PSMA-Avid Desmoid Tumor of the Abdominal Wall on 18F-Piflufolastat PET/CT.

ABSTRACT: Prostate-specific membrane antigen (PSMA) PET/CT is widely used in the evaluation of suspected metastasis for initial definitive therapy and suspected recurrence of prostate cancer. We outline a case report of a 62-year-old man with history of prostate cancer treated with surgery, salvage radiation, and hormonal therapy presenting with rising PSA levels. There was incidental detection of a PSMA-avid subcutaneous abdominal wall mass on PSMA PET/CT study, which was consistent with desmoid fibromatosis on an ultrasound-guided biopsy.

Detection of Adenocarcinoma of the Colon on 18 F-Fluciclovine PET/CT.

ABSTRACT: An 85-year-old man with prostate cancer and de novo bone metastases was treated with hormonal therapy with resolution of bone lesions, improved primary disease, and improved serum tumor markers. Although on hormonal therapy, biochemical recurrence prompted performance of 18 F-fluciclovine PET/CT. Fluciclovine PET/CT revealed primary prostate cancer progression with incidental note of avid foci in the colon for which colonoscopy was recommended. Colonoscopy with biopsy was performed with pathology revealing primary colon adenocarcinoma. Before reinitiation of prostate cancer therapy, segmental colon resection was performed with pathology positive for additional sites of colon cancer.

Surgical Management and Considerations for Patients with Localized High-Risk Prostate Cancer.

OPINION STATEMENT: Localized high-risk (HR) prostate cancer (PCa) is a heterogenous disease state with a wide range of presentations and outcomes. Historically, non-surgical management with radiotherapy and androgen deprivation therapy was the treatment option of choice. However, surgical resection with radical prostatectomy (RP) and pelvic lymph node dissection (PLND) is increasingly utilized as a primary treatment modality for patients with HRPCa. Recent studies have demonstrated that surgery is an equivalent treatment option in select patients with the potential to avoid the side effects from androgen deprivation therapy and radiotherapy combined. Advances in imaging techniques and biomarkers have also improved staging and patient selection for surgical resection. Advances in robotic surgical technology grant surgeons various techniques to perform RP, even in patients with HR disease, which can reduce the morbidity of the procedure without sacrificing oncologic outcomes. Clinical trials are not only being performed to assess the safety and oncologic outcomes of these surgical techniques, but to also evaluate the role of surgical resection as a part of a multimodal treatment plan. Further research is needed to determine the ideal role of surgery to potentially provide a more personalized and tailored treatment plan for patients with localized HR PCa.

Treatment Outcomes in Patients With Metastatic Renal Cell Carcinoma With Sarcomatoid and/or Rhabdoid Dedifferentiation After Progression on Immune Checkpoint Therapy.

BACKGROUND: Metastatic RCC with sarcomatoid and/or rhabdoid (S/R) dedifferentiation is an aggressive disease associated with improved response to immune checkpoint therapy (ICT). The outcomes of patients treated with VEGFR-targeted therapies (TT) following ICT progression have not been investigated. PATIENTS AND METHODS: Retrospective review of 57 patients with sarcomatoid (S), rhabdoid (R), or sarcomatoid plus rhabdoid (S + R) dedifferentiation who received any TT after progression on ICT at an academic cancer center. Clinical endpoints of interest included time on TT, overall survival (OS) from initiation of TT, and objective response rate (ORR) by RECIST version 1.1. Multivariable models adjusted for epithelial histology, IMDC risk, prior VEGFR TT, and inclusion of cabozantinib in the post-ICT TT regimen. RESULTS: 29/57 patients had S dedifferentiation and 19 had R dedifferentiation. The most frequently used TT was cabozantinib (43.9%) followed by selective VEGFR TT (22.8%). The median time on TT was 6.4 months for all, 6.1 months for those with S dedifferentiation, 15.6 months for R dedifferentiation, and 6.1 months for S + R dedifferentiation. Median OS from initiation of TT was 24.9 months for the entire cohort, and the ORR was 20.0%. Patients with R dedifferentiation had significantly longer time on TT than those with S dedifferentiation (HR 0.44, 95% CI, 0.21-0.94). IMDC risk was associated with OS. CONCLUSIONS: A subset of patients with S/R dedifferentiation derive clinical benefit from TT after they have progressive disease on ICT. Patients with R dedifferentiation appeared to derive more benefit from TT than those with S dedifferentiation.

