Citations

PURPOSE Patients with breast cancer requiring postmastectomy radiation therapy (PMRT) often desire breast reconstruction. Reconstructions can be adversely affected by PMRT, and fear of reconstruction complications has discouraged adoption of short-course radiation therapy used after lumpectomy. To fill the evidence gap, we conducted a noninferiority trial of hypofractionated versus conventional PMRT in patients undergoing breast reconstruction. The primary outcome was reconstruction complication rate, a composite of wound healing, readmission, capsular contracture, unplanned reoperation, and reconstruction failure. METHODS Women with unilateral invasive breast cancer with planned immediate or delayed reconstruction and PMRT were randomly assigned (1:1) to 50 Gy (25 fractions/5 weeks) or 42.56 Gy (16 fractions/3 weeks). This study was designed with a noninferiority margin of 10%, assuming a 2-year reconstruction complication rate of 25% with conventional PMRT. Randomization was stratified by immediate versus delayed and autologous versus implant-only reconstruction. RESULTS Between 2018 and 2021, 898 patients enrolled with a median follow-up of 3.9 years; 825 patients were evaluable for the primary end point. The 24-month reconstruction complication rates were 12.3% (52/422) with hypofractionated PMRT and 10.2% (41/403) with conventional PMRT, corresponding to an estimated difference of -2.1% (95% CI, -6.5 to 2.2). The complication rate was higher (regardless of arm) with implant-only versus autologous reconstruction (odds ratio = 1.65). There was no statistically significant difference in 36-month locoregional recurrence rates: 1.5% (95% CI, 0.7 to 3.2) with hypofractionated and 2.2% (95% CI, 1.1 to 4.3) with conventional PMRT. Acute and late toxicity rates were not statistically different. CONCLUSION A 16-fraction course of hypofractionated PMRT is safe and noninferior to conventional PMRT in women undergoing breast reconstruction after mastectomy.

Abstract Background Opportunistic bilateral salpingectomy (OBS), the removal of fallopian tubes during hysterectomy or instead of tubal ligation, is recommended to reduce ovarian cancer risk. However, data on the effectiveness of prophylactic OBS is limited. Methods This population-based retrospective cohort included individuals aged 18–80 in Ontario, Canada, who underwent OBS or comparator surgeries (hysterectomy with ovarian and tubal conservation or tubal ligation) from 2011 to 2023. Individuals with gynecologic cancer before or within six months of surgery were excluded. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards regression. Sensitivity analyses varied the time between surgery and cancer diagnosis to account for pre-existing serous tubal intraepithelial carcinomas. Results Among 196,839 individuals, 57,941 underwent OBS and 138,898 underwent comparator surgeries. 142 epithelial ovarian cancers were diagnosed (19 in the OBS group and 123 in the comparator surgery group). OBS was associated with reduced risk of any ovarian carcinoma, with an adjusted hazard ratio (aHR) of 0.60 (95% CI, 0.36 to 0.98). For serous ovarian carcinoma (high- and low-grade combined due to missing grade data), the aHR was 0.47 (95% CI, 0.22 to 0.99). Sensitivity analyses with 12- and 18-month intervals showed aHRs of 0.59 (95% CI, 0.35 to 0.99) and 0.60 (95% CI, 0.35 to 1.01) for all ovarian carcinomas, and 0.49 (95% CI, 0.23 to 1.01) and 0.47 (95% CI, 0.22 to 0.99) for serous ovarian carcinoma, respectively. Conclusions OBS was associated with reduced risk of ovarian carcinoma, supporting its role as a primary prevention strategy.

