PET/CT incidental detection of second tumor in patients investigated for pancreatic neoplasms

Definitions of Incidental [18F]FDG PET/CT Findings in the Literature: A Systematic Review and Definition Proposal

Objectives: The objectives of this study were (1) to systematically review the currently used definitions of incidental 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography findings (IPFs) in the literature and (2) to propose an IPF definition. Methods: A systematic search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The search was guided by the question "How is IPF defined?" and was performed in MEDLINE, Embase, and the Cochrane Library. The retrieved studies were reviewed and analyzed. The definitions of IPFs in the included studies were compiled into two sets of categories based on the description of FDG uptake and the specification of clinical factors in defining IPFs. Results: The systematic literature search identified 4852 publications accessible for title-abstract screening, which yielded 395 studies for full-text assessment. Sixty-five studies met the eligibility criteria and were included. Sixty-two percent mentioned "FDG uptake" in their definition. In 40% of the definitions, "Focal FDG uptake" was specified, while "FDG uptake in the surrounding tissue" was included in 15%. Fifty-seven percent stated that IPFs were "Unrelated to PET/CT indication". Thirty-four percent specified IPFs as "Present in other organ than PET/CT indication", whereas 20% included "No known disease related to IPF". Seventeen percent of the definitions comprised a "New finding", while 15% and 11% encompassed a "Clinical asymptomatic patient" and "Not a metastasis", respectively. Finally, 5% of the definitions included "Potential clinical significance". Conclusions: No generally accepted definition of IPFs currently exists. We propose an IPF definition based on explicit FDG uptake and clinical patient-related factors.

Returning Incidental Research Findings From 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography to Participants: A Survey of Investigators From a Clinical Trial of Rheumatoid Arthritis

OBJECTIVE

There are limited data on researchers' attitudes and beliefs on returning and managing incidental research findings from whole body 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG PET/CT) imaging.

METHODS

Site principal investigators (PIs) who enrolled participants for the Treatments Against Rheumatoid Arthritis and Effect on FDG PET/CT (TARGET) trial were surveyed.

RESULTS

Of the 28 TARGET site PIs eligible for the study, 18 consented to participate (response rate: 64%). Many site PIs returned incidental findings to participants (61%), and the most common finding that was returned was serious (but not life-threatening) and treatable (54.5%). More than half of the investigators believed that adequacy of clinical follow up (58.8%) and legal liability if incidental findings are not disclosed (55.6%) were extremely important factors in returning incidental research findings from whole body FDG PET/CT. All investigators felt very obligated to return incidental research findings if scans revealed a treatable, high-risk medical condition. Most investigators felt very obligated to disclose incidental findings with important health implications (94.4%), for which proven preventive or therapeutic interventions exist (77.8%), that provide early detection of a health problem (72.2%), if participants ask for their incidental findings (72.2%), and if scans have established validity for a particular medical condition (61.1%).

CONCLUSION

Although it is recommended that researchers report and manage incidental research findings, our data show differing views and uncertainties on what and how to return, and the extent of follow up needed to manage, incidental findings from whole body FDG PET/CT; this highlights the need for more specific and standardized guidance.

Impact of routine preoperative 18 FDG PET/CT on the surgical management of primary colorectal cancer

OBJECTIVES

Determine the usefulness of [18F]-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸ FDG-PET/CT) in the preoperative setting of colorectal cancer (CRC), assessing its impact on changes in management strategy.

METHODS

Retrospective study of CRC patients who underwent preoperative ¹⁸ FDG-PET/CT and CT staging scans in a single referral center. The agreement between ¹⁸ FDG-PET/CT, contrast-enhanced CT, and colonoscopy for the surgical location was compared using the κ coefficient. Maximum standardized uptake (SUV_max ) value was obtained. Univariate and multivariate analyses were conducted.

RESULTS

One hundred ninety-five patients were included. ¹⁸ FDG-PET/CT improved tumor localization in 84.6% (165/195) of cases (κ value 0.798, p < 0.001), thus correcting endoscopic errors 69.7% (30/43) of the time. In patients with incomplete colonoscopies, ¹⁸ FDG-PET/CT detected synchronous tumors in 2.5% (5/195) patients, overlooked by CT staging scans. Based on extracolonic ¹⁸ FDG-uptake, the second primary malignancy was diagnosed in 7(3.6%,7/195) patients and total accuracy for lymph node and distant metastasis was 66.1% and 98.4%, respectively. The treatment plan was altered in 30 (15.4%, 30/196) patients. There was a significant association between the SUV_max and tumor size (odds ratio [OR] 4.254, p = 0.003) and the depth of tumor invasion (OR 1.696, p = 0.026).

CONCLUSIONS

Based on its ability to aid in preoperative evaluation and definitively alter surgical treatment planning, ¹⁸ FDG-PET/CT should be further evaluated in primary CRC.