Diagnostic Performance and Safety of Positron Emission Tomography with 18F-rhPSMA-7.3 in Patients with Newly Diagnosed Unfavourable Intermediate- to Very-high-risk Prostate Cancer: Results from a Phase 3, Prospective, Multicentre Study (LIGHTHOUSE).

BACKGROUND: Radiohybrid (rh) 18F-rhPSMA-7.3 is a novel high-affinity prostate-specific membrane antigen (PSMA)-targeting radiopharmaceutical for prostate cancer (PCa) imaging. OBJECTIVE: To evaluate the diagnostic performance and safety of 18F-rhPSMA-7.3 in newly diagnosed PCa patients planned for prostatectomy. DESIGN, SETTING, AND PARTICIPANTS: Data on 18F-rhPSMA-7.3 were reported from the phase 3 prospective, multicentre LIGHTHOUSE study (NCT04186819). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Patients underwent positron emission tomography/computed tomography (PET/CT) 50-70 min after an injection of 296 MBq 18F-rhPSMA-7.3. Images were interpreted locally and by three blinded independent readers. The coprimary endpoints were patient-level sensitivity and specificity for the detection of pelvic lymph node (PLN) metastases, validated using histopathology at PLN dissection. Prespecified statistical thresholds (lower bounds of 95% confidence interval [CI]) were set at 22.5% for sensitivity and 82.5% for specificity. RESULTS AND LIMITATIONS: Of 372 patients screened, 352 had evaluable 18F-rhPSMA-7.3-PET/CT and 296 (99 [33%] with unfavourable intermediate-risk [UIR] and 197 [67%] with high-/very-high-risk [VHR] PCa) subsequently underwent surgery. As per the independent reads, 23-37 (7.8-13%) patients had 18F-rhPSMA-7.3-positive PLN. Seventy (24%) patients had one or more positive PLNs on histopathology. The sensitivity for PLN detection was 30% (95% CI, 19.6-42.1%) for reader 1, 27% (95% CI, 17.2-39.1%) for reader 2, and 23% (95% CI, 13.7-34.4%) for reader 3, not meeting the prespecified threshold. Specificity was 93% (95% CI, 88.8-95.9%), 94% (95% CI, 89.8-96.6%), and 97% (95% CI, 93.7-98.7%), respectively, exceeding the threshold for all readers. Specificity was high (≥92%) across both risk stratifications. Sensitivity was higher among high-risk/VHR (24-33%) than among UIR (16-21%) patients. Extrapelvic (M1) lesions were reported for 56-98/352 (16-28%) patients who underwent 18F-rhPSMA-7.3-PET/CT irrespective of surgery. Verification of these (predominantly by conventional imaging) gave a verified detection rate of 9.9-14% (positive predictive value, 51-63%). No serious adverse events were observed. CONCLUSIONS: Across all risk stratifications, 18F-rhPSMA-7.3-PET/CT had high specificity, meeting the specificity endpoint. The sensitivity endpoint was not met, although higher sensitivity was noted among high-risk/VHR than among UIR patients. Overall, 18F-rhPSMA-7.3-PET/CT was well tolerated, and identified N1 and M1 disease prior to surgery in newly diagnosed PCa patients. PATIENT SUMMARY: In order to select the most appropriate treatment for patients with prostate cancer, it is critical to diagnose the disease burden accurately at initial diagnosis. In this study, we investigated a new diagnostic imaging agent in a large population of men with primary prostate cancer. We found it to have an excellent safety profile and to provide clinically useful information regarding the presence of disease beyond the prostate.

