A Retrospective Genomic Landscape of 661 Young Adult Glioblastomas Diagnosed Using 2016 WHO Guidelines for Central Nervous System Tumors.

The authors present a cohort of 661 young adult glioblastomas diagnosed using 2016 WHO World Health Organization Classification of Tumors of the Central Nervous System, utilizing comprehensive genomic profiling (CGP) to explore their genomic landscape and assess their relationship to currently defined disease entities. This analysis explored variants with evidence of pathogenic function, common copy number variants (CNVs), and several novel fusion events not described in literature. Tumor mutational burden (TMB) mutational signatures, anatomic location, and tumor recurrence are further explored. Using data collected from CGP, unsupervised machine-learning techniques were leveraged to identify 10 genomic classes in previously assigned young adult glioblastomas. The authors relate these molecular classes to current World Health Organization guidelines and reference current literature to give therapeutic and prognostic descriptions where possible.

Demographic disparities in children with retropharyngeal and parapharyngeal abscesses.

PURPOSE: To explore the impact that demographic and socioeconomic factors such as age, gender, race, and insurance status have on the diagnosis of retropharyngeal (RPA) and parapharyngeal abscesses (PPA) in the pediatric population. METHODS: The 2016 HCUP KID was searched for all RPA/PPA discharges using the joint ICD-10 code J39.0. Descriptive statistics, univariate, and multivariate analyses were performed to assess the relationship between demographic factors and their impact on RPA/PPA diagnosis. Results were reported with their corresponding odds ratio with a 95 % confidence interval and p-value. RESULTS: 56.4 per 100,000 weighted discharges were discharged with a diagnosis of a RPA/PPA, the average age was 5.7 years old, with a male predominance. Pediatric discharges diagnosed with a RPA/PPA were less likely to identify as Hispanic or Asian/Island Pacific. They were also less likely to be insured by Medicaid and reside in zip codes with a lower median income. CONCLUSION: The analysis of this national pediatric database demonstrated significant demographic differences in children diagnosed with RPA/PPAs. Following the multivariate analysis, children from a higher socioeconomic background and those with private insurance were more likely to be diagnosed with a RPA/PPAs. However, disparities in children's overall hospital course and complications is a potential area for future research.

Relationship between otolaryngology interest groups and residency match results.

BACKGROUND: Many students have limited exposure to otolaryngology-head and neck surgery (OTOHNS) throughout medical school, limiting recruitment of medical students early in their medical careers. OBJECTIVE: To assess the association between otolaryngology interest groups (OIGs) at medical schools and percentage of students matching into OTOHNS residency programs. To characterize specific aspects of OIGs that may impact the percentage of students matching into OTOHNS residency programs from a given medical school. METHODS: Data was obtained from web searches of 141 accredited U.S. allopathic medical schools to see if they possessed OIGs. Information on the various activities and opportunities that OIGs participated in was collected through medical school websites. 2020 NRMP® match results data were obtained. RESULTS: Web searches found that 73 % (103 out of 141) of U.S. allopathic medical schools have OIGs. Medical schools with OIGs were associated with a 35 % increase in the median percentage of OTOHNS matches (P = 0.022). Of the 103 medical schools with OIGs, 53 % (55) of the schools had information on their websites describing activities and opportunities that their OIGs participate in. OIGs with research and/or mentorship opportunities were associated with increases in OTOHNS matches by 32 % (P = 0.043) and 83 % (P = 0.012), respectively. CONCLUSION: The presence of an OIG at a medical school is associated with an increased percentage of students matching into OTOHNS from that medical school. OIGs that provide research or mentorship opportunities are associated with an increased percentage of students matching into OTOHNS from those medical schools.

Assessing Loss to Follow-up After Newborn Hearing Screening in the Neonatal Intensive Care Unit: Sociodemographic Factors That Affect Completion of Initial Audiological Evaluation.

