Cost-Effectiveness of Unselected Multigene Germline and Somatic Genetic Testing for Epithelial Ovarian Cancer.

BACKGROUND: Parallel panel germline and somatic genetic testing of all patients with ovarian cancer (OC) can identify more pathogenic variants (PVs) that would benefit from PARP inhibitor (PARPi) therapy, and allow for precision prevention in unaffected relatives with PVs. In this study, we estimate the cost-effectiveness and population impact of parallel panel germline and somatic BRCA testing of all patients with OC incorporating PARPi therapy in the United Kingdom and the United States compared with clinical criteria/family history (FH)-based germline BRCA testing. We also evaluate the cost-effectiveness of multigene panel germline testing alone. METHODS: Microsimulation cost-effectiveness modeling using data from 2,391 (UK: n=1,483; US: n=908) unselected, population-based patients with OC was used to compare lifetime costs and effects of panel germline and somatic BRCA testing of all OC cases (with PARPi therapy) (strategy A) versus clinical criteria/FH-based germline BRCA testing (strategy B). Unaffected relatives with germline BRCA1/BRCA2/RAD51C/RAD51D/BRIP1 PVs identified through cascade testing underwent appropriate OC and breast cancer (BC) risk-reduction interventions. We also compared the cost-effectiveness of multigene panel germline testing alone (without PARPi therapy) versus strategy B. Unaffected relatives with PVs could undergo risk-reducing interventions. Lifetime horizon with payer/societal perspectives, along with probabilistic/one-way sensitivity analyses, are presented. Incremental cost-effectiveness ratio (ICER) and incremental cost per quality-adjusted life year (QALY) gained were compared with £30,000/QALY (UK) and $100,000/QALY (US) thresholds. OC incidence, BC incidence, and prevented deaths were estimated. RESULTS: Compared with clinical criteria/FH-based BRCA testing, BRCA1/BRCA2/RAD51C/RAD51D/BRIP1 germline testing and BRCA1/BRCA2 somatic testing of all patients with OC incorporating PARPi therapy had a UK ICER of £51,175/QALY (payer perspective) and £50,202/QALY (societal perspective) and a US ICER of $175,232/QALY (payer perspective) and $174,667/QALY (societal perspective), above UK/NICE and US cost-effectiveness thresholds in the base case. However, strategy A becomes cost-effective if PARPi costs decrease by 45% to 46% or if overall survival with PARPi reaches a hazard ratio of 0.28. Unselected panel germline testing alone (without PARPi therapy) is cost-effective, with payer-perspective ICERs of £11,291/QALY or $68,808/QALY and societal-perspective ICERs of £6,923/QALY or $65,786/QALY. One year's testing could prevent 209 UK BC/OC cases and 192 deaths, and 560 US BC/OC cases and 460 deaths. CONCLUSIONS: Unselected panel germline and somatic BRCA testing can become cost-effective, with a 45% to 46% reduction in PARPi costs. Regarding germline testing, unselected panel germline testing is highly cost-effective and should replace BRCA testing alone.

Patient decision aids in mainstreaming genetic testing for women with ovarian cancer: A prospective cohort study.