Abstract INTRODUCTION: Pleuropulmonary blastoma (PPB) and Sertoli-Leydig cell tumor (SLCT) are DICER1-related tumors for which novel therapies are urgently needed. A subset of Wilms tumors are also associated with germline or somatic variants in DICER1. Current therapies include cytotoxic chemotherapy, radiation, and surgery, but there are limited options for patients with recurrent disease. Antibody-Drug Conjugates (ADC) have emerged as promising therapies for several solid tumors. Aberrantly expressed cell surface proteins, including Preferentially Expressed Antigen in Melanoma (PRAME), represent potential targets for immunotherapeutic treatments like CAR-T cell and antibody-based therapies in malignant cancers, including DICER1-associated tumors. METHODS: Individuals diagnosed with PPB, SLCT, and Wilms tumor who enrolled in the International PPB/DICER1 Registry, International OTST Registry, and/or UT Southwestern Pediatric Hematology-Oncology Biorepository were selected for analysis. We analyzed ten PPB samples (four PDX, six primary tumor), four SLCT samples (all primary tumor), and 54 Wilms tumor samples (4 PDX, 50 primary tumor). DICER1 hotspot variants were verified in all 14 PPB and SLCT samples, while none of the Wilms tumor samples we analyzed exhibited DICER1 hotspot variants. Mapped and normalized whole-transcriptome sequencing reads were used to examine expression of 73 targets of antibody- or cell-based therapies that are clinically approved or under clinical investigation on clinicaltrials.gov. Genes with a median expression exceeding 2.5 transcripts per million (TPM) were considered expressed in a given tumor type; this threshold was selected to be permissive in identifying potential targets for further evaluation. RESULTS: Of the 73 genes of interest, 21 targetable cell-surface genes met a median expression threshold of 2.5 TPM in at least one tumor type: 11 genes in PPB, 16 in SLCT, and 14 in Wilms. Seven genes (FN1, PRAME, MCAM, CD248, IL11RA, CD276 (B7-H3), and MRC2) were expressed at this level in all three tumor types. Additional genes were expressed above this level in only two of the tumor types; PDGFRA in PPB and SLCT; GPC2 and TYRO3 in SLCT and Wilms tumor; and CSPG4, ERBB2, FZD10 in PPB and Wilms tumor. Six genes were exclusively expressed in SLCT (AXL, GPNMB, PROM1, KDR, ITGA6, FGFR4), and two were unique to Wilms tumor (GPC1, ULBP3). Of these, PRAME was previously reported as frequently expressed in DICER1-associated tumors; little has been reported about the remaining potential targets. CONCLUSION: PPB, SLCT, and Wilms tumor express several potential immunotherapy targets by RNA-seq. Expression of these potential targets should be investigated by immunostaining in a wider panel of tumors. Further study on the potential for ADCs or CAR-T cell therapies to treat DICER1-related conditions is needed. Citation Format: Brenya McNally, BS, Paige H.R. Mallinger, MS, David Huntsman, MD, FRCPC, FCCMG, Yemin Wang, PhD, Joyce Zhang, PhD, Claudette R. Fraire, PhD, Peter J. Schoettler, MD, Kris Ann P. Schultz, MD, Kenneth S. Chen, MD. Identifying potential cell-surface targets for therapeutic treatment of DICER1-related cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Breaking Barriers in the Fight against Rare Cancers; 2026 Jul 18-20; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(14_Suppl):Abstract nr A018.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Vaginal Cancer outline the recommended diagnostic workup, staging considerations, and treatment options for this rare malignancy. Because vaginal cancer is uncommon and shares many biologic and clinical characteristics with cervical cancer, several management recommendations, particularly systemic therapy, are extrapolated from evidence and practices established for cervical cancer. This guideline excerpt summarizes key components of management, including diagnostic evaluation and workup, principles of staging, pathology considerations, radiation therapy principles, and primary treatment recommendations for both early-stage and advanced disease. It also details approaches to manage relapses, including locoregional recurrence and distant metastases, and provides an in-depth overview of systemic therapy recommendations for vaginal cancer.

This cohort study evaluates the reduction in risk of high-grade serous carcinoma among women undergoing opportunistic bilateral salpingectomy in Canada.

The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Cervical Cancer provide diagnostic workup, staging, and various treatment recommendations for cervical cancer based on clinical and surgical staging. This selection from the NCCN Guidelines for cervical cancer specifically focuses on diagnosis and workup, principles of staging and surgery, and primary treatment recommendations for early-stage and advanced disease and provides a detailed overview of systemic therapy recommendations for cervical cancer.

Abstract BRCA-associated homologous recombination deficiency (HRD) is present in ~ 50% of high-grade serous carcinomas (HGSC) and predicts sensitivity to platinum-based therapy. However, there is little understanding of why some patients with BRCA-deficient tumors experience unexpectedly poor outcomes. We profiled 154 tumors, enriched for patients with BRCA-deficient tumors that experienced short overall survival (≤ 3 years, n = 42), using whole-genome, transcriptome, and methylation analyses. All but one BRCA-deficient tumor exceeded an accepted HRD genomic scarring threshold. However, patients with BRCA1-deficient HGSC with a more elevated HRD score survived significantly longer. Patients with BRCA2-deficient HGSC and loss of NF1 survived twice as long as those without NF1 loss, whereas PIK3CA or RAD21 amplification defined BRCA2-deficient HGSC with exceptionally short survival. BRCA1-deficient tumors in short survivors had evidence of immunosuppressive c-kit signaling and EMT. In a large HGSC cohort (n = 1,389) including 282 individuals with pathogenic germline BRCA variants (gBRCApv), the location of the mutation within functional domains stratified clinical outcomes. Notably, residual disease after primary surgery had limited prognostic effect in gBRCApv-carriers compared to non-carriers. Our findings indicate that tumor HR proficiency in the context of therapy response and survival is not a binary property, and highlight genomic and immune modifiers of outcomes in BRCA-deficient HGSC.

