chemotherapy tended to improve prognosis. Our findings suggest that neoadjuvant chemotherapy plus adjuvant chemotherapy may be the preferred strategy. However, adjuvant radiotherapy appeared to cause no significant improvement in prognosis. Therefore, the clinical application of radiotherapy and the relationship between radiotherapy and clinicopathological factors need to be re-examined. The results of this study should be validated and developed in formal, well-designed multicenter clinical trials.

Cervical cancer - does the morphological subtype affect survival rates?

A retrospective population-based observational study using cancer registration data of women diagnosed with invasive cervical cancer between 2006 and 2010, in England, was carried out to explore how different morphological subtypes affect survival rates. Age-standardised net survival rates by morphological subtype are presented alongside with excess mortality modelling accounting for the impact of demographic, diagnostic and tumour factors. The three main morphological subtypes (squamous cell carcinoma (SCC), adenocarcinoma and adenosquamous carcinoma) have similar one-year net survival rates of approximately 85%. After adjusting for other important determinants of survival, there were no differences at five-years amongst the three main morphological subtypes, with unadjusted survival rates of 55-65%. As expected, women presenting with neuroendocrine tumours had a much poorer outcome than other epithelial cervical malignancies, with 1-year survival of up to 55%, five-year survival of 34% and excess mortality rates compared to SCC varying between 1.9 and 5.9. Impact Statement What is already known on this subject: This is the first study on survival by cervical cancer morphological subtype using national cancer data. What the results of this study add: This study uses excess mortality modelling to investigate the effects of the morphological subtypes whilst adjusting the other factors that affect cervical cancer survival such as stage, age and grade. What the implications are of these findings for clinical practice and/or further research: It is known that cervical neuroendocrine tumours have a poor prognosis and this is confirmed by this study. Squamous cell carcinomas (SCC), adenocarcinomas (AC) and adenosquamous carcinomas (ASC) have the highest net survival and when accounting for other factors there are no differences amongst these morphological subtypes in terms of survival.

Neuroendrocrine tumors of the uterine cervix: A therapeutic challenge for gynecologic oncologists

Neuroendocrine tumors (NETs) are aggressive diseases developing from neuroendocrine cells that most frequently involve the gastro-entero-pancreatic tract and the lung, but more rarely are found in almost all body tissues. Limited biological and clinical data are currently available for NETs in uncommon sites, such as female genital tract. NETs represent 0.9% to 1.5% of the tumors of the uterine cervix. They are more likely to have lymph-vascular space invasion and lymph node involvement, and to develop local and distant relapses when compared with the mostly common cervical squamous cell carcinomas or adenocarcinomas. Positive immunostaining for synaptophysin, chromogranin, CD56, and neuron-specific enolase is often detected in cervical NETs . The most recent editions of the World Health Organization Classification of Gynecologic Tract tumors grouped cervical carcinoid tumor and atypical carcinoid tumor into low-grade NETs and cervical small cell neuroendocrine carcinoma and large cell neuroendocrine carcinoma into high-grade NETs. High-risk HPV DNA is detected in almost all cervical high-grade NETs. No treatment guidelines, based on prospective, well-designed clinical trials, are currently available due to the rarity of these tumors. Many authors have reported different multimodality approaches, mainly derived from NETs of the lung. These usually consist in radical hysterectomy followed by adjuvant chemotherapy or concurrent chemoradiation for early stage disease, definitive concurrent chemoradiation sometimes preceded by neoadjuvant chemotherapy and followed by adjuvant chemotherapy for locally advanced disease, and palliative chemotherapy for metastatic disease. In this systematic review, we address the histologic classification of cervical NETs, analyze their pathogenesis and overall prognosis, and evaluate the different treatment modalities described in the literature, in order to offer a possible algorithm that may help the clinicians in diagnosing and treating patients with these uncommon and aggressive malignancies.

