Platinum-induced upregulation of ITGA6 promotes chemoresistance and spreading in ovarian cancer.

Platinum (PT)-resistant Epithelial Ovarian Cancer (EOC) grows as a metastatic disease, disseminating in the abdomen and pelvis. Very few options are available for PT-resistant EOC patients, and little is known about how the acquisition of PT-resistance mediates the increased spreading capabilities of EOC. Here, using isogenic PT-resistant cells, genetic and pharmacological approaches, and patient-derived models, we report that Integrin α6 (ITGA6) is overexpressed by PT-resistant cells and is necessary to sustain EOC metastatic ability and adhesion-dependent PT-resistance. Using in vitro approaches, we showed that PT induces a positive loop that, by stimulating ITGA6 transcription and secretion, contributes to the formation of a pre-metastatic niche enabling EOC cells to disseminate. At molecular level, ITGA6 engagement regulates the production and availability of insulin-like growth factors (IGFs), over-stimulating the IGF1R pathway and upregulating Snail expression. In vitro data were recapitulated using in vivo models in which the targeting of ITGA6 prevents PT-resistant EOC dissemination and improves PT-activity, supporting ITGA6 as a promising druggable target for EOC patients.

Long-Term Follow-Up Outcomes in Women with In Situ/Microinvasive Adenocarcinoma of the Uterine Cervix Undergoing Conservative Treatment-Cervical Adenocarcinoma Study Group Italian Society of Colposcopy and Cervico-Vaginal Pathology.

OBJECTIVE: The present study aimed to assess long-term follow-up outcomes in women with in situ/microinvasive adenocarcinoma (AC) of the uterine cervix treated conservatively. METHODS: Retrospective multi-institutional study including women with early glandular lesions and 5-year follow-up undergoing fertility-sparing treatment. Independent variables associated with recurrence were evaluated. Logistic regression analysis and Kaplan-Meier survival analysis with Logrank test were performed. RESULTS: Of 269 women diagnosed with in situ/microinvasive AC, 127 participants underwent conservative treatment. During follow-up, recurrences were found in nine women (7.1%). The only factor associated with recurrence during follow-up was positive high-risk Human Papillomavirus (hr-HPV) testing (odds ratio 6.21, confidence interval 1.47-26.08, p = 0.012). HPV positivity in follow-up showed a recurrence rate of 21.7% against 3.8% in patients who were HPV-negative (p = 0.002, Logrank test). Among women with negative high-risk HPV tests in follow-up, recurrences occurred in 20.0% of non-usual-type histology vs. 2.1% of usual-type cases (p = 0.005). CONCLUSION: HPV testing in follow-up is of pivotal importance in women with early glandular lesions undergoing conservative treatment, given its recurrence predictive value. However, women who are high-risk HPV-negative in follow-up with non-usual-type histopathology may represent a sub-population at increased risk of recurrences. Further studies should confirm these findings.

In Situ/Microinvasive Adenocarcinoma of the Uterine Cervix and HPV-Type Impact: Pathologic Features, Treatment Options, and Follow-Up Outcomes-Cervical Adenocarcinoma Study Group (CAS-Group).

It is unknown whether human papillomavirus (HPV) status impacts the prognosis of early stage cervical glandular lesions. This study assessed the recurrence and survival rates of in situ/microinvasive adenocarcinomas (AC) according to HPV status during a 5-year follow-up. The data were retrospectively analyzed in women with available HPV testing before treatment. One hundred and forty-eight consecutive women were analyzed. The number of HPV-negative cases was 24 (16.2%). The survival rate was 100% in all participants. The recurrence rate was 7.4% (11 cases, including four invasive lesions (2.7%)). Cox proportional hazards regression showed no difference in recurrence rate between HPV-positive and HPV-negative cases (p = 0.148). HPV genotyping, available for 76 women and including 9/11 recurrences, showed a higher relapse rate for HPV-18 than HPV-45 and HPV-16 (28.5%, 16.6%, and 9.52%, p = 0.046). In addition, 60% and 75% of in situ and invasive recurrences, respectively, were HPV-18 related. The present study showed that most ACs were positive for high-risk HPV, and the recurrence rate was unaffected by HPV status. More extensive studies could help evaluate whether HPV genotyping may be considered for recurrence risk stratification in HPV-positive cases.

Primary intestinal-type adenocarcinoma of the vulva. A case report and review of the literature.