OBJECTIVE: To evaluate patient preference for short (gist) or detailed/extensive decision aids (DA) for genetic testing at ovarian cancer (OC) diagnosis. DESIGN: Cohort study set within recruitment to the Systematic Genetic Testing for Personalised Ovarian Cancer Therapy (SIGNPOST) study (ISRCTN: 16988857). SETTING: North-East London Cancer Network (NELCN) population. POPULATION/SAMPLE: Women with high-grade non-mucinous epithelial OC. METHODS: A more detailed DA was developed using patient and stakeholder input following the principles/methodology of IPDAS (International Patients Decision Aids Standards). Unselected patients attending oncology clinics evaluated both a pre-existing short and a new long DA version and then underwent mainstreaming genetic testing by a cancer clinician. Appropriate inferential descriptive and regression analyses were undertaken. MAIN OUTCOME MEASURES: Satisfaction, readability, understanding, emotional well-being and preference for long/short DA. RESULTS: The mean age of patients was 66 years (interquartile range 11), and 85% were White British ethnicity. Of the participants, 74% found DAs helpful/useful in decision-making. Women reported higher levels of satisfaction (86% versus 58%, p < 0.001), right amount of information provided (76.79% versus49.12%, p < 0.001) and improved understanding (p < 0.001) with the long DA compared with the short DA. There was no statistically significant difference in emotional outcomes (feeling worried/concerned/reassured/upset) between 'short' and 'long' DA; 74% of patients preferred the long DA and 24% the short DA. Patients undergoing treatment (correlation coefficient (coef) = 0.603; 95% CI 0.165-1.041, p = 0.007), those with recurrence (coef = 0.493; 95% CI 0.065-0.92, p = 0.024) and older women (coef = 0.042; 95% CI 0.017-0.066, p = 0.001) preferred the short DA. Ethnicity did not affect outcomes or overall preference for long/short DA. CONCLUSIONS: A longer DA in OC patients has higher satisfaction without increasing emotional distress. Older women and those undergoing treatment/recurrence prefer less extensive information, whereas those in remission preferred a longer DA.

Practical Guidance for Measuring and Reporting Surgical Margins in Vulvar Cancer.

Surgical resection with free surgical margins is the cornerstone of successful primary treatment of vulvar squamous cell carcinoma (VSCC). In general reexcision is recommended when the minimum peripheral surgical margin (MPSM) is <8 mm microscopically. Pathologists are, therefore, required to report the minimum distance from the tumor to the surgical margin. Currently, there are no guidelines on how to make this measurement, as this is often considered straightforward. However, during the 2018 Annual Meeting of the British Association of Gynaecological Pathologists (BAGP), a discussion on this topic revealed a variety of opinions with regard to reporting and method of measuring margin clearance in VSCC specimens. Given the need for uniformity and the lack of guidance in the literature, we initiated an online survey in order to deliver a consensus-based definition of peripheral surgical margins in VSCC resections. The survey included questions and representative diagrams of peripheral margin measurements. In total, 57 pathologists participated in this survey. On the basis of consensus results, we propose to define MPSM in VSCC as the minimum distance from the peripheral edge of the invasive tumor nests toward the inked peripheral surgical margin reported in millimeters. This MPSM measurement should run through tissue and preferably be measured in a straight line. Along with MPSM, other relevant measurements such as depth of invasion or tumor thickness and distance to deep margins should be reported. This manuscript provides guidance to the practicing pathologist in measuring MPSM in VSCC resection specimens, in order to promote uniformity in measuring and reporting.

Lynch syndrome screening in gynaecological cancers: results of an international survey with recommendations for uniform reporting terminology for mismatch repair immunohistochemistry results.

AIMS: Lynch syndrome (LS) is associated with an increased risk of developing endometrial carcinoma (EC) and ovarian carcinoma (OC). There is considerable variability in current practices and opinions related to screening of newly diagnosed patients with EC/OC for LS. An online survey was undertaken to explore the extent of these differences. METHODS AND RESULTS: An online questionnaire was developed by a panel of experts and sent to all members of the British Association of Gynaecological Pathologists (BAGP) and the International Society of Gynecological Pathologists (ISGyP). Anonymised results were received and analysed. Thirty-six BAGP and 44 ISGyP members completed the survey. More than 90% of respondents were aware of the association of LS with both EC and OC, but 34% were not aware of specific guidelines for LS screening. Seventy-one per cent of respondents agreed that universal screening for LS should be carried out in all newly diagnosed EC cases, with immunohistochemistry (IHC) alone as the preferred approach. Only 36% of respondents currently performed IHC or microsatellite instability testing on all newly diagnosed EC cases, with most of the remaining respondents practising selective screening, based on clinical or pathological features or both. A significant minority of respondents (35%) believed that patient consent was required before performance of mismatch repair (MMR) protein IHC. Almost all respondents favoured the use of standardised terminology for reporting MMR protein staining results, and this is proposed herein. CONCLUSION: There is wide support for universal LS screening in patients with EC, but this survey highlights areas of considerable variation in practice.