Small cell neuroendocrine carcinoma of the endometrium with pulmonary metastasis: A clinicopathologic study of a case and a brief review of the literature

Neuroendocrine carcinomas (NEC) of the female genital tract are aggressive and rare tumors that usually involve the cervix and ovary, and are seen rarely in the endometrium in perimenopausal or postmenopausal women. We presented a case of a73 year-old postmenopausal woman with vaginal bleeding and abdominal pain. A subsequent computerized tomography (CT) scan of pelvis showed an enlarged uterus (20,0 × 12,0 cm) with para-aortic and pelvic lymph node metastases. She underwent surgical debulking and staging of an endometrial tumor with omental metastasis and positive lymph nodes. The pathological diagnosis was primary small cell carcinoma (SCC) combined with endometrioid carcinoma of uterine corpus. Her final FIGO stage was IVB. Three months after surgery CT-total body showed a metastasis to left lung of SCC. Because the small-cell component of endometrial tumor showed a strong positivity for TTF1 as pulmonary counterpart a differential diagnosis with a primary small cell carcinoma of the lung should be made. Identifying an appropriate therapeutic management for SCC of endometrium is challenging since these are extremely rare tumors. An optimal initial therapeutic approach to this rare disease, especially at an advanced stage, has not yet been clearly defined. However, in these a multidisciplinary therapy, including surgery, chemotherapy, and radiotherapy represent until this time the only therapeutic option.

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Neuroendocrine carcinomas (NEC) of endometrium are aggressive and rare tumors.

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As pulmonary counterpart may express Thyroid transcription factor-1 (TTF-1).

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To date, no effective treatment protocol has been established for this rare type of tumor.

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A multidisciplinary therapy represents until this time the only therapeutic option.

Modeling the interactions between MC2R and ACTH models from human

Melanocortin system is composed of four peptide hormones namely α-, β-, -γ, and adrenocorticotropic hormone (ACTH), derived from post-translational cleavage of a polypeptide precursor 'proopiomelanocortin (POMC).' Among these hormones, ACTH, a 38 amino acid residue peptide fragment is an important hormone as it is involved in steroid secretion. In addition to this, to cite a few, this hormone is also known to induce variety of other effects, such as alterations in motor/sexual behavior, improvement in memory, and anti-inflammatory effects. To date, five melanocortin receptors (MC1R-MC5R) have been characterized with tissue-specific expression patterns and different binding affinities for each of the melanocortin hormones to regulate various biological functions. In the present work, three-dimensional (3D) models of MC2R and ACTH from human have been predicted, followed by docking and molecular dynamics simulation. While the 3D model of MC2R receptor has been predicted through threading approach, structure of ACTH was built based on ab initio technique. The MC2R model was later successfully docked onto the ACTH structure. Molecular dynamics (MD) simulation for 20 ns was used to compute the binding free energy of MC2R with ACTH model under implicit solvent conditions.

A retrospective clinicopathological analysis of small-cell carcinoma of the uterine cervix

Cervical cancer encompasses several histological types, including neuroendocrine tumors (NETs). Small-cell carcinoma of the uterine cervix (SCCC) is the most common and aggressive subtype of cervical NET. The objective of this case report was to investigate SCCC using a retrospective clinicopathological approach. Four cases of large (≥4 cm) SCCCs are presented in this case study. The patients were diagnosed with SCCC through a sequential hierarchy of physical examinations, laboratory reports, radiological reports, immunohistochemical and pathological tests. The diagnosis for each case was made at various stages (Ib1, Ib2, IIa2 and IIb, according to the FIGO staging system, 2000) and each of the patients received different multimodality therapeutic regimens. All the patients underwent radical hysterectomy and pelvic lymphadenectomy, followed by adjuvant chemotherapy. Neoadjuvant chemotherapy was administered prior to surgery in two of the patients. The clinical and pathological analyses were assessed using a retrospective measure, maintaining timely follow-ups. SCCC is a rare but serious gynecological malignancy. This condition has a poor prognosis due to its high aggressiveness, high rate of metastases and mortality. Furthermore, the rarity of this disease represents a hindrance to adequate research and development of novel, efficient therapeutic regimens.