Background: Primary non-squamous cell carcinomas of the vulva are rare entities including various tumor types. Among these, primary vulvar intestinal-type adenocarcinoma (vPITA) is extremely rare. Until 2021, less than twenty-five cases have been reported in the literature. Case presentation: We report a case of vPITA in a 63 years old woman with a histopathological diagnosis of signet-ring cell intestinal type adenocarcinoma at vulvar biopsy. Accurate clinical and pathological work-up excluded secondary metastatic localization, and vPITA was diagnosed. The patient was treated with radical vulvectomy and bilateral inguinofemoral dissection. Adjuvant chemo-radiotherapy was performed because of a positive lymph node. At 20 months follow-up the patient was alive and free of disease. Conclusion:  The prognosis of this very rare disease is unclear and optimal treatment is not well established. About 40% of clinical early-stage diseases reported in literature had positive inguinal nodes, more than in vulvar squamous cell carcinomas. A proper histopathologic and clinical diagnosis is mandatory to exclude secondary disease and to recommend an adequate treatment.

Extramammary Paget's Disease of the Vulva and Concomitant Premalignant/Malignant Vulvar Lesions: A Potential Challenge in Diagnosis and Treatment.

The aim of the present study was to evaluate the incidence of concomitant vulvar cancers or premalignant lesions in women surgically treated for extramammary Paget's disease of the vulva (EMPDV) through a multicenter case series. The medical records of all women diagnosed with and treated for EMPDV from January 2010 to December 2020 were retrospectively analyzed. Women with EMPDV and synchronous vulvar cancer, vulvar intraepithelial neoplasia (VIN) and/or lichen sclerosus (LS) at the histology report were included in the study. A total of 69 women eligible for the present study were considered. Concomitant vulvar lesions occurred in 22 cases (31.9%). A total of 11 cases of synchronous VIN (50%) and 14 cases (63.6%) of concomitant LS were observed. One patient (4.5%) had synchronous vulvar SCC (FIGO stage 1B). Women with EMPDV and concomitant premalignant/malignant vulvar lesions had a significantly higher rate of invasive EMPDV and wider lesions with an extravulvar involvement. The specific meaning of the association between EMPDV, VIN, SCC and LS remains unclear. The potential overlapping features between different vulvar lesions highlight the importance of dedicated gynecologists and pathologists in referral centers.

Parenchymal liver metastasis in advanced ovarian cancer: Can bowel involvement influence the frequency and the related mortality rate?

OBJECTIVE: This retrospective study estimates the frequency of parenchymal liver metastasis (PLM) and the overall survival (OS) rate of patients with FIGO Stage IIIC-IV Advanced Epithelial Ovarian Cancer (EOC) with bowel involvement. STUDY DESIGN: Between November 2008 and July 2020, all consecutive patients with FIGO Stage IIIC-IV EOC who underwent Visceral Peritoneal Debulking and bowel resection(s) at the Gynaecological Oncology Unit of "Centro di Riferimento Oncologico (CRO)", Aviano, Italy, without evidence of PLM at pre-operative imaging assessment, were included in the study. The presence and the time of the onset of PLM during the follow-up period were detected by diagnostic imaging (CT-scan, Ultrasound and PET). The OS of patients with and without PLM was compared. Considering the bowel's layers, the association between depth of bowel involvement, number of PLM, and the relative OS rate was evaluated. RESULTS: The median follow-up period was 47.3 (12-138) months. PLM occurred in 24/72 (33.0%) cases; the average onset time of PLM was 13 months. PLM was associated with increased significant mortality risk and an average OS of 33.2 versus 56.8 months (p < 0.001). The risk of developing PLM correlated directly with the depth of bowel involvement. However, there was no statistical difference between the layers in terms of OS at the end of the observational period. CONCLUSIONS: PLM occurred more frequently among patients with EOC and bowel involvement. The PLM arose within 15 months of follow-up and the frequency increased according to the depth of involvement. Particularly, the difference is remarkably higher starting from muscular layer where the total number of PLM arose significantly (p = 0.02). Although there was no significant difference among the infiltrated bowel layers in terms of OS, patients with bowel involvement up to muscular had a dramatic reduction in the OS rate during the first 30 months of follow-up.

Concurrent Endometrial Cancer in Women with Atypical Endometrial Hyperplasia: What Is the Predictive Value of Patient Characteristics?

