Download PDF
CC BY-NC-ND 4.0 · World J Nucl Med 2020; 19(01): 47-51
DOI: 10.4103/wjnm.WJNM_93_18
Original Article

Detection efficiency of 18F-flourodeoxyglucose positron emission tomography/computed tomography for primary tumors in patients with carcinoma of unknown primary

Nosheen Fatima
Department of Radiology, Aga Khan University Hospital, Karachi, Pakistan
,
Maseeh Uz Zaman
Department of Radiology, Aga Khan University Hospital, Karachi, Pakistan
,
Areeba Zaman
1   Department of Medicine, Dow Medical College, Ruth Pfau Hospital, Karachi, Pakistan
,
Unaiza Zaman
1   Department of Medicine, Dow Medical College, Ruth Pfau Hospital, Karachi, Pakistan
,
Sidra Zaman
1   Department of Medicine, Dow Medical College, Ruth Pfau Hospital, Karachi, Pakistan
,
Rabia Tahseen
2   Department of Radiation Oncology, Aga Khan University Hospital, Karachi, Pakistan
› Author Affiliations
› Further Information
Also available at
   Permissions and Reprints

Abstract

Carcinoma of unknown primary (CUP) is defined as biopsy proven tumor metastases that remains unidentified after a thorough diagnostic evaluation. The purpose of this study was to find the detection efficiency of 18F-flourodeoxyglucose positron emission tomography/computed tomography (18FDG PET/CT) in patients with CUP. This prospective study was conducted at PET/CT Section of Department of Radiology, Aga Khan University Hospital Karachi, Pakistan from August 2017 to January 2018. Patients with a history of CUP referred for 18FDG PET/CT scan for detection of primary sites during the study were recruited. 18FDG PET/CT scan was acquired using standardized protocol, and patients with suspected primary sites underwent biopsies. Scan findings and biopsy results were analyzed to find the detection rate, sensitivity, area under curve (AUC), and positive predictive value (PPV). As no biopsy was performed in negative scan, true negative, and specificity could not be calculated. During the study, 46 consecutive patients with CUP were included. Mean age of cohort was 58 ± 17 years (63% male and 37% female) having a mean body mass index of 24.70 ± 4.97 kg/m2. Thirty-four patients (34/46) found to have a hypermetabolic focus suggestive of the primary tumor with known metastatic sites and subjected to biopsy which turned out to be positive in 26/34 patients (true positive). The primary tumor was detected in gastrointestinal and hepatobiliary in 8 (17%), head and neck in 6 (13%), genitourinary 4 (09%), lung 3 (06%), and miscellaneous sites in 5 (11%) patients. Detection rate, sensitivity and PPV of 18FDG PET/CT were 57%, 68%, and 76%, respectively. Remaining 12/46 patients with negative 18FDG PET/CT for primary focus did not have biopsy. Receiver operating character curve revealed fair diagnostic strength of 18FDG PET/CT for detecting unknown primary (AUC 0.667; P = 0.054; standard error = 0.083; confidence interval: 0.504–0.830). We conclude that 18FDG PET/CT is an effective tool for detecting primary tumor in patients with CUP and its upfront use could preclude the use of many futile diagnostic procedures. Furthermore, higher resolution scanners and acquiring delayed images in patients with negative study could reduce false-negative results in patients with CUP.

Keywords

18-Flourodeoxyglucose positron emission tomography/computed tomography - carcinoma of unknown primary - detection efficiency

Financial support and sponsorship

Nil.




Publication History

Received: 24 October 2018

Accepted: 20 November 2018

Article published online:
19 April 2022

© 2020. Sociedade Brasileira de Neurocirurgia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India

 

  • References

  • 1 Kim KW, Krajewski KM, Jagannathan JP, Nishino M, Shinagare AB, Hornick JL, et al. Cancer of unknown primary sites: What radiologists need to know and what oncologists want to know. AJR Am J Roentgenol 2013;200:484-92.
  • 2 Fizazi K, Greco FA, Pavlidis N, Pentheroudakis G; ESMO Guidelines Working Group. Cancers of unknown primary site: ESMO clinical practice guidelines for diagnosis, treatment and follow-up. Ann Oncol 2011;22 Suppl 6:vi64-8.
  • 3 Fernandez-Cotarelo MJ, Guerra-Vales JM, Colina F, de la Cruz J. Prognostic factors in cancer of unknown primary site. Tumori 2010;96:111-6.
  • 4 Kwee TC, Basu S, Cheng G, Alavi A. FDG PET/CT in carcinoma of unknown primary. Eur J Nucl Med Mol Imaging 2010;37:635-44.
  • 5 Pavlidis N, Fizazi K. Carcinoma of unknown primary (CUP). Crit Rev Oncol Hematol 2009;69:271-8.
  • 6 Aglund M, Kjems E. Statistics on Cancer of Unknown Primary (in Danish) [The Danish Cancer Society]; 12 January, 2017. Available from: https://www.cancer.dk/hjaelp-viden/kraeftformer/metastaser-spredning/ukendt-primaer-tumor/statistik-ukendt-primaer-tumor/. [Last accessed on 2018 Apr 30].
  • 7 Taylor MB, Bromham NR, Arnold SE. Carcinoma of unknown primary: Key radiological issues from the recent national institute for health and clinical excellence guidelines. Br J Radiol 2012;85:661-71.
  • 8 Boellaard R, Delgado-Bolton R, Oyen WJ, Giammarile F, Tatsch K, Eschner W, et al. FDG PET/CT: EANM procedure guidelines for tumour imaging: Version 2.0. Eur J Nucl Med Mol Imaging 2015;42:328-54.
  • 9 Elboga U, Kervancioǧlu S, Sahin E, Basibuyuk M, Celen YZ, Aktolun C. Utility of F-18 fluorodeoxyglucose posıtron emıssıon tomography/computed ın carcınoma of unknown primary. Int J Clin Exp Pathol 2014;7:8941-6.
  • 10 Rohren EM, Turkington TG, Coleman RE. Clinical applications of PET in oncology. Radiology 2004;231:305-32.
  • 11 Park JS, Yim JJ, Kang WJ, Chung JK, Yoo CG, Kim YW, et al. Detection of primary sites in unknown primary tumors using FDG-PET or FDG-PET/CT. BMC Res Notes 2011;4:56.
  • 12 Roh JL, Kim JS, Lee JH, Cho KJ, Choi SH, Nam SY, et al. Utility of combined (18)F-fluorodeoxyglucose-positron emission tomography and computed tomography in patients with cervical metastases from unknown primary tumors. Oral Oncol 2009;45:218-24.
  • 13 Freudenberg LS, Fischer M, Antoch G, Jentzen W, Gutzeit A, Rosenbaum SJ, et al. Dual modality of 18F-fluorodeoxyglucose-positron emission tomography/computed tomography in patients with cervical carcinoma of unknown primary. Med Princ Pract 2005;14:155-60.
  • 14 Burglin SA, Hess S, Høilund-Carlsen PF, Gerke O. 18F-FDG PET/CT for detection of the primary tumor in adults with extracervical metastases from cancer of unknown primary: A systematic review and meta-analysis. Medicine (Baltimore) 2017;96:e6713.
  • 15 Gladish GW, Choe DH, Marom EM, Sabloff BS, Broemeling LD, Munden RF. Incidental pulmonary emboli in oncology patients: Prevalence, CT evaluation, and natural history. Radiology 2006;240:246-55.
  • 16 Pentheroudakis G, Briasoulis E, Pavlidis N. Cancer of unknown primary site: Missing primary or missing biology? Oncologist 2007;12:418-25.