Histopathologic response to neoadjuvant chemotherapy as a prognostic biomarker in tubo-ovarian high-grade serous carcinoma: updated Chemotherapy Response Score (CRS) results.

OBJECTIVE: The Chemotherapy Response Scoring (CRS) system was developed to enable reproducible reporting of histologic tumor response in interval debulking specimens following neoadjuvant chemotherapy in advanced stage tubo-ovarian high-grade serous carcinoma. This prognostic biomarker has been included in ovarian cancer pathology reporting guidelines (International Collaboration on Cancer Reporting, College of American Pathologists) and in the upcoming European Society for Medical Oncology-European Society of Gynaecological Oncology (ESMO-ESGO) guidelines for ovarian cancer management. We present follow-up data on the CRS validation initiatives and suggest research with novel therapeutic agents incorporating this biomarker. METHODS: The cohort on whom CRS was originally developed was analyzed after an extended follow-up of an additional 36 months. The CRS histopathologic scoring system was applied to omental sections obtained at interval surgery from all 80 patients. Progression-free and overall survival were re-calculated. RESULTS: After a median follow-up of 4.3 years the CRS score predicted progression-free survival with an HR of 0.39 (95% CI 0.21 to 0.70), p = 0.002 adjusted for age, stage, and debulking status (median 1.08 vs 2.27 years for CRS1/2 vs CRS3). CRS was also predictive of overall survival with an HR of 0.17 (95% CI 0.07 to 0.44), p = 0.0002 adjusted for age, stage, and debulking status (median 2.55 vs 5.47 years for CRS1/2 vs CRS3). CONCLUSION: CRS3 is a reproducible prognostic biomarker for improved progression-free and overall survival in stage 3C or 4 tubo-ovarian high-grade serous carcinoma after neoadjuvant chemotherapy. The score, obtained at interval debulking surgery, can help facilitate research and biomarker driven first-line treatment of patients with advanced ovarian cancer.

Extrauterine high-grade serous carcinomas with bilateral adnexal involvement as the only two disease sites are clonal based on tp53 sequencing results: implications for biology, classification, and staging.

A previous multicenter study of 67 cases of Stage I/II tubo-ovarian high-grade serous carcinoma with complete tubal sampling identified 7 cases in which there were only two disease sites, comprising tumor involving opposite adnexa with no extra-adnexal involvement. This study aimed to determine whether such low-stage extrauterine high-grade serous carcinomas with only two sites of involvement, located on opposite adnexa, have identical or different TP53 mutations in order to investigate their clonal relationship. DNA extracted from both sites of involvement was subjected to TP53 sequencing (n=6) or sequencing of one site and mutation confirmation by droplet digital PCR for the other site (n=1). Of the 7 cases analyzed, 1 case had unilateral serous tubal intraepithelial carcinoma with contralateral ovarian high-grade serous carcinoma, 3 had tubal high-grade serous carcinomas (±serous tubal intraepithelial carcinoma) with contralateral ovarian high-grade serous carcinoma, 2 had bilateral ovarian high-grade serous carcinomas with normal tubes, and 1 had bilateral fallopian tube high-grade serous carcinoma with normal ovaries. All 7 cases showed identical TP53 mutations in tumor from both disease sites. Therefore, these rare cases of high-grade serous carcinoma confined to opposite adnexa all show clonal identity between the two sites of involvement, suggesting unifocal origin and metastasis rather than multifocal origin. Our results suggest that serous tubal intraepithelial carcinoma or adnexal high-grade serous carcinoma can metastasize to the contralateral adnexa without peritoneal involvement. Given the clonal relationship between the two sites, such cases should be considered stage II, with stage I reserved for cases with unilateral and unifocal adnexal involvement. Furthermore, serous tubal intraepithelial carcinoma without invasion should be taken to constitute a disease site for staging purposes.