BACKGROUND: The rate of concurrent endometrial cancer (EC) in atypical endometrial hyperplasia (AEH) can be as high as 40%. Some patient characteristics showed associations with this occurrence. However, their real predictive power with related validation has yet to be discovered. The present study aimed to assess the performance of various models based on patient characteristics in predicting EC in women with AEH. METHODS: This is a retrospective multi-institutional study including women with AEH undergoing definitive surgery. The women were divided according to the final histology (EC vs. no-EC). The available cases were divided into a training and validation set. Using k-fold cross-validation, we built many predictive models, including regressions and artificial neural networks (ANN). RESULTS: A total of 193/629 women (30.7%) showed EC at hysterectomy. A total of 26/193 (13.4%) women showed high-risk EC. Regression and ANN models showed a prediction performance with a mean area under the curve of 0.65 and 0.75 on the validation set, respectively. Among the best prediction models, the most recurrent patient characteristics were age, body mass index, Lynch syndrome, diabetes, and previous breast cancer. None of these independent variables showed associations with high-risk diseases in women with EC. CONCLUSIONS: Patient characteristics did not show satisfactory performance in predicting EC in AEH. Risk stratification in AEH based mainly on patient characteristics may be clinically unsuitable.

An Exceptional Response to Dostarlimab in Mismatch Repair Deficient, Microsatellite Instability-High and Platinum Refractory Endometrial Cancer.

Until recently, effective therapies for advanced endometrial cancer progressing to a platinum-based combination were lacking. In this setting, immunotherapy with anti PD-1/PDL-1 monoclonal antibodies is rising as a new paradigm in particular for patients with microsatellites instability/mismatch repair deficiency. In this case report, we describe an exceptional and rapid response to dostarlimab in a platinum refractory endometrial cancer patient with high disease burden harboring a mismatch repair deficiency.

Histopathological findings in hysterectomy for cervical stenosis in postmenopausal women: A retrospective case series.

OBJECTIVE: To analyze the histopathological findings in postmenopausal women who underwent hysterectomy for postsurgical cervical stenosis, evaluating the incidental findings of preinvasive or invasive uterine and cervical disease. METHODS: Retrospective case series of postmenopausal women who underwent hysterectomy for postsurgical cervical stenosis at Gynecological Oncology Unit of Istituto di Ricovero e Cura a Carattere Scientifico Centro di Riferimento Oncologico Aviano-National Cancer Institute from January 2014 to January 2021. RESULTS: During the study period, 36 women underwent hysterectomy for postsurgical cervical stenosis at our institution. Cervical stenosis occurred 10.2 ± 5.6 years from the onset of menopause. In particular, 26 (72.2%) patients underwent a single loop electrosurgical excision procedure or carbon dioxide (CO2)-laser conization before the onset of stenosis. The remaining 10 (27.8%) women had multiple surgical excision before the onset of stenosis. At the final histopathological analysis, 17 (47.2%) patients had a preinvasive or invasive gynecological disease. In particular, 9 cases of cervical disease (including 1 case of endocervical squamous cell carcinoma pT1a) and 6 cases of endometrial hyperplasia emerged. Also, 2 cases of tubo-ovarian diseases were found. CONCLUSIONS: Postsurgical cervical stenosis is a challenging clinical condition, especially in women treated for cervical intraepithelial neoplasia or microinvasive cervical cancer. As shown, cervical stenosis can prevent an adequate gynecological follow-up and a prompt diagnosis of malignancies. Therefore, postmenopausal women with cervical stenosis should be carefully counseled, and hysterectomy could be a reasonable option, especially in those cases in which a conservative approach is not feasible, failed, or is not accepted by the patient.

AKT Isoforms Interplay in High-Grade Serous Ovarian Cancer Prognosis and Characterization.

High-grade serous ovarian cancer (HGSOC) is among the deadliest gynecological malignancies. The acquired resistance to platinum-based therapies and the intrinsic heterogeneity of the disease contribute to the low survival rate. To improve patients' outcomes, new combinatorial approaches able to target different tumor vulnerabilities and enhance the efficacy of the current therapies are required. AKT inhibitors are promising antineoplastic agents able to act in synergy with PARP inhibitors, but the spectrum of patients who can benefit from this combination is unclear, since the role of the three different isoforms of AKT is still unknown. Here, we study the expression of AKT isoforms on a retrospective cohort of archive tissue by RT-droplet digital PCR (ddPCR) analyzing their association with the clinicopathological features of patients. Based on AKT1/AKT2 and AKT1/AKT3 ratios, we define four AKT classes which were related to patients' survival, tumor morphology and BRCA1 expression. Moreover, our results show that high AKT3 expression levels were frequently associated with tumors having classic features, a low number of mitoses and the presence of psammoma bodies. Overall, our study obtains new insights on AKT isoforms and their associations with the clinicopathological features of HGSOC patients. These evidences could help to better define the subsets of patients who can benefit from AKT and PARP inhibitors therapy in future clinical trials.