ACR Appropriateness Criteria® Soft Tissue Masses: 2022 Update.

Imaging should be performed in patients with a suspected soft tissue mass that cannot be clinically confirmed as benign. Imaging provides essential information necessary for diagnosis, local staging, and biopsy planning. Although the modalities available for imaging of musculoskeletal masses have undergone progressive technological advancements in recent years, their overall purpose in the setting of a soft tissue mass remains unchanged. This document identifies the most common clinical scenarios related to soft tissue masses and the most appropriate imaging for their assessment on the basis of the current literature. It also provides general guidance for those scenarios that are not specifically addressed. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Workup of Noncerebral Systemic Arterial Embolic Source.

Noncerebral systemic arterial embolism, which can originate from cardiac and noncardiac sources, is an important cause of patient morbidity and mortality. When an embolic source dislodges, the resulting embolus can occlude a variety of peripheral and visceral arteries causing ischemia. Characteristic locations for noncerebral arterial occlusion include the upper extremities, abdominal viscera, and lower extremities. Ischemia in these regions can progress to tissue infarction resulting in limb amputation, bowel resection, or nephrectomy. Determining the source of arterial embolism is essential in order to direct treatment decisions. This document reviews the appropriateness category of various imaging procedures available to determine the source of the arterial embolism. The variants included in this document are known arterial occlusion in the upper extremity, lower extremity, mesentery, kidneys, and multiorgan distribution that are suspected to be of embolic etiology. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Chronic Shoulder Pain: 2022 Update.

Chronic shoulder pain is an extremely common presenting complaint. Potential pain generators include the rotator cuff tendons, biceps tendon, labrum, glenohumeral articular cartilage, acromioclavicular joint, bones, suprascapular and axillary nerves, and the joint capsule/synovium. Radiographs are typically the initial imaging study obtained in patients with chronic shoulder pain. Further imaging may often be required, with modality chosen based on patient symptoms and physical examination findings, which may lead the clinician to suspect a specific pain generator. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Chronic Elbow Pain.

Chronic elbow pain can be osseous, soft tissue, cartilaginous, and nerve related in etiology. Imaging plays an important role in differentiating between these causes of chronic elbow pain. This document provides recommendations for imaging of chronic elbow pain in adult patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Staging and Follow-Up of Esophageal Cancer.

This document provides recommendations regarding the role of imaging in the staging and follow-up of esophageal cancer. For initial clinical staging, locoregional extent and nodal disease are typically assessed with esophagogastroduodenoscopy and esophageal ultrasound. FDG-PET/CT or CT of the chest and abdomen is usually appropriate for use in initial clinical staging as they provide additional information regarding distant nodal and metastatic disease. The detection of metastatic disease is critical in the initial evaluation of patients with esophageal cancer because it will direct patients to a treatment pathway centered on palliative radiation rather than surgery. For imaging during treatment, particularly neoadjuvant chemotherapy, FDG-PET/CT is usually appropriate, because some studies have found that it can provide information regarding primary lesion response, but more importantly it can be used to detect metastases that have developed since the induction of treatment. For patients who have completed treatment, FDG-PET/CT or CT of the chest and abdomen is usually appropriate for evaluating the presence and extent of metastases in patients with no suspected or known recurrence and in those with a suspected or known recurrence. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Imaging of Facial Trauma Following Primary Survey.

Maxillofacial trauma patients comprise a significant subset of patients presenting to emergency departments. Before evaluating for facial trauma, an emergency or trauma physician must perform a primary survey to ensure patient stabilization. Following this primary survey, this document discusses the following clinical scenarios for facial trauma: tenderness to palpation or contusion or edema over frontal bone (suspected frontal bone injury); pain with upper jaw manipulation or pain overlying zygoma or zygomatic deformity or facial elongation or malocclusion or infraorbital nerve paresthesia (suspected midface injury); visible nasal deformity or palpable nasal deformity or tenderness to palpation of the nose or epistaxis (suspected nasal bone injury); and trismus or malocclusion or gingival hemorrhage or mucosal hemorrhage or loose teeth or fractured teeth or displaced teeth (suspected mandibular injury). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

18F-Fluciclovine versus PSMA PET Imaging in Primary Tumor Detection during Initial Staging of High-Risk Prostate Cancer: A Systematic Review and Meta-Analysis.