Disease Distribution in Low-stage Tubo-ovarian High-grade Serous Carcinoma (HGSC): Implications for Assigning Primary Site and FIGO Stage.

The latest FIGO and TNM (eighth edition) staging systems for ovarian, tubal, and peritoneal neoplasms require primary site assignment as tubal/ovarian/peritoneal, but provide no guidance or criteria. Fewer than 10% of extrauterine high-grade serous carcinoma (HGSC) cases present at low stage (stage I/II). Low-stage cases offer a unique opportunity to understand the pattern of disease early in its evolution prior to wide dissemination and provide valuable evidence for guiding specimen handling and tumor staging. This study aimed to examine disease distribution in low-stage tubo-ovarian HGSC. Anonymized pathology reports of 152 stage I/II extrauterine HGSCs from 6 teaching hospitals were analyzed: group 1 (n=67) comprised cases with complete tubal examination by Sectioning and Extensively Examining the FIMbriated end of the tube (SEE-FIM) and group 2 (n=85) consisted of cases without documentation of both tubes being fully examined by the SEE-FIM or a SEE-FIM-like protocol. The stage, site/pattern of involvement, site/size of largest tumor focus and laterality of tubal and ovarian involvement were recorded. Tubal mucosal involvement was present in 95% of optimally examined cases and many factors influenced detection of tubal disease. Bilateral involvement, suggestive of metastasis, was significantly more frequent in the ovaries (35%) than the tubes (9%) (P<0.0001, Fisher exact test). No case showed a complete absence of tubal/ovarian involvement, questioning the biological existence of primary peritoneal HGSC. Disease distribution in low-stage cases supports a tubal origin for most HGSCs. Detailed tubal sampling upstages some apparent stage I cases through detection of microscopic tubal involvement.

A comparison of p53 and WT1 immunohistochemical expression patterns in tubo-ovarian high-grade serous carcinoma before and after neoadjuvant chemotherapy.

AIMS: The treatment of patients with tubo-ovarian high-grade serous carcinoma (HGSC) is increasingly based on diagnosis on small biopsy samples, and the first surgical sample is often taken post-chemotherapy. p53 and WT1 are important diagnostic markers for HGSC. The effect of neoadjuvant chemotherapy on p53 and WT1 expression has not been widely studied. We aimed to compare p53 and WT1 expression in paired pre-chemotherapy and post-chemotherapy samples of HGSC. METHODS AND RESULTS: Immunohistochemistry (IHC) was carried out for p53 and WT1 on paired omental HGSC samples pre-chemotherapy and post-chemotherapy. p53 IHC was recorded as normal (wild-type) or abnormal (mutation-type), and was further classified as overexpression, complete absence, or cytoplasmic. WT1 IHC was classified as positive or negative. A subset of cases were further assessed for the extent of nuclear immunoreactivity of WT1 by use of the H-score. Fifty-seven paired samples were stained with p53. Fifty-six of 57 (98%) cases showed mutation-type p53 staining. Pre-chemotherapy and post-chemotherapy IHC results were concordant in 55 of 57 (96%) cases. For WT1, pre-chemotherapy and post-chemotherapy IHC results were concordant in 56 of 58 (97%) cases. In 23 paired WT1 cases, the mean post-treatment H-score decreased from 227 [range 20-298, standard deviation (SD) 64] to 151 (range 0-288, SD 78) (P = 0.0008). CONCLUSIONS: Immunohistochemical expression of p53 (abnormal/mutation-type pattern) and WT1 in HGSC is almost universal and is largely concordant before and after chemotherapy. This finding underscores the reliability of these diagnostic markers in small samples and in surgical samples following neoadjuvant chemotherapy, with very few exceptions. A novel finding was the significant diminution in intensity of WT1 staining following chemotherapy.