CIN2 in childbearing-age women: may colposcopy help choosing the proper management?

BACKGROUND: CIN2 is considered a biologically equivocal lesion falling between low- and high-grade cervical dysplasia, but it is often managed with cervical conization as a high-grade lesion. However, since cervical conization can lead to an increased risk of adverse obstetric events, it might be interesting to identify, by colposcopy, a subgroup of women with a low risk of "occult" CIN3 who could be managed with a "wait and see" approach. METHODS: All the women with CIN2 cervical biopsy from 1999 to 2019 were retrospectively identified. Their colposcopic patterns at the time of biopsy and the histopathological findings on the final cone specimen were compared. RESULTS: Among the 354 women with CIN2 biopsy included, the overall CIN3+ lesion rate on final cone specimen was 21.4%. The rate of CIN3 on final specimen was higher in women with G2 colposcopy compared to G1 (27.2% vs. 15.9%, P=0.01). Among women with G1 colposcopy, the rate of CIN3+ lesions was significantly higher in women with fine punctation (P=0.02) while no differences in women with thin acetowhite epithelium or fine mosaic emerged. CONCLUSIONS: In women with CIN2 biopsy, when a G2 pattern or G1 with fine punctation on colposcopy is detected, there is an increased risk of CIN3+ on final histology, therefore an excisional treatment should be preferred. Otherwise, in women with CIN2 biopsy and other G1 patterns on colposcopy, a "wait-and-see" approach could be considered.

Characteristics and patterns of care of endometrial cancer before and during COVID-19 pandemic.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) outbreak has correlated with the disruption of screening activities and diagnostic assessments. Endometrial cancer (EC) is one of the most common gynecological malignancies and it is often detected at an early stage, because it frequently produces symptoms. Here, we aim to investigate the impact of COVID-19 outbreak on patterns of presentation and treatment of EC patients. METHODS: This is a retrospective study involving 54 centers in Italy. We evaluated patterns of presentation and treatment of EC patients before (period 1: March 1, 2019 to February 29, 2020) and during (period 2: April 1, 2020 to March 31, 2021) the COVID-19 outbreak. RESULTS: Medical records of 5,164 EC patients have been retrieved: 2,718 and 2,446 women treated in period 1 and period 2, respectively. Surgery was the mainstay of treatment in both periods (p=0.356). Nodal assessment was omitted in 689 (27.3%) and 484 (21.2%) patients treated in period 1 and 2, respectively (p<0.001). While, the prevalence of patients undergoing sentinel node mapping (with or without backup lymphadenectomy) has increased during the COVID-19 pandemic (46.7% in period 1 vs. 52.8% in period 2; p<0.001). Overall, 1,280 (50.4%) and 1,021 (44.7%) patients had no adjuvant therapy in period 1 and 2, respectively (p<0.001). Adjuvant therapy use has increased during COVID-19 pandemic (p<0.001). CONCLUSION: Our data suggest that the COVID-19 pandemic had a significant impact on the characteristics and patterns of care of EC patients. These findings highlight the need to implement healthcare services during the pandemic.

Risks factors for anastomotic leakage in advanced ovarian cancer: A systematic review and meta-analysis.

OBJECTIVE: This systematic review and meta-analysis aimed to summarise the available evidence on the pre- and intra-operative risk factors for anastomotic leakage (AL) after bowel resection and anastomosis for ovarian cancer (OC). STUDY DESIGN: We searched online databases from Pubmed, Scopus, ScienceDirect, and Cochrane Library from inception to October 2020. Pre- and intra-operative risk factors for AL were considered as the primary outcomes. Research heterogeneity and bias were evaluated by I2 and by the Newcastle Ottawa scale, respectively. The study was registered with PROSPERO, CRD42018095225. RESULTS: The overall AL rate after OC surgery (median ± SD) was 5.3 ± 12% (277 AL on 5178 anastomoses). Thirteen non-randomised studies were included in the meta-analysis enrolling a total of 3274 patients. Pre albumin level ≤ 3 gr/dl, multiple bowel resections and primary cytoreductive surgery were associated with a significantly high risk of AL with a pooled OR of 5.29 (95% CI: 1.51-18.59), OR = 4.4 (95% CI: 1.19-16.66) and OR = 1.71 (95% CI: 1.05-2.77), respectively. Optimal cytoreduction, ASA score, ascites, and protective stoma were not associated with an increased risk of AL. CONCLUSION: Based on the best available evidence, preoperative albumin level <3 gr/dl, multiple bowel resections and primary cytoreductive surgery were associated with an increased risk for AL after bowel surgery for OC.