F-FDG18PET/CT incidental detection of tumor-to-tumor metastasis in patients investigated for squamous cell lung cancer

Tumor-to-tumor metastasis (TTM) is a well-known entity, although this is still an extremely rare phenomenon. The lung cancers are considered the most frequent metastatic donors while kidney cancers are the most common recipient. The finding of TTM is often incidental during a biopsy of metastases or on surgical specimens but never suspected on radiological assessment of tumor extension. The finding of an unexpected region of Fluorodeoxyglucose (FDG) uptake can occur when performing whole body Positron Emission Tomography/computed tomography (PET/CT) scan and potentially raises the possibility of a second primary tumor. However, PET/CT scan incidental detection of tumor-to-tumor metastasis has never been reported in English literature. We report here a case of clear cell renal carcinoma, receptor of metastases originating from an oligometastatic squamous cell lung cancer detected on the PET/CT scan performed as part of the extension workup. Morphological and immunohistochemical analysis of a percutaneous biopsy of the renal mass were consistent with the diagnosis of a metastasis of lung cancer into renal cell carcinoma. This is the first case of oligometastatic lung cancer with the occurrence of TTM suspected in PET/CT scan. Although this is a rare setting, it should be considered in daily practice, as it could potentially modify the oncological management offered to the patients.

What is the clinical impact of staging and surveillance PET-CT scan findings in patients with bone and soft tissue sarcoma?

BACKGROUND AND OBJECTIVES

Positron emission tomography-computerized tomography (PET-CTs) are becoming increasingly utilized in sarcoma care, workup, and surveillance. This study aimed to describe additional PET-CT findings as well as subsequent workups and changes in the clinical course due to those results.

METHODS

Patient records were retrospectively reviewed, and the additional workups and evaluations triggered by PET-CT findings were qualitatively analyzed to document their results. Additional changes in the clinical course were documented.

RESULTS

A total of 183 bone and soft tissue sarcoma patients underwent PET-CT as part of staging or surveillance. Additional workup was performed in 31.5% (n = 41 of 130) patients who had positive PET-CT findings. Among these, 36.6% (n = 15 of 41) patients had clinically significant findings that altered the clinical course. Overall, 14.8% (n = 27 of 183) experienced a change in the clinical course due to PET-CT.

CONCLUSION

PET-CT often highlights lesions of potential clinical importance. Additional workup, as well as changes in the clinical course, were not infrequent. Future, multi-institutional studies should address the value of PET-CT in sarcoma care.

The clinical application of 18F-FDG PET/CT in pancreatic cancer: a narrative review

Pancreatic cancer is one of the worst prognoses of all malignant tumors, with an annual incidence near its annual mortality rate. To improve the prognosis of patients with pancreatic cancer, it is essential to diagnose and evaluate pancreatic cancer early. Imaging examinations play an essential role in tumor detection, staging, and surgical resection assessment and can provide reliable evidence for the diagnosis and treatment of pancreatic cancer. Currently, imaging techniques commonly used for pancreatic cancer include endoscopic ultrasound (EUS), conventional ultrasound, magnetic resonance imaging (MRI), multidetector spiral computed tomography (MDCT), positron emission tomography/computed tomography (PET/CT), and others PET/CT is a new imaging device composed of PET and CT. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) is a commonly used tracer in the clinic. Cancer cells are more robust than other ordinary cells in that they can ingest glucose, and the structure of glucose is similar to the structure of ¹⁸F-FDG. Therefore, after the injection of ¹⁸F-FDG, ¹⁸F-FDG in tumor cells appears very thick during PET scanning. Therefore, PET/CT can determine the metabolic capacity and anatomical position of pancreatic tumor cells in the body accurately diagnose the patient's condition and tumor location. It plays a vital role in early diagnosis and accurate staging, predicts survival, and monitors therapeutic effectiveness and pancreatic cancer recurrence. Although ¹⁸F-FDG PET/CT has limitations in identifying inflammatory diseases and tumors, it still has good development potential. This article reviews the clinical application of ¹⁸F-FDG PET/CT in pancreatic cancer.

The Role of Positron Emission Tomography in Pancreatic Cancer and Gallbladder Cancer

18F-FDG-PET is complementary to conventional imaging in patients with clinical suspicion for exocrine pancreatic malignancies. It has similar if not superior sensitivity and specificity for detection of cancer, and when combined with contrast enhanced anatomic imaging of the abdomen, can improve diagnostic accuracy and aid in staging, assessment for resectability, radiation therapy planning, and prognostication. Various metabolic pathways affect FDG uptake in pancreatic ductal adenocarcinoma. The degree of uptake reflects histopathology, aggressiveness, metastatic potential, and metabolic profile of malignant cell and their interaction with cancer stroma. After treatment, FDG-PET is useful for detection of residual or recurrent cancer and can be used to assess and monitor response to therapy in unresectable or metastatic disease. The degree and pattern of uptake combined with other imaging features are useful in characterization of incidental pancreatic lesions and benign processes such as inflammation. Several novel PET radiopharmaceuticals have been developed to improve detection and management of pancreatic cancer. Gallbladder carcinoma is typically FDG avid and when anatomic imaging is equivocal PET can be used to assess metastatic involvement with high specificity and inform subsequent management.