Abstract Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare, deadly form of ovarian cancer that uniformly harbors mutations in SMARCA4, a member of the SWI/SNF chromatin remodeling complex. SWI/SNF impacts RNA splicing, and dysregulation of splicing can generate immunogenic tumor antigens. Here, we explored the relationship between SMARCA4 loss and RNA splicing dysregulation. SCCOHT primary tumors harbored tumor-associated outlier splicing events compared to normal tissues. Many of the tumor events were retained introns encoding novel peptides predicted to bind to MHC-I complexes. Immune cells were observed in primary SCCOHT tumors, suggesting a potentially immune reactive tumor microenvironment. Mutations in several SWI/SNF subunits were associated with higher rates of outlier retained introns across tumor types in TCGA data. Interestingly, RNA sequencing of isogenic SCCOHT cell lines demonstrated a role for SMARCA4 in intron retention. Distinct protein-protein interactions between splicing factors identified in SCCOHT cell lines supported a role for SMARCA4 in splicing regulation. Further, SWI/SNF localized to genes which were differentially spliced. Mass spectrometry analyses confirmed expression of some of these novel peptides and a subset of these are predicted to bind to MHC-I complexes. A pool of these novel peptides derived from retained introns in SCCOHT triggered proliferation and expression of TNFa and INFb in primary human T cells. Together, these data suggest that SMARCA4 loss in SCCOHT leads to intron retention. Furthermore, T cell activation by novel peptides encoded by these tumor-specific splicing events suggests intron retention could be a source of tumor-associated antigens in SCCOHT. Citation Format: Elizabeth Raupach, Apurva Hegde, Krystine Garcia-Masnfield, Marice Alcantara, David Rose, Rebecca Halperin, Krystal Orlando, Jessica Lang, Ritin Sharma, Victoria David-Dirgo, Salvatore Facista, Rayvon Moore, Rochelle Kofman, Zoe Jensen, Victoria Zismann, Anthony Karnezis, Yemin Wang, Lynda Bennett, Timothy Whitsett, Marcin Kortylewski, William Hendricks, David Huntsman, Lorna Rodriguez-Rodriguez, Bernard Weissman, Jeffrey Trent, Patrick Pirrotte. Loss of SMARCA4 leads to intron retention and generation of tumor-associated antigens in small cell carcinoma of the ovary, hypercalcemic type [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B065.

Abstract Despite homologous recombination (HR) deficiency being an important predictor of survival in high-grade serous ovarian carcinoma (HGSC), its status is rarely considered in large-scale studies of prognostic signatures and biomarkers. We sought to develop a gene expression-based classifier of HR deficient (HRD) HGSCs, suitable for archival FFPE tumor samples, to determine whether established prognostic markers were dependent on HR status. Using 361 HGSCs from The Cancer Genome Atlas (TCGA) where HR status was defined by the genomic gold standard, a HRD score, we trained and tested a ridge penalized logistic regression model. This 218-gene mRNA expression signature was then applied in 6002 HGSCs from the Ovarian Tumor Tissue Analysis (OTTA) consortium to predict the probability of a sample being HRD. In this large cohort of FFPE samples, we sought to understand the relationship between HR and overall survival. Applying Kaplan-Meier analyses and multivariate Cox proportional hazard regression modelling, adjusting for age and stratified by stage and study, we examined the relationship between HR status and the PrOTYPE subtype, SPOT prognostic score and other known prognostic markers in HGSC. Our machine learning model was 84% accurate in a held-out subset of the TCGA (n=73). Of the 6002 OTTA HGSCs, 40.4% were predicted to be HRD. These cases were significantly younger, were enriched for early stage (FIGO I/II) and had improved outcomes when compared to HR proficient (HRP) cases (hazard ratio [HZR]=0.71, 95% confidence interval [CI]=0.66-0.76, p<2x10-16). A linear increase in survival time was observed as the probability of a sample being HRD increased. HGSCs with >75% likelihood of being HRD had a median 5-year survival of 49.3% (95%CI=46.2-52.6%) which was a 17.7% increase from those with <25% likelihood. Both PrOTYPE and SPOT were significantly associated with survival, independent of HR status (p<2x10-16 and p<2x10-16 respectively). Notably the probability of being HRD was negatively correlated with an unfavorable SPOT score (R=-0.32, p<2x10-16), suggesting that SPOT partially captures the survival advantage of HR deficiency. Several individual biomarkers, assessed in 1248 to 2858 cases, showed HR dependent survival associations. HRD HGSCs with high GMNN expression had significantly improved, long-term outcomes (4-10years, HZR=0.39, 95%CI=0.20-0.78, p=0.01), and may be a marker of exceptional survival, while AR negative HRD cases had poorer outcomes, earlier in disease progression (0-4years, HZR=1.43, 95%CI=1.03-1.98, p=0.03). Significantly poorer prognoses were observed in HRP cases expressing PTEN (HZR=1.39, 95%CI=1.04-1.87, p=0.03), and in HRD cases with high expression of MyD88 (HZR=1.21, 95%CI=1.01-1.45, p=0.04). RB1 and FOXJ1 protein expression, and CD8+ T cell abundance were prognostic irrespective of HR status. Our study contributes to understanding the association between HR and HGSC survival in a statistically powered cohort and demonstrates heterogeneity in outcomes through clinically relevant prognostic signatures and biomarkers. Citation Format: Ashley L. Weir, Derek Chiu, Aline Talhouk, Mike S. Anglesio, Dale W. Garsed, Anna DeFazio, Holly H. Harris, Joellen M. Schildkraut, Andrew Berchuck, Ellen L. Goode, Paul D.P. Pharoah, David Huntsman, David Bowtell, Jen A. Doherty, Nadia M. Davidson, Martin Köbel, Susan J. Ramus. Homologous recombination DNA repair dependent survival associations in high-grade serous ovarian carcinoma: an Ovarian Tumor Tissue Analysis consortium study [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B046.