Histological patterns and intra-tumor heterogeneity as prognostication tools in high grade serous ovarian cancers.

OBJECTIVE: High grade serous ovarian carcinoma (HGSOC) is the most common type of malignant ovarian neoplasm and the main cause of ovarian cancer related deaths worldwide. Although novel biomarkers such as homologous recombination deficiency testing have been implemented into the clinical decision-making algorithm since diagnosis, morphological classification and immunohistochemistry analysis are essential for diagnostic purpose. This study aims at identifying histologic and clinical features that can be predictive of patients' prognosis. METHODS: Morphological and architectural characterization including SET (Solid-Endometroid-Transitional)/Classic features was carried out in a cohort of 234 patients analyzing 695 slides. From each slide tumor infiltrating lymphocyte (TILs), the presence of necrosis, the number of mitoses, the presence of psammoma bodies, giant cells and atypical mitoses were recorded. Morphological heterogeneity was quantified by the Shannon's diversity index (SDI) considering the percentage of each architectural pattern per patient's slide. RESULTS: The frequency of architectural patterns and morphological variables varied with respect of the surgical strategy (primary debulking surgery vs interval surgery after neoadjuvant chemotherapy). HGSOCs exhibiting SET features had a longer overall as well as progression free survival. Among SET features, pseudo-endometrioid and transitional like patterns had the best outcome, while it was heterogenous for solid pattern, that had better outcome for BRCA 1 negative and less heterogeneous tumors. In patients submitted to neoadjuvant chemotherapy a higher intratumor heterogeneity as defined by SDI was a negative independent prognostic factor. CONCLUSIONS: A comprehensive histological examination considering architectural patterns and their heterogeneity can help in prognostication of HGSOCs.

The Management of the Cotyledonoid Leiomyoma of the Uterus: A Narrative Review of the Literature.

Cotyledonoidleiomyoma is an unusual uterine myoma due to some ultrasound features that mimic a malignant lesion facilitating the choice of radical surgery. This study aims to summarize the ultrasound and the magnetic resonance imaging aspects of this atypical lesion, and also discuss surgical treatment and pathological exam. It included all English case reports or case series until August 2021 found through PubMed, Google Scholar, and Scopus. A total of 94 cotyledonoid leiomyomas were reported, with a median tumor size of 12 cm. The typical ultrasound image is characterized by a large solid heterogeneous mass, with high vascularity, no shadowing, and indistinct margins within the myometrium. Magnetic resonance imaging shows the presence of merging isointense nodules to the myometrium in T1-weighted images, hyperintense in T2-weighted images, and contrast agent enhancement. Surgical treatment consists of hysterectomy (75 cases, 80%) or myomectomy (19 cases, 20%), without evidence of recurrence if complete. The placenta-like appearance observed during surgery supports this rare fibroid hypothesis. The intraoperative frozen section can be considered. Microscopically, no atypical cells, signs of mitotic activity or cell necrosis are found. To conclude, some preoperative and intraoperative aspects of this lesion are distinctive and may lead surgeons to opt for conservative surgery.

Surveillance alone in stage I malignant ovarian germ cell tumors: a MITO (Multicenter Italian Trials in Ovarian cancer) prospective observational study.