Purpose Fluorine 18 (18F)-fluciclovine and prostate-specific membrane antigen (PSMA) tracers are commonly used for localizing biochemical recurrence of prostate cancer, but their accuracy in primary tumor detection in the initial staging of high-risk prostate cancer has not been established. Materials and Methods A systematic review was performed of the electronic databases for original studies published between 2012 and 2020. Included studies were those in which 18F-fluciclovine or PSMA PET was used for initial staging of patients with high-risk prostate cancer. The diagnostic performance data were collected for primary tumor with histopathologic results as reference standard. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used for quality appraisal. A random-effects model was used to summarize the effect sizes and to evaluate the difference between two groups. Results Overall, 28 studies met the eligibility criteria, and 17 were included in the meta-analysis (18F-fluciclovine = 4, PSMA = 13). Of these 17 studies, 12 (70%) were judged to have high risk of bias in one of the evaluated domains, and nine studies were deemed to have applicability concerns. The pooled sensitivity, specificity, and diagnostic odds ratio for 18F-fluciclovine versus PSMA were 85% (95% CI: 73%, 92%) versus 84% (95% CI: 77%, 89%) (P = .78), 77% (95% CI: 60%, 88%) versus 83% (95% CI: 76%, 89%) (P = .40), and 18.88 (95% CI: 5.01, 71.20) versus 29.37 (95% CI: 13.35, 64.60) (P = .57), respectively, with no significant difference in diagnostic test accuracy. Conclusion 18F-fluciclovine and PSMA PET demonstrated no statistically significant difference in diagnostic accuracy in primary tumor detection during initial staging of high-risk prostate cancer. Keywords: PET, Prostate, Molecular Imaging-Cancer, Staging Supplemental material is available for this article. © RSNA, 2022.

Defining Diagnostic Criteria for Prostatic Ductal Adenocarcinoma at Multiparametric MRI.

Background Prostatic ductal adenocarcinoma (DAC) is an aggressive histologic variant of prostate cancer that often warrants multimodal therapy and poses a significant diagnostic challenge clinically and at imaging. Purpose To develop multiparametric MRI criteria to define DAC and to assess their diagnostic performance in differentiating DAC from prostatic acinar adenocarcinoma (PAC). Materials and Methods Men with histologically proven DAC who had multiparametric MRI before radical prostatectomy were retrospectively identified from January 2011 through November 2018. MRI features were predefined using a subset of nine DACs and then compared for men with peripheral-zone DACs 1 cm or greater in size and men with matched biopsy-confirmed International Society of Urological Pathology grade group 4-5 PAC, by four independent radiologists blinded to the pathologic diagnosis. Diagnostic performance was determined by consensus read. Patient and tumor characteristics were compared by using the Fisher test, t-tests, and Mann-Whitney U test. Agreement (Cohen κ) and sensitivity analyses were also performed. Results There were 59 men with DAC (median age, 63 years [interquartile range, 56, 67 years]) and 59 men with PAC (median age, 64 years [interquartile range, 59, 69 years]). Predefined MRI features, including intermediate T2 signal, well-defined margin, lobulation, and hypointense rim, were detected in a higher proportion of DACs than PACs (76% [45 of 59] vs 5% [three of 59]; P < .001). On consensus reading, the presence of three or more features demonstrated 76% sensitivity, 94% specificity, 94% positive predictive value [PPV], and 80% negative predictive value [NPV] for all DACs and 100% sensitivity, 95% specificity, 81% PPV, and 100% NPV for pure DACs. The DACs and PACs showed no difference in contrast enhancement (100% vs 100%; P >.99, median T2 signal intensity (254 vs 230; P = .99), or apparent diffusion coefficient (median, 677 10-6 mm2/sec vs 685 10-6 mm2/sec; P = .73). Conclusion The presence of intermediate T2 signal, well-defined margin, lobulation, and/or hypointense rim, together with restricted diffusion and contrast enhancement at multiparametric MRI of the prostate, suggests prostatic ductal adenocarcinoma rather than prostatic acinar adenocarcinoma. © RSNA, 2022 Online supplemental material is available for this article.