Abstract Introduction: The purpose of this study is to evaluate the effectiveness of opportunistic salpingectomy (OS), a procedure that aims to remove only the fallopian tubes of general population risk women, for the prevention of epithelial ovarian cancer. Currently, the method of prevention for individuals at high risk of ovarian cancer involves a bilateral salpingo-oophorectomy (BSO), a procedure that removes both the fallopian tubes and ovaries. However, this procedure is not recommended for individuals of the general population, who make up about 80% of ovarian cancers, due to negative health implications to the cardiovascular and skeletal systems because of surgically induced menopause. The effectiveness of the OS in preventing ovarian cancers and how the procedure impacts the histotype distribution of ovarian cancers remains unknown. Study Methods: This study uses a population-based approach and a case-based approach to determine the effectiveness of OS and its impact on histotype distribution, respectively. For the population-based analysis, we will search through clinical databases to acquire cases of individuals who have had an OS and a tumor. A control population who have their fallopian tubes in-tact will also be acquired. A cox-proportional hazard analysis will be performed to determine the effectiveness of the procedure. Using pathological records, the case-based ascertainment of tumors from individuals who have had an OS will be selected and reviewed for histotype confirmation. Fallopian tubes of these patients will also be reviewed for precursor lesions. This cohort will be compared to a historical histotype distribution of ovarian cancers. Results: For the population-based approach, we have to date, identified less than five serous ovarian cancers in individuals who have had an OS (n=40, 477). A comparator surgery was used as a control and showed 21 cancers. For the case-based approach, we have partnered with 23 collaborating institutions from around the world to identify tumors in individuals who have had an OS. We have identified 26 epithelial ovarian cancers, with the most lethal gynecological histotype, high grade serous carcinoma (HGSC), accounting for 23.1% of the total proportion of epithelial ovarian cancer cases (n=6/26). This is significantly less than the historical histotype distribution of HGSC, which is 69.3% (Fisher’s exact test, p<0.0001). One HGSC case had a precursor lesion called a serous tubal intraepithelial carcinoma (STIC) while reviewing fallopian tubes of this individual. TP53 mutation analysis on one HGSC tumor sample showed a frameshift mutation in TP53 (c229fs) with the tumor and the corresponding STIC staining negative for p53 protein expression by immunohistochemistry. Conclusion: This evidence demonstrates the effectiveness of opportunistic salpingectomy for the prevention of ovarian cancer and shows a histotype distribution shift, with the most lethal gynecological malignancy having a significant reduction in cases following the procedure. Citation Format: Ramlogan Sowamber, Alice J. Mei, Paramdeep Kaur, Julianne McLeod, Emily McKay, Alex Lukey, Jamie Bakkum-Gamez, Natalia Buza, Paul Cohen, Kyle Devins, Rhonda Farrell, Christine Garcia, Blake Gilks, Ellen Goode, Anjelica Hodgson, Brooke Howitt, Pei Hui, Jutta Huvila, Anthony Karnezis, Kianoosh Keyhanian, Mary Kinloch, Martin Köbel, Felix KF. Kommoss, Lawrence Kushi, Janice S. Kwon, Kara Long-Roche, Anais Malpica, Jessica N. McAlpine, Dianne Miller, Esther Oliva, Andrea Palicelli, Aleksandra Paliga, Carlos Parra-Herran, Celeste Leigh Pearce, Sharnel Perera, Jurgen M. Piek, Haiyan Qiu, Joseph Rabban, Robert Rome, Miranda Steenbeek, Rebecca Stone, Aline Talhouk, Kristin M. Tischer, Britton Trabert, Penelope M. Webb, John R. Zalcberg, Gillian E. Hanley, David G. Huntsman. Evaluating the effectiveness of opportunistic salpingectomy (OS) for the prevention of epithelial ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B045.