Incidentalomas of the prostate detected by 18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography

INTRODUCTION

Prostate incidentalomas are prostatic lesions suspicious for cancer discovered by imaging patients without a known history of prostatic cancer (PCa) for other reasons. 18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG PET) is used to diagnose, stage, and assess response to treatment for numerous cancers, but it is not routinely used for PCa. We aimed to determine the rate of detection of prostate incidentalomas in patients undergoing FDG PET and to evaluate the natural history of these lesions.

METHODS

A retrospective review was conducted of all FDG PET scans performed between 2005 and 2017 at a single institution. Patients were selected who had prostatic uptake without a history of PCa. Clinical data were collected from electronic medical records to determine how the prostate incidentalomas were further evaluated and to define the rate of malignancy.

RESULTS

A prostate incidentaloma was identified in 309 (1.0%) of 31 019 FDG PET scans performed on men. A prostate-specific antigen (PSA) test was obtained in 40.1% of patients within six months of prostate incidentaloma detection. Six patients underwent a multiparametric magnetic resonance imaging (mpMRI) of the prostate, which identified PCa in one case. Overall, PCa was diagnosed in 33 cases, representing 10.7% of the prostate incidentalomas and 0.1% of the scanned patients. PCa was intermediate- or high-risk in 27 (8.7%) of the prostate incidentalomas.

CONCLUSIONS

Incidental lesions detected in the prostate by FDG PET may represent clinically significant PCa. Referral to a urologist for further evaluation should be considered if the patient is otherwise in reasonable health.

Quadruple Multiple Primary Malignancies: Early Detection of Second Primary Malignancy by Esophagogastroduodenoscopy/Colonoscopy Is Crucial for Patients with Classic Kaposi's Sarcoma

Currently, Kaposi's sarcoma (KS) is treated following the recommendations of international guidelines. These guidelines recommend esophagogastroduodenoscopy/colonoscopy for detecting multicentric KS of visceral lesions. Second primary malignancies (SPMs) are also a common KS complication; however, information on their detection and treatment is unfortunately not yet indicated in these guidelines. This paper reports on an 86-year-old man who suffered from quadruple primary malignancies: skin classic KS with colon adenocarcinoma, oral squamous cell carcinoma (maxilla), and well-differentiated stomach adenocarcinoma. Gastric cancer was incidentally detected during esophagogastroduodenoscopy, which was performed to detect visceral KS. We suggest that esophagogastroduodenoscopy/colonoscopy be routinely performed during the follow-up of patients with KS. As SPMs are crucial complications in patients with KS, these malignancies should be detected as early as possible.

Influence of Smoking and Histologic Subtype on Developing Extrathymic Malignancy in Thymoma Patients

BACKGROUND

Patients with thymomas are at high risk of developing extrathymic malignancies. We investigated the impact of extrathymic malignancies on the prognosis of patients with thymoma who underwent surgery and the risk factors for postoperative extrathymic malignancies.

METHODS

A multicenter retrospective review of 252 patients who underwent surgical resection of thymomas from January 1977 to March 2016 was conducted. The exclusion criteria were recurrent thymoma, rare types of thymoma, and missing data. The overall number and incidence of extrathymic malignancies were calculated. Potential predictors of extrathymic malignancies were also evaluated.

RESULTS

Two hundred twenty-eight patients were analyzed. Fifty-five extrathymic malignancies were observed (23 postoperative, 8 synchronous, and 24 preoperative). Among the overall cohort, the incidence of extrathymic malignancies significantly increased the patients' risk of death (hazard ratio [HR], 4.02; 95% confidence interval [CI], 1.72 to 9.40; p < 0.01). Among patients aged less than 70 years, the incidence of extrathymic malignancies was an independent risk factor for death. The incidence of postoperative extrathymic malignancies was significantly higher in patients with indolent forms of thymoma (type A/AB/B1) than aggressive forms (type B2/B3) (p = 0.02). In the multivariate analysis, indolent forms of thymoma (type A/AB/B1) (HR, 4.03; 95% CI, 1.12 to 14.6, p = 0.03) and a history of ever having smoked (HR, 5.29; 95% CI, 1.30 to 21.6; p = 0.02) were significant risk factors for the cumulative incidence of postoperative extrathymic malignancies.

CONCLUSIONS

Extrathymic malignancies increased the risk of death in patients with thymomas. Indolent forms of thymoma and a history of ever having smoked were risk factors for postoperative extrathymic malignancies.