Supraclavicular and Axillary Lymphadenopathy Induced by COVID-19 Vaccination on 18F-Fluorthanatrace, 68Ga-DOTATATE, and 18F-Fluciclovine PET/CT.

ABSTRACT: COVID-19 vaccination has started in most countries, and postvaccination imaging is inevitable in the oncologic population. The immune response to the vaccination in the form of reactive lymphadenopathy has been well documented on 18F-FDG PET/CT. We present the imaging findings of 3 patients who have undergone non-FDG PET/CT imaging including 18F-fluorthanatrace, 68Ga-DOTATATE, and 18F-fluciclovine PET/CT. It is crucial to recognize the timing and laterality of immunization to avoid false-positive findings.

Association of High-Intensity Exercise with Renal Medullary Carcinoma in Individuals with Sickle Cell Trait: Clinical Observations and Experimental Animal Studies.

Renal medullary carcinoma (RMC) is a lethal malignancy affecting individuals with sickle hemoglobinopathies. Currently, no modifiable risk factors are known. We aimed to determine whether high-intensity exercise is a risk factor for RMC in individuals with sickle cell trait (SCT). We used multiple approaches to triangulate our conclusion. First, a case-control study was conducted at a single tertiary-care facility. Consecutive patients with RMC were compared to matched controls with similarly advanced genitourinary malignancies in a 1:2 ratio and compared on rates of physical activity and anthropometric measures, including skeletal muscle surface area. Next, we compared the rate of military service among our RMC patients to a similarly aged population of black individuals with SCT in the U.S. Further, we used genetically engineered mouse models of SCT to study the impact of exercise on renal medullary hypoxia. Compared with matched controls, patients with RMC reported higher physical activity and had higher skeletal muscle surface area. A higher proportion of patients with RMC reported military service than expected compared to the similarly-aged population of black individuals with SCT. When exposed to high-intensity exercise, mice with SCT demonstrated significantly higher renal medulla hypoxia compared to wild-type controls. These data suggest high-intensity exercise is the first modifiable risk factor for RMC in individuals with SCT.

Imaging of Neuroendocrine Prostatic Carcinoma.

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer that typically has a high metastatic potential and poor prognosis in comparison to the adenocarcinoma subtype. Although it can arise de novo, NEPC much more commonly occurs as a mechanism of treatment resistance during therapy for conventional prostatic adenocarcinoma, the latter is also termed as castration-resistant prostate cancer (CRPC). The incidence of NEPC increases after hormonal therapy and they represent a challenge, both in the radiological and pathological diagnosis, as well as in the clinical management. This article provides a comprehensive imaging review of prostatic neuroendocrine tumors.

Efficacy and safety of gemcitabine plus doxorubicin in patients with renal medullary carcinoma.