OBJECTIVES: Neonatal intensive care unit (NICU) patients are at high risk for congenital hearing loss. Previous studies have found sociodemographic factors associated with loss to follow-up for newborn hearing screening, but none have specifically studied the NICU population. Our objective is to determine if demographics and socioeconomic status is associated with loss to follow-up in a newborn population with extended NICU stay. DESIGN: A retrospective cohort study was conducted on 443 NICU infants with extended NICU stay utilizing data extracted from infant and maternal medical records at an urban safety-net hospital. RESULTS: Younger maternal age (adjusted odds ratio [OR] 0.95, confidence interval [CI] 0.91 to 0.99), higher gravidity (adjusted OR 1.39, CI 1.12 to 1.72), and former smoking status (adjusted OR 2.57, CI 1.07-6.18) were identified as independent predictors of loss to follow-up for NHS after conducting a multivariable logistic regression. Demographic and socioeconomic variables, such as sex, parity, birth weight, mode of birth, highest level of maternal education, maternal race/ethnicity, zip code metrics, and maternal language were not found to be associated with loss to follow-up. CONCLUSIONS: Maternal age, gravidity, and smoking status are risk factors for loss to follow-up for NHS in newborns with extended NICU stay, a group at high risk for hearing loss. Our findings demonstrate that socioeconomic and demographic factors for loss to follow-up in the extended-stay NICU population are distinct from the well-baby population. Further investigation of these patients will allow prioritization of limited resources to subgroups within the extended-stay NICU population at risk for loss to follow-up for newborn hearing screening.

Internet and social media research by parents of pediatric otolaryngologic patients.

PURPOSE: Public access to medical information has increased dramatically with the growth and accessibility of the Internet. The goal of this study is to characterize how parents use the Internet to understand and make decisions about their child's otolaryngologic surgery. MATERIALS AND METHODS: A survey was distributed to parents of pediatric patients undergoing otolaryngologic procedures to assess if and how parents gather information about their child's surgery. RESULTS: 105 parents completed the survey. 59.4% of parents gathered online information about their child's surgery. 86% of these parents used Google, 36% used YouTube, 16% used Wikipedia, and 9% used a hospital website. Most searched for general information about the surgery, followed by risks, pain/recovery, and specifics about the surgery. 69% reported that the information found influenced the healthcare decisions they made for their child. 86% felt the information was trustworthy. 21% discussed the information with their child's surgeon. 17% gathered information about their child's surgeon, of which 73% were interested in the surgeon's experience. 69% reported this influenced their choice of surgeon. CONCLUSIONS: Most parents of pediatric otolaryngologic patients use the Internet to gather information about their child's surgery, view that information as accurate, and use that information to make healthcare decisions. However, less than one quarter of parents discuss the information with their child's surgeon. It is critical to understand how parents use the Internet for healthcare information so otolaryngologists can better direct their patients' parents to appropriate and accurate resources.

The utility of ThyroSeq® in the management of indeterminate thyroid nodules by fine-needle aspiration.

OBJECTIVE: We aim to evaluate the impact of ThyroSeq® in the management of indeterminate thyroid nodules (ITN), including Bethesda III and IV nodules. METHODS: ITNs that underwent ThyroSeq testing between 2016 and 2019 were retrospectively reviewed. A control cohort included ITNs without molecular testing. Cytological, molecular, and histological data were collected. RESULTS: We identified 202 ITNs that underwent molecular testing (128 in Bethesda III and 74 in Bethesda IV). Mutations were found in 58 nodules with mutation rates of 21.9% in Bethesda III and 40.5% in Bethesda IV. In this cohort, 49 cases had surgical resection with a resection rate of 24.3% (49/202, 15.6% in Bethesda III and 39.2% in Bethesda IV). Among the resected cases, 42 cases had positive molecular results. Thyroid cancer was diagnosed in 21 nodules with a malignancy detection rate of 10.4%. In the other cohort, we identified 236 ITNs (158 in Bethesda III and 78 in Bethesda IV). Surgical resection was performed in 127 cases, with a resection rate of 53.8% (127/236, 46.2% in Bethesda III and 69.2% in Bethesda IV). Thyroid cancer was diagnosed in 21 nodules, with a malignancy detection rate of 8.9%. The risk of malignancy (ROM) recalculated based on positive ThyroSeq results was significantly higher (21.4%-35.5% in Bethesda III and 50%-60% in Bethesda IV) than that without molecular testing (4.4%-9.6% in Bethesda III and 17.9%-25.9% in Bethesda IV). CONCLUSION: We concluded that ThyroSeq significantly decreased the surgical resection rate (from 53.8% to 24.3%) without significantly affecting the malignancy detection rate in ITNs. Furthermore, positive molecular testing significantly increased ROM in ITNs. We believe that the recalculated ROM should be incorporated into the management of ITNs.