Persistence of fimbrial tissue on the ovarian surface after salpingectomy.

BACKGROUND: Salpingectomy is recommended as a risk-reducing strategy for epithelial tubo-ovarian cancer. The gold standard procedure is complete tubal excision. OBJECTIVE: The purpose of this study was to assess the presence of residual fimbrial/tubal tissue on ovarian surfaces after salpingectomy. STUDY DESIGN: Prospective analysis of patients who underwent salpingo-oophorectomy with or without hysterectomy for benign indications, early cervical cancer, or low-risk endometrial cancer at a UK National Health Service Trust. Salpingectomy with or without hysterectomy was performed initially, followed by oophorectomy within the same operation. Separately retrieved tubes and ovaries were sectioned serially and examined completely histologically. The main outcome measure was histologically identified fimbrial/ tubal tissue on ovarian surface. Chi-square/Fisher's exact tests were used to evaluate categoric variables. RESULTS: Twenty-five consecutive cases (mean age, 54.8 ± 5.0 years) that comprised 41 adnexae (unilateral, 9; bilateral, 16) were analyzed. Seventeen (68.0%), 5 (20.0%), and 3 (12.0%) procedures were performed by consultant gynecologists, subspecialty/specialist trainees, and consultant gynecologic oncologists, respectively. Twelve of 25 procedures (48.0%) were laparoscopic, and 13 of 25 procedures (52.0%) involved laparotomy. Four of 25 patients (16.0%; 95% confidence interval, 4.5-36.1%) or 4 of 41 adnexae (9.8%; 95% confidence interval, 2.7-23.1%) showed residual microscopic fimbrial tissue on the ovarian surface. Tubes/ovaries were free of adhesions in 23 cases. Two cases had dense adnexal adhesions, but neither had residual fimbrial tissue on the ovary. Residual fimbrial tissue was not associated significantly with surgical route or experience (consultant, 3/20 [15%]; trainee, 1/5 [20%]; P=1.0). CONCLUSION: Residual fimbrial tissue remains on the ovary after salpingectomy in a significant proportion of cases and could impact the level of risk-reduction that is obtained.

A Case of Stage 4B Seromucinous Ovarian Borderline Tumor With Endometriosis and Review of the Literature.

Ovarian mucinous borderline tumors are traditionally divided into 2 morphologic groups: endocervical type, also known as seromucinous, and intestinal type. We present a case of stage 4B seromucinous ovarian borderline tumor with endometriosis and review the literature. At the time of writing, this is believed to be the first case of a seromucinous borderline tumor reported at such an advanced stage.

The Chemotherapy Response Score (CRS): Interobserver Reproducibility in a Simple and Prognostically Relevant System for Reporting the Histologic Response to Neoadjuvant Chemotherapy in Tuboovarian High-grade Serous Carcinoma.

A 3-tier histopathologic scoring system, the chemotherapy response score (CRS), was previously devised for reporting the histologic response to neoadjuvant chemotherapy in interval debulking surgery specimens of stage IIIc/IV tuboovarian high-grade serous carcinoma. This has been shown to predict the outcome and offer additional information to other methods of assessing the treatment response. In the present study, the reproducibility of this scoring system was assessed by determining the interobserver agreement among reporting pathologists. A total of 5 groups each comprising 3 pathologists with different levels of expertise were selected. The participants underwent an online tutorial on how to apply the CRS system. 40 cases (38 cases in 2 appraiser groups) were scored individually by each of the 15 pathologists. The interobserver reproducibility was calculated using Fleiss' κ, Kendall's coefficient of concordance, and the absolute agreement between (a) individual pathologists within 1 group, (b) with the majority score agreement between all groups, and (c) with all individual scores. The CRS system was found to be highly reproducible among all the pathologists' groups (κ=0.761). The agreement in identifying the group of patients with the best response to chemotherapy was exceptionally high (κ=0.926). We conclude that CRS has a high interobserver reproducibility, especially in identifying the subgroup of patients with the best chemotherapy response, justifying its inclusion in clinical trials and reporting practice.