INTRODUCTION: Renal medullary carcinoma (RMC) is a rare and lethal renal cell carcinoma characterized by the loss of tumor suppressor SMARCB1. Molecular profiling studies have suggested that RMC cells may be vulnerable to therapies that generate DNA damage, such as the combination of the nucleoside analog gemcitabine, and topoisomerase inhibitor doxorubicin. PATIENTS AND METHODS: We retrospectively analyzed the records of patients with RMC treated with gemcitabine plus doxorubicin at our institution between January 2005 and September 2020. Best radiographic response and disease progression (RECIST v1.1) were assessed by a blinded radiologist. RESULTS: Sixteen patients were included in the study. All but 1 patient (93.8%) received prior platinum-based chemotherapy. Gemcitabine was given intravenously at 900-1200 mg/m2 and doxorubicin at 40-50 mg/m2 intravenously every 2 weeks. Three patients (18.8%) achieved partial response and 7 (43.8%) patients achieved stable disease. The median progression-free survival was 2.8 months (95% CI, 0-6.0). Median overall survival (OS) from gemcitabine plus doxorubicin initiation was 8.1 months (95% CI, 4.6-11.7) and OS from diagnosis was 15.5 months (95% CI, 4.2-26.8 months). There were no grade ≥ 4 AEs; grade 3 AEs were cytopenias (18.8%), nausea (12.5%), fatigue (12.5%), and cardiotoxicity (6.2%). No somatic alterations were detected in the 9 patients tested by targeted next generation sequencing assays. CONCLUSION: Gemcitabine plus doxorubicin was well tolerated and demonstrated clinical activity in patients with platinum-refractory RMC, with a subset of patients experiencing durable responses lasting longer than 6 months. Further investigation is warranted to determine biomarkers of sensitivity and target mechanisms of resistance.

Durable responses in patients with genitourinary cancers following immune checkpoint therapy rechallenge after moderate-to-severe immune-related adverse events.

BACKGROUND: Immune checkpoint therapy (ICT) prolongs survival in subsets of patients with cancer but can also trigger immune-related adverse events (irAEs) requiring treatment discontinuation. Recent studies have investigated safety of ICT rechallenge after irAEs, and evidence suggests that rechallenge may be associated with improved antitumor responses. However, data are limited on response duration after ICT rechallenge, particularly after severe irAEs. OBJECTIVE: To evaluate safety and efficacy of ICT rechallenge after moderate-to-severe irAEs in patients with renal cell carcinoma (RCC), urothelial carcinoma (UC), and prostate cancer. METHODS: In this retrospective cohort study, medical records from September 25, 2013, to June 1, 2020, for patients with genitourinary (GU) cancers at MD Anderson Cancer Center who were rechallenged with the same or different ICT following irAEs were reviewed. Demographics, ICT exposure, irAEs (grade and treatment), ICT discontinuation or rechallenge, rates of subsequent irAEs (new or recurrent) and antitumor activity (objective response rates and response duration) were reviewed. RESULTS: Sixty-one patients with RCC, UC, and prostate cancer were rechallenged with ICT after experiencing 105 total irAEs. Objective response rates after rechallenge, that is, upgrade in response, were 14% in RCC (4/28), 21% in UC (3/14), and 0% in prostate cancer. All seven patients who achieved upgrade in response had initial grade 2 or 3 irAEs. Responses were durable among these seven patients, with median radiographic progression-free survival not reached (range: 3.7-66.4 months) as of the March 8, 2021, data cut-off (median follow-up 40.9 months (95% CI 35.3 to 46.5)). All achieved complete response except one patient who was lost to follow-up. The rate of subsequent grade 3 or 4 irAEs after rechallenge was 30%, with no fatal irAEs. The rate of recrudescence of the same irAE was 26% (16/61). 54% of patients received corticosteroids (33/61), and 21% received targeted immunosuppression (13/61) for the initial irAEs. CONCLUSIONS AND RELEVANCE: ICT rechallenge after moderate-to-severe irAEs was associated with deep and durable responses in a subset of patients with RCC and UC, with acceptable safety and no fatal events. Strategies to enable ICT resumption after moderate-to-severe irAEs, such targeted immunosuppression, warrant further study.

PET/Computed Tomography in Thyroid Cancer.

Primary thyroid cancers demonstrate distinct biological behaviors depending on their histologic characteristics. The ability to accumulate radioiodine by differentiated thyroid cancer cells is lost in primary aggressive, poorly differentiated and dedifferentiated tumor cells. PET imaging comes into play in these challenging situations where it can provide additive information to radioiodine scintigraphy and conventional imaging. This review focuses on the current guidelines and future prospects of PET imaging in thyroid cancers.