Biomarkers in Breast Cancer: An Integrated Analysis of Comprehensive Genomic Profiling and PD-L1 Immunohistochemistry Biomarkers in 312 Patients with Breast Cancer.

BACKGROUND: We examined the current biomarker landscape in breast cancer when programmed death-ligand 1 (PD-L1) testing is integrated with comprehensive genomic profiling (CGP). MATERIAL AND METHODS: We analyzed data from samples of 312 consecutive patients with breast carcinoma tested with both CGP and PD-L1 (SP142) immunohistochemistry (IHC) during routine clinical care. These samples were stratified into hormone receptor positive (HR+)/human epidermal growth factor receptor negative (HER2-; n = 159), HER2-positive (n = 32), and triple-negative breast cancer (TNBC) cohorts (n = 121). RESULTS: We found that in the TNBC cohort, 43% (52/121) were immunocyte PD-L1-positive, and in the HR+/HER2- cohort, 30% (48/159) had PIK3CA companion diagnostics mutations, and hence were potentially eligible for atezolizumab plus nab-paclitaxel or alpelisib plus fulvestrant, respectively. Of the remaining 212 patients, 10.4% (22/212) had a BRCA1/2 mutation, which, if confirmed by germline testing, would allow olaparib plus talazoparib therapy. Of the remaining 190 patients, 169 (88.9%) were positive for another therapy-associated marker or a marker that would potentially qualify the patient for a clinical trial. In addition, we examined the relationship between immunocyte PD-L1 positivity and different tumor mutation burden (TMB) cutoffs and found that when a TMB cutoff of ≥9 mutations per Mb was applied (cutoff determined based on prior publication), 11.6% (14/121) patients were TMB ≥9 mutations/Mb and of these, TMB ≥9 mutations per Mb, 71.4% (10/14) were also positive for PD-L1 IHC. CONCLUSION: Our integrated PD-L1 and CGP methodology identified 32% of the tested patients as potentially eligible for at least one of the two new Food and Drug Administration approved therapies, atezolizumab or alpelisib, and an additional 61.2% (191/312) had other biomarker-guided potential therapeutic options. IMPLICATIONS FOR PRACTICE: This integrated programmed death-ligand 1 immunohistochemistry and comprehensive genomic profiling methodology identified 32% of the tested patients as eligible for at least one of the two new Food and Drug Administration-approved therapies, atezolizumab or alpelisib, and an additional 61.2% (191/312) had other biomarker-guided potential therapeutic options. These findings suggest new research opportunities to evaluate the predictive utility of other commonly seen PIK3CA mutations in hormone receptor-positive breast cancers and to standardize tumor mutation burden cutoffs to evaluate its potentially predictive role in triple-negative breast cancer.

Robot-assisted epiglottopexy as a method for managing adult obstructive sleep apnea.

INTRODUCTION: Patients who do not tolerate continuous positive airway pressure (CPAP) for treatment of obstructive sleep apnea (OSA) often seek surgical management. A variety of procedures exist to address the nasal passages, oropharynx, hypopharynx, and larynx. Diagnostic studies including drug-induced sleep endoscopy (DISE) are helpful in identifying areas of obstruction. One potential site of obstruction is at the level of the epiglottis. We describe the use of robotic technology to assist with epiglottopexy to manage epiglottic retroflexion as a cause of two patients' OSA. This is the first reported robot-assisted epiglottopexy in the adult otolaryngology literature. METHODS: This is a case series of two patients with OSA who demonstrated epiglottis collapse into the airway during DISE. They were evaluated by polysomnographic testing (PSG), Epworth Sleepiness Scale (ESS), and physical exam. Given their epiglottic collapse seen on DISE, they underwent robot-assisted epiglottopexy. RESULTS: Both patients had moderate to severe OSA preoperatively. They successfully underwent robot-assisted epiglottopexy as a surgical intervention. They tolerated the procedure, and there have been no complications. Each reported improved symptoms, with patient one showing a decrease in total AHI and a substantial decrease in oxygen desaturations at night. The second patient reported a significant decrease in AHI and ESS. CONCLUSION: There are many options for surgical intervention in patients with OSA. Epiglottopexy is one method for addressing collapse of the epiglottis and can be achieved successfully through robot-assisted epiglottopexy in adult patients with OSA. LEVEL OF EVIDENCE: IV.

Improving Cancer Diagnosis and Care: Patient Access to High-Quality Oncologic Pathology.

