Does PET/CT Aid in Detecting Primary Carcinoma in Patients with Skeletal Metastases of Unknown Primary?

BACKGROUND: Patients older than 40 years presenting with osteolytic bone lesions are likely to have a diagnosis of carcinoma, even if they had no prior cancer diagnosis. For patients with no prior cancer diagnosis, there is a well-accepted algorithm to determine a potential primary site. That algorithm, however, leaves approximately 15% of people without a detectable primary tumor site, making treatment decisions extremely difficult. Positron emission tomography (PET) fused with CT, more commonly known as PET/CT, has emerged as an important staging modality for many other malignancies but has been used in a very limited fashion in musculoskeletal oncology. QUESTIONS/PURPOSES: We asked (1) What is the ability of PET/CT to detect the source of the primary tumor in patients with a skeletal metastasis of unknown primary? (2) How does PET/CT perform in detecting metastases in other sites in patients with a skeletal metastasis of unknown primary? METHODS: A retrospective analysis between 2006 and 2016 of the pathology database of a single tertiary center identified 35 patients with a biopsy-proven skeletal metastasis (histologically confirmed carcinoma or adenocarcinoma) and a PET/CT scan that was performed after the standard diagnostic evaluation of the primary cancer site. Patients were identified through use of our pathology database to identify all biopsy-proven bone carcinomas. This was then cross referenced with our imaging database to identify all patients who were at any time evaluated with PET/CT. During this time, we identified 1075 patients with biopsy-proven metastatic bone disease through our pathology database. Any indication for a PET/CT was included, and was most often done for staging of the identified malignancy or evaluation for the unknown source. Data regarding the ability of PET/CT to find or confirm the primary cancer and all metastatic sites were evaluated. The standard diagnostic evaluation (history and physical, laboratory evaluation, CT of the chest/abdomen/pelvis and whole body bone scan) identified the primary cancer in 22 of the 35 patients. Among the 35 patients, there were a total of 176 metastatic sites of disease identified, with 115 identified with the standard diagnostic evaluation (before PET/CT). RESULTS: Among patients with a skeletal metastasis of unknown primary, PET/CT was unable to identify the primary cancer in 12 of 13 patients. PET/CT confirmed the site of the known primary cancer in all 22 patients. There were 176 total metastatic sites. Of the 115 metastases known before PET/CT, PET/CT failed to identify three of 115 (3% false-negative rate). CONCLUSIONS: PET/CT may not provide any additional benefit over the standard evaluation for identification of the primary cancer in patients with a skeletal metastasis of unknown primary, although it may have efficacy as a screening tool equivalent or superior to the standard diagnostic algorithm for evaluation of the overall metastatic burden in these patients. LEVEL OF EVIDENCE: Level III, diagnostic study.

Improving midterm results justify the continued use of bare-metal stents for endovascular therapy for chronic mesenteric ischemia.

OBJECTIVE: The objective of this study was to evaluate the contemporary results of interventions in the celiac axis (CA) and superior mesenteric artery (SMA) for chronic mesenteric ischemia (CMI) and factors associated with patency and symptom-free survival. METHODS: A retrospective review of patients with CMI treated with angioplasty and stenting with bare-metal stents from 2003 to 2014 was conducted. Demographic, history, risk factor, preoperative testing, and technical variables were collected and subject to univariate analysis, with end points of patency loss. The patients were divided into early (2003-2008) and late (2009-2014) groups to compare early and contemporary results. Correlates of patency were then subject to further univariate and multivariable analysis. RESULTS: From 2003 to 2014, there were 150 patients (39 men, 111 women; age, 70.7 ± 11.1 years) with CMI who underwent interventions on the CA (56 vessels) and the SMA (133 vessels); 38 patients had both CA and SMA intervention. Primary patency for the CA was 86% (95% confidence interval [CI], 73-99) at 1 year and 66% (95% CI, 46-87) 3 years; for the SMA, primary patency was 81% (95% CI, 72-89) at 1 year and 69.0% (95% CI, 58-81) at 3 years. Increased age was associated with improved results in the SMA (hazard ratio [HR], 0.96; 95% CI, 0.92-1.00; P = .028). Chronic total occlusion in the SMA conferred worse patency compared with stenosis (HR, 2.38; 95% CI, 1.03-5.47; P = .042), and younger patients (<70 years) had a higher proportion of SMA occlusion (38.9% vs 22.8; P = .045). In the SMA, comparing early (2003-2008; 68 patients) vs late (2009-2014; 65 patients), primary patency was better in the late experience (3 years, 59% vs 77%; P = .016). The late cohort was older (early, 68.1 ± 12.5 years vs 72.5 ± 9.7 years; P = .024). The late cohort had a higher incidence of ostial flaring of the stent (early, 44.1%; late, 72.3%; P < .001). Multivariable analysis revealed only ostial flaring to be associated with improved patency in the SMA (HR, 0.29; 95% CI, 0.12-0.69; P = .006). CONCLUSIONS: Intervention for CMI has acceptable midterm results, and with experience and adoption of newer techniques, the results appear to be improving. Patients older than 70 years have better results than younger patients, and this may reflect a more malignant presentation in the younger patients. Ostial flaring proved to be the single factor on multivariate analysis associated with improved patency and was adopted in the late group. These data support the continued use of bare-metal stents in the treatment of CMI.