OBJECTIVE: The aim of this study was to analyze the oncological outcome of stage I malignant ovarian germ cell tumors patients included in the MITO-9 study to identify those who might be recommended routine surveillance alone after complete surgical staging. METHODS: MITO-9 was a prospective observational study analyzing data collected between January 2013 and December 2019. Three groups were identified: group A included 13 patients stage IA dysgerminoma and IAG1 immature teratoma; group B included 29 patients with stage IB-C dysgerminomas, IA-C G2-G3 immature teratomas and stage IA mixed malignant ovarian germ cell tumors and yolk sac tumors; and group C included five patients (two patients with stage IC1 and one patient with stage IC2 yolk sac tumors and two patients with mixed-stage IC2 malignant ovarian germ cell tumors). RESULTS: A total of 47 patients with stage I conservatively treated malignant ovarian germ cell tumors were analyzed. Two patients in group B were excluded from the routine surveillance alone group due to positive surgical restaging. Therefore, a total of 45 patients were included in the study. Median follow-up was 46.2 months (range; 6-83). In total, 14 of 45 patients (31.1%) received chemotherapy, while 31 (68.9%%) underwent surveillance alone. One patient in group A, with stage IA dysgerminoma had a relapse, successfully managed with conservative surgery and chemotherapy. None of the patients in group B and C relapsed. All patients were alive at completion of the study. Overall, among 31 patients (68.9%) who underwent surveillance alone, only one patient relapsed but was treated successfully. CONCLUSIONS: Our data showed that close surveillance alone could be an alternative option to avoid adjuvant chemotherapy in properly staged IB-C dysgerminomas, IA-IC G2-G3 immature teratomas, and IA mixed malignant ovarian germ cell tumors with yolk sac tumor component.

Cotyledonoid Leiomyoma Clinical Characteristics, Imaging Features, and Review of the Literature.

Cotyledonoid leiomyoma of the uterus is a rare variant of benign uterine leiomyoma. It has a favorable attitude, despite some ultrasound presentations. A bulky uterus with a heterogeneous mass with irregular margins, high vascularity, and infiltration of the myometrium can induce the suspicion of a malignant mesenchymal tumor and lead to a radical surgical treatment. If present, some imaging features may suggest this rare type of leiomyoma, thus avoiding extensive surgery, especially in young nulliparous women. We report 13 cases of cotyledonoid leiomyoma with clinical characteristics, imaging features, and a literature review.

Intestinal occlusion by gynecological cancers treated by percutaneous endoscopic gastrostomy and lanreotide: an Aviano National Cancer Institute experience.

The Commentary reports on our experience in Centro di Riferimento Oncologico IRCCS Aviano about the integrated and combined treatment with percutaneous endoscopic gastrostomy and lanreotide in patients with bowel obstructions by ovarian cancer and peritoneal carcinomatosis. We treated patients with gynecological cancers and bowel obstruction with percutaneous endoscopic gastrostomy and, when patients were partially responsive, with lanreotide. We registered a constant overall benefit for the quality of life and for the control of symptoms, which is very important especially during the home care follow-up of terminal patients.

CDKN1B mutation and copy number variation are associated with tumor aggressiveness in luminal breast cancer.

The CDKN1B gene, encoding for the CDK inhibitor p27kip1 , is mutated in defined human cancer subtypes, including breast, prostate carcinomas and small intestine neuroendocrine tumors. Lessons learned from small intestine neuroendocrine tumors suggest that CDKN1B mutations could be subclonal, raising the question of whether a deeper sequencing approach could lead to the identification of higher numbers of patients with mutations. Here, we addressed this question and analyzed human cancer biopsies from breast (n = 396), ovarian (n = 110) and head and neck squamous carcinoma (n = 202) patients, using an ultra-deep sequencing approach. Notwithstanding this effort, the mutation rate of CDKN1B remained substantially aligned with values from the literature, showing that essentially only hormone receptor-positive breast cancer displayed CDKN1B mutations in a relevant number of cases (3%). However, the analysis of copy number variation showed that another fraction of luminal breast cancer displayed loss (8%) or gain (6%) of the CDKN1B gene, further reinforcing the idea that the function of p27kip1 is important in this type of tumor. Intriguingly, an enrichment for CDKN1B alterations was found in samples from premenopausal luminal breast cancer patients (n = 227, 4%) and in circulating cell-free DNA from metastatic luminal breast cancer patients (n = 59, 8.5%), suggesting that CDKN1B alterations could correlate with tumor aggressiveness and/or occur later during disease progression. Notably, many of the identified somatic mutations resulted in p27kip1 protein truncation, leading to loss of most of the protein or of its C-terminal domain. Using a gene-editing approach in a luminal breast cancer cell line, MCF-7, we observed that the expression of p27kip1 truncating mutants that lose the C-terminal domains failed to rescue most of the phenotypes induced by CDKN1B gene knockout, indicating that the functions retained by the C-terminal portion are critical for its role as an oncosuppressor, at least in luminal breast cancer. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.