Drawing on discussions at a workshop hosted by the National Cancer Policy Forum, current challenges in pathology are reviewed and practical steps to facilitate high­quality cancer diagnosis and care through improved patient access to expertise in oncologic pathology are highlighted.

Genomic Landscape of Adult and Pediatric BCR-ABL1-Like B-Lymphoblastic Leukemia Using Parallel DNA and RNA Sequencing.

BCR-ABL1-like B-Acute Lymphoblastic Leukemia (B-ALL) is a subset of B-ALL with a poor prognosis that is found in all age groups. Definitive identification of these patients is difficult in routine clinical practice as gene expression profiling, the gold standard test, is not widely available. Comprehensive genomic profiling performed on 450 patients with extensive fusion profiling revealed a wide range of genomic alterations which were consistent with a classification of BCR-ABL1-like B-ALL in 29% of cases. This manuscript highlights a clinically available alternative method for identifying a large subset of patients with BCR-ABL1-like B-ALL.

Loss of LARGE2 disrupts functional glycosylation of α-dystroglycan in prostate cancer.

Dystroglycan (DG) is a cell surface receptor for extracellular matrix proteins and is involved in cell polarity, matrix organization, and mechanical stability of tissues. Previous studies documented loss of DG protein expression and glycosylation in a variety of cancer types, but the underlying mechanisms and the functional consequences with respect to cancer progression remain unclear. Here, we show that the level of expression of the ßDG subunit as well as the glycosylation status of the αDG subunit inversely correlate with the Gleason scores of prostate cancers; furthermore, we show that the functional glycosylation of αDG is substantially reduced in prostate cancer metastases. Additionally, we demonstrate that LARGE2 (GYLTL1B), a gene not previously implicated in cancer, regulates functional αDG glycosylation in prostate cancer cell lines; knockdown of LARGE2 resulted in hypoglycosylation of αDG and loss of its ability to bind laminin-111 while overexpression restored ligand binding and diminished growth and migration of an aggressive prostate cancer cell line. Finally, our analysis of LARGE2 expression in human cancer specimens reveals that LARGE2 is significantly down-regulated in the context of prostate cancer, and that its reduction correlates with disease progression. Our results describe a novel molecular mechanism to account for the commonly observed hypoglycosylation of αDG in prostate cancer.

Dependence of castration-resistant prostate cancer (CRPC) stem cells on CRPC-associated fibroblasts.

We previously established a role for cancer-associated fibroblasts (CAF) in enhancing the self-renewal and differentiation potentials of putative prostate cancer stem cells (CSC). Our published work focused on androgen-dependent prostate cancer (ADPC) using the conditional Pten deletion mouse model. Employing the same model, we now describe the interaction of CAF and CSC in castration-resistant prostate cancer (CRPC). CAF isolated from ADPC (ADPCAF) and from CRPC (CRPCAF) were compared in terms of their ability to support organoid formation and tumor initiation by CSC from CRPC (CRPCSC) in vitro and in vivo. CRPCSC formed spheroids in vitro and well-differentiated glandular structures under the renal capsules of recipient mice in vivo more effectively in the presence of CRPCAF compared to ADPCAF. Furthermore, whereas CSC with CAF from ADPC formed mostly well-differentiated tumors in our previous study, we now show that CRPCSC, when combined with CRPCAF (but not ADPCAF), can form aggressive, poorly-differentiated tumors. The potential of CRPCAF to support organoid/tumor formation by CRPCSC remained greater even when compared to 10-fold more ADPCAF, suggesting that paracrine factors produced specifically by CRPCAF preferentially potentiate the stemness and tumorigenic properties of the corresponding CSC. This apparently unique property of CRPCAF was notable when the CAF and CSC were grafted in either intact or castrated recipient mice. In both environments, CRPCAF induced in the epithelial compartment higher proliferative activity compared to ADPCAF, indicated by a higher Ki67 index. Factors released by CRPCAF to regulate CRPCSC may be targeted to develop novel therapeutic approaches to manage advanced prostate cancer.

Advances in the Use of Hypoglossal Nerve Stimulator in Adolescents With Down Syndrome and Persistent Obstructive Sleep Apnea-A Systematic Review.