Pulmonary benign metastasizing uterine leiomyoma (PBML): a case report and review of the literature.

Benign metastasizing leiomyoma (BML) is a rare disorder characterized by the presence of benign smooth muscle tumours in extrauterine sites, typically the lungs. It classically involves perimenopausal women with a history of uterine surgery. The condition follows an indolent course but may cause clinical symptoms with large or widespread lesions. Case presentation: The authors report the case of a 47-year-old female who presented with a 6-month history of irregular vaginal bleeding and severe hot flushes. The patient had no previous history of gynaecological surgery. Ultrasonography and subsequent MRI identified a suspicious 105×65 mm mass involving the right uterine cornu and broad ligament. Computed tomography identified bilateral lung nodules, suspicious for metastases. Histological assessment of the final uterine surgical specimen identified a benign dissecting leiomyoma involving the broad ligament and cervix. BML was diagnosed after thoracoscopic resection of a lung lesion which revealed a histologically identical tumour with entrapped normal lung alveoli. Clinical discussion: This case shows that there is a minority of patients without previous uterine surgery who still go on to develop pulmonary BML. In our case, a combined treatment approach was adopted, involving substitution of hormone replacement therapy to a non-hormonal alternative, thoracoscopic resection of lung lesions and interval surveillance imaging of the chest. Conclusions: BML is a rare condition but should be considered as a differential in women with pulmonary nodules and a history of uterine leiomyomata. Its diagnosis and subsequent counselling can be challenging; therefore cases should be treated by multidisciplinary teams in tertiary specialized centres.

Is differentiated vulval intraepithelial neoplasia the precursor lesion of human papillomavirus-negative vulval squamous cell carcinoma?

Vulval squamous cell carcinoma appears to arise via 2 distinct pathways. A significant minority are associated with oncogenic human papillomavirus (HPV) infection and undifferentiated vulval intraepithelial neoplasia (VIN). However, the majority arises in the absence of HPV, on a background of chronic inflammation. Until recently, it was assumed that lichen sclerosus was the underlying inflammatory condition in the majority of HPV-negative cancers. This pathway of carcinogenesis has been less well studied than the HPV pathway. Emerging evidence implicates differentiated VIN (DVIN), rather than lichen sclerosus, as the most likely precursor lesion in HPV-negative vulval squamous cell carcinoma. Here we discuss the clinical and molecular evidence that implicates DVIN as a lesion with a high malignant potential. This lesion is probably underdiagnosed and may be undertreated. Better recognition of DVIN by gynecologists and pathologists may therefore offer an opportunity to prevent some vulval cancers.

Implementation of Multigene Germline and Parallel Somatic Genetic Testing in Epithelial Ovarian Cancer: SIGNPOST Study.

