|Positron emission testing for six cancers (brain, cervical, small cell lung, ovarian, pancreatic and testicular): testicular cancer
|Matchar D B, Kulasingam S L, Havrilesky L, Mann L O, Myers E R, McCrory D C, Patwardhan M, Prosnitz R
This review investigated the diagnostic accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) for testicular cancer. Given the poor-quality studies available, the authors appropriately state that it is difficult to draw firm conclusions about the use of FDG-PET in characterising residual disease. However, it may be overoptimistic to conclude that FDG-PET is superior to computed tomography for the initial staging of patients.
To investigate the diagnostic accuracy of fluorodeoxyglucose positron emission tomography (FDG-PET) compared with conventional imaging modalities or histology for initial staging and for the evaluation of residual or recurrent disease in patients with testicular cancer.
MEDLINE was searched up to April 2003 for studies published in the English language; the search terms were reported. In addition, the bibliographies of review articles were screened and some experts were contacted (information obtained from communication with the authors).
Study designs of evaluations included in the review
Studies of at least 12 participants were eligible for inclusion.
Specific interventions included in the review
Studies evaluating the performance of FDG-PET for initial staging and evaluation of residual or suspected recurrent disease were eligible for inclusion. The included studies used computed tomography (CT) magnetic resonance imaging and tumour markers as a comparator, or had no comparator.
Reference standard test against which the new test was compared
Studies were required to use a reference standard for the detection of malignancy to be included in the review, though the standard itself was not specified. The included studies used histology or clinical follow-up of patients as the reference standard.
Participants included in the review
Studies of patients with an established diagnosis of pure seminomas or non-seminomatous germ cell tumours were included.
Outcomes assessed in the review
Inclusion criteria for the outcomes were not specified. The outcome measures used in the review were sensitivity and specificity and impact on therapeutic choice.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.
Assessment of study quality
The following criteria were assessed: whether the sample was representative; clear description of the setting and patient selection; minimisation of differences between patients who received the tests; description of the scanner model; use of clearly defined criteria for test interpretation; use of histopathological or clinical criteria for the confirmation of disease; and blinding of the test reader and person interpreting the reference standard. One point was given for the presence of each criterion and these were summed to give a total quality score.
At least two reviewers assessed the quality of each study and any discrepancies were resolved by consensus.
The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction.
The sensitivity, specificity and associated 95% confidence intervals were calculated where possible.
Methods of synthesis
How were the studies combined?
The studies were described individually and a summary provided.
How were differences between studies investigated?
The studies were grouped based on the review sub-question addressed, and then by quality score.
Results of the review
Twelve studies (n=403) were included: three were prospective, two were retrospective, and in seven the design was unclear.
Out of a maximum possible quality score of 7 points, one study scored 7, eight scored 6, two scored 5 and one scored 4.
Five studies were included that addressed the question of the performance of FDG-PET compared with conventional imaging in initial staging in participants with germ cell tumours. Four studies reported improved sensitivity and specificity for FDG-PET compared with CT. One study found no difference in the sensitivity and specificity of PET and CT.
Eight studies were included that addressed the question of the performance of FDG-PET compared with conventional imaging in characterising post chemotherapy masses as viable tumour or necrosis. Two of the studies did not compare FDG-PET with conventional methods. The estimates of sensitivity varied widely: four studies reported high sensitivity (75 to 100%) and four reported fairly low sensitivity (16 to 67%). The sensitivity of CT ranged from 55 to 100% and was highly dependent on the positivity criterion used, which was not explicitly stated in some studies. In seven studies the specificity of FDG-PET (78 to 100%) was higher than for CT (0 to 86%). One study was included that reported a sensitivity of 73% and a specificity of 88% for FDG-PET in diagnosing recurrent germ cell tumour in patients with rising tumour markers but a normal CT. The same study found 57% of patients had a change in management based on FDG-PET findings compared with CT alone.
There is direct and fairly consistent evidence that the sensitivity and specificity of FDG-PET is higher than that of CT for the initial staging of patients with germ cell tumours. However, it is difficult to draw firm conclusions about the use of FDG-PET in characterising residual post chemotherapy masses due to methodological weaknesses in the studies.
The review addressed a clearly stated research question, though the inclusion criteria were very broad. The limited searches, combined with the restriction to English language publications, might have resulted in the loss of relevant data. The review methodology was poorly described and, apart from an assessment of study quality, it was unclear whether appropriate measures were taken to reduce error and bias. The methodological quality of the studies was assessed and reported, though it did not appear to be a very sensitive tool as a study received a near perfect score despite lack of clarity on whether it was prospective, whether enrolment was consecutive, and the lack of blinding of the gold standard reader. The studies were summarised, rather than synthesised, making it difficult to get a clear overview of the findings. The authors' conclusions about the use of FDG-PET post chemotherapy were appropriately cautious given the limitations of the data available. However, the conclusions about initial staging could have been more cautious given the limitations of the studies and small study sizes.
Implications of the review for practice and research
The authors did not state any implications for practice or further research.
Agency for Healthcare Research and Quality, contract number 290-02-0025.
Matchar D B, Kulasingam S L, Havrilesky L, Mann L O, Myers E R, McCrory D C, Patwardhan M, Prosnitz R. Positron emission testing for six cancers (brain, cervical, small cell lung, ovarian, pancreatic and testicular): testicular cancer Rockville, MD, USA: Agency for Healthcare Research and Quality. Technology Assessment. 2004
Subject indexing assigned by CRD
Male; Testicular Neoplasms; Tomography, Emission-Computed; Tomography, X-Ray Computed
Date bibliographic record published
Date abstract record published
This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.