INTRODUCTION: The Hypoglossal Nerve Stimulator (HNS) is a novel therapy that has been extensively studied in adults and more recently, it has been incorporated in children with Down Syndrome (DS) with persistent obstructive sleep apnea after adenotonsillectomy and trial of continuous positive airway pressure treatment. This systematic review article aims to examine the existing literature on HNS use in children to explore the benefits, efficacy, and parental experiences. METHODS: MEDLINE, Web of Science and EMBASE were searched to include all studies published up to March 2nd, 2023, on the topic of HNS use in pediatric population under 21 years old. RESULTS: A total of 179 studies were initially identified from which 10 articles were consistent with the inclusion criteria. Nine articles addressed outcomes after implantation of the HNS device in children with DS and 1 article explored the parental experiences. Findings were similar across studies where after implantation of HNS, there was marked improvement in polysomnographic outcomes and quality of life scores with high level of compliance. CONCLUSIONS: HNS holds promise as an effective treatment option for pediatric patients with DS and persistent OSA after AT and CPAP trials. It significantly improves sleep-disordered breathing, quality of life, and neurocognitive measures, leading to substantial and sustained benefits for these children. While the findings are encouraging, further research is needed to explore the potential of HNS in other pediatric populations without DS and to raise awareness among healthcare providers about this treatment option. Overall, HNS may offer significant long-term benefits for the overall well-being and health of pediatric patients with DS and persistent OSA.

Assessing ChatGPT's Responses to Otolaryngology Patient Questions.

OBJECTIVE: This study aims to evaluate ChatGPT's performance in addressing real-world otolaryngology patient questions, focusing on accuracy, comprehensiveness, and patient safety, to assess its suitability for integration into healthcare. METHODS: A cross-sectional study was conducted using patient questions from the public online forum Reddit's r/AskDocs, where medical advice is sought from healthcare professionals. Patient questions were input into ChatGPT (GPT-3.5), and responses were reviewed by 5 board-certified otolaryngologists. The evaluation criteria included difficulty, accuracy, comprehensiveness, and bedside manner/empathy. Statistical analysis explored the relationship between patient question characteristics and ChatGPT response scores. Potentially dangerous responses were also identified. RESULTS: Patient questions averaged 224.93 words, while ChatGPT responses were longer at 414.93 words. The accuracy scores for ChatGPT responses were 3.76/5, comprehensiveness scores were 3.59/5, and bedside manner/empathy scores were 4.28/5. Longer patient questions did not correlate with higher response ratings. However, longer ChatGPT responses scored higher in bedside manner/empathy. Higher question difficulty correlated with lower comprehensiveness. Five responses were flagged as potentially dangerous. CONCLUSION: While ChatGPT exhibits promise in addressing otolaryngology patient questions, this study demonstrates its limitations, particularly in accuracy and comprehensiveness. The identification of potentially dangerous responses underscores the need for a cautious approach to AI in medical advice. Responsible integration of AI into healthcare necessitates thorough assessments of model performance and ethical considerations for patient safety.

Re-evaluation of the methodology for estimating the US specialty physician workforce.

Increasing pursuit of subspecialized training has quietly revolutionized physician training, but the potential impact on physician workforce estimates has not previously been recognized. The Physicians Specialty Data Reports of the Association of American Medical Colleges, derived from specialty designations in the American Medical Association (AMA) Physician Professional Data (PPD), are the reference source for US physician workforce estimates; by 2020, the report for pathologists was an undercount of 39% when compared with the PPD. Most of the difference was due to the omission of pathology subspecialty designations. The rest resulted from reliance on only the first of the AMA PPD's 2 specialty data fields. Placement of specialty designation in these 2 fields is sensitive to sequence of training and is thus affected by multiple or intercalated (between years of residency training) fellowships. Both these phenomena have become progressively more common and are not unique to pathology. Our findings demonstrate the need to update definitions and methodology underlying estimates of the US physician workforce for pathology and suggest a like need in other specialties affected by similar trends.

Phase II open label, multi-center clinical trial of modulation of intermediate endpoint biomarkers by 1α-hydroxyvitamin D2 in patients with clinically localized prostate cancer and high grade pin.

