PET scan contribution in chest tumor management: a systematic review for thoracic surgeons

Our plain-English summary of PET scan contribution in chest tumor management: a systematic review for thoracic surgeons, by L. Duranti, F. Leo, U. Pastorino (Tumori, 2012).

The study

• Authors: L. Duranti, F. Leo, U. Pastorino
• Journal: Tumori
• Published: 2012;98(2):175-84
• Type of article: Systematic review
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Aims And Background: In the 90s, the introduction of positron emission tomography (PET) represented a milestone in the staging of thoracic tumors. In the last 10 years, PET scan has been widely adopted in thoracic oncology, showing high accuracy in diagnosis and staging and with promising issues in defining prognosis. The aim of this systematic review was to focus on the results and pitfalls of PET scan use in the modern management of chest tumors.

Methods And Study Design: The literature search was performed on May 2010 in PubMed, Embase, and Cochrane according to PRISMA protocol. The search was restricted to publications in English, using in the same string the word "PET" with 9 different chest tumors; results were then filtered by eliminating technical articles, focusing only on papers in which surgery was considered as a potential diagnostic or therapeutic tool. From 6600 papers initially selected, 99 manuscripts were fully analyzed.

Results: Glucose uptake is a metabolic marker useful in the diagnosis and staging of chest tumors. In lung cancer screening, standard uptake value is helpful in defining the risk of malignancy of isolated pulmonary nodules. The addition of PET scan to conventional staging increases detection of nodal and distant metastases in lung cancer, esophageal cancer and malignant mesothelioma. In thymoma, a close relationship between standard uptake value, histology, and Masaoka stage has been advocated. This link between glucose uptake and prognosis suggests that PET translates biological tumor behavior into clinically detectable findings.

Conclusions: PET scan has a crucial role in thoracic oncology due to its impact on diagnosis, staging and prognosis. PET scan expresses the biological behavior of tumors, opening interesting perspectives in chest tumor management and improving detection and stage grouping in lung cancer. It anticipates the diagnosis in long-incubating diseases such as mesothelioma and increases biological knowledge of rare diseases, such as thymoma and other mediastinal tumors.

In plain English

This article was a systematic review, not a new study of patients. In May 2010 the authors searched PubMed, Embase and Cochrane for English-language papers on PET in nine chest tumor types, including mesothelioma. From 6600 papers first found, they kept 99 in which surgery was considered as a diagnostic or treatment tool. The review did not study asbestos exposure. For malignant pleural mesothelioma, the reviewed studies reported that PET improved detection of lymph node spread and of disease outside the chest. In patients otherwise able to have surgery, PET-positive sites still had to be verified to avoid false positives. Reviewed studies found glucose uptake to be an independent prognostic indicator; the risk of death was reported to rise 5% per one-unit increase in maximum standardized uptake value (SUVmax). In pleural thickening, an uptake cutoff of 2.2 was reported to separate mesothelioma from benign disease, with sensitivity 88%, specificity 93% and accuracy 90%. The authors concluded that PET may anticipate diagnosis in long-incubating diseases such as malignant mesothelioma. They noted this prognostic evidence came from limited series of patients.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: systematic review of published literature (searched according to the PRISMA protocol)
• Who was studied: Published papers, not patients. 6600 papers were found at first and 99 were analyzed in full. The papers covered PET in chest tumors (lung cancer, bronchoalveolar carcinoma, carcinoid, mesothelioma, thymoma, lymphoma, germ cell tumors, neurogenic tumors, chest wall tumors) and were restricted to those in which surgery was considered as a potential diagnostic or therapeutic tool.
• Exposure: No asbestos or fiber exposure was studied. The subject was PET scanning, mainly 18F-FDG PET and PET-CT, used in the diagnosis, staging, prognosis and follow-up of chest tumors.
• Main results:
  • In malignant pleural mesothelioma, the reviewed studies reported that FDG-PET improved both nodal staging and detection of disease outside the chest, avoiding surgical over-treatment.
  • In mesothelioma patients who would otherwise be potentially operable, PET-positive sites still had to be verified to avoid false positives. Some false positives were related to previous diagnostic surgical procedures; the article's example is mediastinal uptake after talc pleurodesis.
  • In malignant pleural mesothelioma, glucose uptake was reported as an independent prognostic indicator. The risk of death was reported to increase by 5% for each unit increase in SUVmax. Table 5 lists this finding under Flores et al., 137 patients.
  • In pleural thickening, an SUV cutoff of 2.2 was reported to discriminate between mesothelioma and benign disease, with sensitivity 88%, specificity 93% and overall accuracy 90% (P less than 0.001). These figures are drawn from several cited studies (references 66 to 69).
  • Table 5 lists one study (Yildirim et al., 31 patients) that compared mesothelioma with asbestos-related pleural disease, with a maximum SUV cutoff of 2.2.
  • The role of PET in follow-up after mesothelioma surgery was described as a matter of debate because of the high number of artifacts. Its contribution was effective only when uptake was elevated (SUV above 10).
  • In one study listed (Tan et al., 44 patients), PET-CT had a sensitivity of 94% and a specificity of 100% in detecting recurrent mesothelioma.
  • In lung cancer, the PLUS multicenter randomized trial reported a 51% reduction in futile thoracotomies when FDG-PET was added to conventional staging.
• The authors' conclusion: The authors concluded that FDG-PET opens interesting perspectives in chest tumor management. In their view, it improves detection and stage grouping in lung cancer and anticipates diagnosis in long-incubating diseases such as malignant mesothelioma.
• Limitations the authors state:
  • The link between glucose uptake and prognosis in thymoma and mesothelioma was suggested only in limited series of patients.
  • Artifacts from previous treatments such as surgery or radiotherapy increase the risk of false-positive PET results.

Topics

Medical terms in this study, explained in our Lexicon: PET Scan, Systematic Review, Staging, Prognosis, Low-Dose CT Screening, Lung Cancer, Esophageal Cancer, Malignant Mesothelioma.

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