We present findings of a cancer multidisciplinary-team (MDT) coordinated mainstreaming pathway of unselected 5-panel germline BRCA1/BRCA2/RAD51C/RAD51D/BRIP1 and parallel somatic BRCA1/BRCA2 testing in all women with epithelial-OC and highlight the discordance between germline and somatic testing strategies across two cancer centres. Patients were counselled and consented by a cancer MDT member. The uptake of parallel multi-gene germline and somatic testing was 97.7%. Counselling by clinical-nurse-specialist more frequently needed >1 consultation (53.6% (30/56)) compared to a medical (15.0% (21/137)) or surgical oncologist (15.3% (17/110)) (p < 0.001). The median age was 54 (IQR = 51-62) years in germline pathogenic-variant (PV) versus 61 (IQR = 51-71) in BRCA wild-type (p = 0.001). There was no significant difference in distribution of PVs by ethnicity, stage, surgery timing or resection status. A total of 15.5% germline and 7.8% somatic BRCA1/BRCA2 PVs were identified. A total of 2.3% patients had RAD51C/RAD51D/BRIP1 PVs. A total of 11% germline PVs were large-genomic-rearrangements and missed by somatic testing. A total of 20% germline PVs are missed by somatic first BRCA-testing approach and 55.6% germline PVs missed by family history ascertainment. The somatic testing failure rate is higher (23%) for patients undergoing diagnostic biopsies. Our findings favour a prospective parallel somatic and germline panel testing approach as a clinically efficient strategy to maximise variant identification. UK Genomics test-directory criteria should be expanded to include a panel of OC genes.

British Gynaecological Cancer Society (BGCS) vulval cancer guidelines: Recommendations for practice.

The purpose of this guideline is to collate evidence and propose evidence-based guidelines for the diagnosis and management of adult patients with vulva carcinoma treated in the UK. Malignant melanoma may present via similar routes and will be discussed. The reader is referred to the Ano-uro-genital Mucosal Melanoma Full Guideline [1] for more detailed recommendations. The management of vulval sarcoma is outside of the scope of this guideline. For further information, including details of guideline development and GRADE of recommendations, please see BGCS website for details (https://www.bgcs.org.uk/professionals/guidelines-for-recent-publications/).

Uterine Serous Carcinomas Frequently Metastasize to the Fallopian Tube and Can Mimic Serous Tubal Intraepithelial Carcinoma.

We investigated the frequency, histopathologic, and immunohistochemical characteristics of tubal involvement in uterine serous carcinoma (USC) and aimed to clarify the relationship between "serous tubal intraepithelial carcinoma (STIC)" and USC in these cases. Cases of USC with complete tubal examination were prospectively collected and reviewed for the presence of tubal involvement. Immunohistochemical analysis for p53 and WT1 was performed on the endometrial and tubal tumor in cases with tubal involvement. Of 161 USC cases (pure USC or a component of a mixed carcinoma or a carcinosarcoma), 32 (20%) showed tubal involvement (unilateral: n=19; bilateral: n=13). The uterine tumors in cases with tubal involvement showed a trend toward increased likelihood of deep myometrial and lymphovascular invasion (LVI) compared with those without tubal involvement. The tubal fimbriae were involved in 15/32 cases. Tubal involvement was mucosal in 30/32 cases, mural in 14/32, serosal in 5/32, invasive in 22/32, and there was LVI in the tube in 13/32. STIC-like features were seen in 17/32 cases (7 as the only pattern of involvement, 9 with associated invasive carcinoma, and 5 with LVI). Immunostaining showed complete concordance of p53 and WT1 between the endometrial and tubal tumors in 26/32 cases, the majority being WT1 negative or only focally positive (19/26), and all exhibiting mutation-type p53 staining. On the basis of the histologic and immunohistochemical features, the tubal tumor was considered to represent metastatic USC in 26/32 cases, most likely metastatic USC in 2/32 cases, an independent tubal primary tumor in 3/32 cases, and to be of uncertain origin in the 1 remaining case. STIC-like lesions were considered to represent metastatic USC in 12/17 cases, most likely metastatic USC in 2/17 cases, an independent tubal primary in 2/17 cases, and of uncertain origin in the 1 remaining case. Tubal involvement, including STIC-like lesions, is seen in one fifth of USC when the tubes are examined in their entirety. The tubal involvement is metastatic in the vast majority of cases. Immunohistochemical studies assist, in most cases, in confirming the metastatic nature of the tubal disease. Consideration should be given to completely examining the fallopian tubes in apparent stage I or II USCs, as this will result in upstaging in a significant minority of cases.