BACKGROUND: Prostate cancer is the most common malignancy and second leading cause of cancer related deaths in American men supporting the study of prostate cancer chemoprevention. Major risk factors for this disease have been associated with low serum levels of vitamin D. Here, we evaluate the biologic activity of a less calcemic vitamin D analog 1α-hydroxyvitamin D2 [1α-OH-D2] (Bone Care International, Inc.) in patients with prostate cancer and high grade prostatic intraepithelial neoplasia (HG PIN). METHODS: Patients with clinically organ-confined prostate cancer and HG PIN were randomized to 1α-OH-D2 versus placebo for 28 days prior to radical prostatectomy. Intermediate endpoint biomarkers included serum vitamin D metabolites, TGFß 1/2, free/total PSA, IGF-1, IGFBP-3, bFGF, and VEGF. Tissue endpoints included histology, MIB-1 and TUNEL staining, microvessel density and factor VIII staining, androgen receptor and PSA, vitamin D receptor expression and nuclear morphometry. RESULTS: The 1α-OH-D2 vitamin D analog was well tolerated and could be safely administered with good compliance and no evidence of hypercalcemia over 28 days. While serum vitamin D metabolite levels only slightly increased, evidence of biologic activity was observed with significant reductions in serum PTH levels. TGF-ß2 was the only biomarker significantly altered by vitamin D supplementation. Whether reduced TGF-ß2 levels in our study is an early indicator of response to vitamin D remains unclear. CONCLUSIONS: While further investigation of vitamin D may be warranted based on preclinical studies, results of the present trial do not appear to justify evaluation of 1α-OH-D2 in larger clinical prostate cancer prevention studies.

Strong Job Market for Pathologists: Results From the 2021 College of American Pathologists Practice Leader Survey.

CONTEXT.­: There has long been debate about whether and when there may be a shortage of pathologists in the United States. One way to assess this is to survey the hiring experiences of pathology practices. A 2018 survey revealed a strong demand for pathologists, with expectations of continued strength. This study updates that prior analysis using data from a 2021 survey of pathology practice leaders. OBJECTIVE.­: To assess the US pathologist job market and examine implications. DESIGN.­: We analyzed data from the 2021 College of American Pathologists Practice Leader Survey. This survey queried practice leaders, including regarding the hiring of pathologists, the level of experience being sought, success in filling positions, and expectations for hiring in the next 3 years. RESULTS.­: Among the 375 surveyed practice leaders (about one-third of all US pathology practices), 282 provided information about pathologist hiring in 2021. A total of 157 of these 282 practices (55.7%) sought to hire at least 1 pathologist in 2021, up from 116 of 256 practices (45.3%) in 2017; the mean number of pathologists hired per practice also increased. In 2021, a total of 175 of 385 positions (45.5%) were to fill new positions, compared with 95 of 249 positions (38.2%) in 2017. Most practice leaders were comfortable hiring pathologists with less than 2 years of posttraining experience. Practice leaders anticipated continued strong demand for hiring pathologists during the next 3 years. CONCLUSIONS.­: Our analysis confirms that the demand in pathologist hiring is strong and much increased from 2017. We believe, in combination with other job market indicators, that demand may outstrip the supply of pathologists, which is limited by the number of trainees and has remained constant during the past 20 years.

Slow disease progression in a C57BL/6 pten-deficient mouse model of prostate cancer.

Prostate-specific deletion of Pten in mice has been reported to recapitulate histological progression of human prostate cancer. To improve on this model, we introduced the conditional ROSA26 luciferase reporter allele to monitor prostate cancer progression via bioluminescence imaging and extensively backcrossed mice onto the albino C57BL/6 genetic background to address variability in tumor kinetics and to enhance imaging sensitivity. Bioluminescence signal increased rapidly in Pten(p-/-) mice from 3 to 11 weeks, but was much slower from 11 to 52 weeks. Changes in bioluminescence signal were correlated with epithelial proliferation. Magnetic resonance imaging revealed progressive increases in prostate volume, which were attributed to excessive fluid retention in the anterior prostate and to expansion of the stroma. Development of invasive prostate cancer in 52-week-old Pten(p-/-) mice was rare, indicating that disease progression was slowed relative to that in previous reports. Tumors in these mice exhibited a spontaneous inflammatory phenotype and were rapidly infiltrated by myeloid-derived suppressor cells. Although Pten(p-/-) tumors responded to androgen withdrawal, they failed to exhibit relapsed growth for up to 1 year. Taken together, these data identify a mild prostate cancer phenotype in C57BL/6 prostate-specific Pten-deficient mice, reflecting effects of the C57BL/6 genetic background on cancer progression. This model provides a platform for noninvasive assessment of how genetic and environmental risk factors may affect disease progression.