Visualisation and assessment of the protein synthesis rate of lung cancer using carbon-11 tyrosine and positron emission tomography

Our plain-English summary of Visualisation and assessment of the protein synthesis rate of lung cancer using carbon-11 tyrosine and positron emission tomography, by R. Pieterman, A. Willemsen, M. Appel, et al (European Journal of Nuclear Medicine and Molecular Imaging, 2002).

The study

• Authors: R. Pieterman, A. Willemsen, M. Appel, J. Pruim, G. Koëter, W. Vaalburg, H. Groen
• Journal: European Journal of Nuclear Medicine and Molecular Imaging
• Published: 2002;29(2):243-7
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

This study evaluated the potential role of L-(1-(11)C)-tyrosine positron emission tomography (TYR PET) for visualisation and quantification of protein metabolism in lung cancer. Dynamic TYR PET scans of the thorax were performed in 17 patients with lung cancer. Protein synthesis rate (PSR in micromol/min x l) and standardised uptake value (SUV, corrected for body measurements) of tumour tissue and contralateral normal tissue were calculated before and after chemotherapy or radiotherapy. All tumours [11 non-small cell lung carcinomas (NSCLCs), five small cell lung carcinomas (SCLCs), and one pleural mesothelioma] were visualised as a hot spot. The median PSR in tumour tissue was higher than that in corresponding contralateral normal lung tissue before [1.88 micromol/min x l (range 1.10-3.42) vs 0.40 micromol/min x l (range 0.12-0.86); P=0.003] and after treatment [1.33 micromol/min x l (range 0.45-2.21) vs 0.28 micromol/min x l (range 0.18-0.51); P<0.02]. In contrast to PSR of normal lung tissue, PSR of tumour tissue decreased significantly after therapy (P=0.03). Before therapy, no significant difference in PSR between NSCLCs and SCLCs was observed, but after therapy the PSR differed significantly between the subgroups [1.69 micromol/min x l (range 0.63-2.78) for NSCLC vs 0.67 micromol/min x l (range 0.45-0.92) for SCLC; P=0.03], irrespective of the treatment modality. The median SUV of tumour tissue was higher than that in corresponding contralateral normal lung both before and after therapy. Only a weak correlation between PSR and SUV was found when the latter was corrected for body surface area or lean body mass. Carbon-11 labelled tyrosine appears to be a good tracer for visualising lung cancer. PSR of tumour tissue can be used to quantify reduction in the metabolic rate of the tumour. Future studies need to be performed to determine whether TYR PET will supply additional clinical information with treatment implications in patients with lung cancer.

In plain English

This short communication from Groningen University Hospital, the Netherlands, tested whether PET scans with a carbon-11 tyrosine tracer could show lung tumours and measure their protein synthesis rate. The 17 patients (15 men, 2 women; median age 60) had non-small cell lung cancer (11), small cell lung cancer (5) or pleural mesothelioma (1). The article does not discuss asbestos and gives no separate result for the mesothelioma patient. Eleven received chemotherapy and six radiotherapy. Scans were done before treatment (11 patients), halfway through (10) and after treatment (7). All tumours showed up as hot spots. Before treatment, the median protein synthesis rate was 1.88 micromoles per minute per litre in tumour versus 0.40 in the opposite normal lung (P=0.003). After treatment it was 1.33 versus 0.28 (P=0.018). Tumour rates fell significantly after therapy (P=0.034), while normal lung did not change. After treatment, small cell tumours had lower rates than non-small cell tumours (0.67 versus 1.69, P=0.03). The authors concluded that the tracer appears good for visualising lung cancer, and said further studies are needed.

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: Short communication reporting a clinical imaging study: dynamic carbon-11 tyrosine PET scans of the chest, scheduled before, halfway through and after chemotherapy or radiotherapy
• Who was studied: 17 patients (15 male, 2 female; median age 60, range 39 to 87) at Groningen University Hospital, the Netherlands. Diagnoses: squamous cell carcinoma (5), adenocarcinoma (5), large cell carcinoma (1), pleural mesothelioma (1; first thought to be adenocarcinoma, diagnosis amended after pathology review) and small cell lung cancer (5). Study dates not given.
• Exposure: No asbestos or other occupational exposure is reported. The study concerned imaging with the carbon-11 tyrosine tracer (about 370 MBq given intravenously) in patients treated with chemotherapy (11) or local thoracic radiotherapy of 60 Gy over 6 weeks (6 patients with non-small cell lung cancer).
• Main results:
  • Before therapy, all tumours appeared as hot spots on the scans.
  • Before treatment, the median protein synthesis rate (range) was 1.88 (1.10 to 3.42) micromoles per minute per litre in tumour tissue and 0.40 (0.12 to 0.86) in normal lung tissue (P=0.003).
  • Halfway through treatment, the median rate was 0.81 (0.65 to 4.15) in tumour tissue and 0.25 (0.11 to 0.55) in the opposite non-tumour lung (P=0.005).
  • After treatment, the median rate was 1.33 (0.45 to 2.21) in tumour tissue and 0.28 (0.18 to 0.51) in the opposite non-tumour lung (P=0.018). The tumour rate decreased significantly after therapy (P=0.034), while the normal lung rate was not altered.
  • Before therapy, protein synthesis rates in non-small cell and small cell tumours did not differ (P=0.14). After treatment, the median rate was 1.69 (0.63 to 2.78) for non-small cell and 0.67 (0.45 to 0.92) for small cell tumour tissue (P=0.03).
  • Standardised uptake values (SUVs) of tumour tissue were significantly higher than those of normal tissue before, halfway through and after treatment. Tumour SUVs decreased significantly after therapy (P less than 0.05), while normal lung SUVs did not change significantly.
  • Before treatment, protein synthesis rate and SUV were not significantly correlated. After treatment, the authors found only a weak correlation (body surface area version: r=0.68, P less than 0.02; lean body mass version: r=0.59, P less than 0.05).
• The authors' conclusion: The authors concluded that carbon-11 tyrosine appears to be a good tracer for visualising lung cancer, and that the tumour protein synthesis rate can be used to quantify a fall in the tumour's metabolic rate. They suggested SUV may be sufficient for simple tumour measurement, while protein synthesis rate may be of greater value for monitoring response to treatment. They said future studies are needed to find out whether the scan adds clinical information with treatment implications.
• Limitations the authors state:
  • The study was not designed to monitor changes in protein synthesis rate during therapy.
  • The tyrosine tracer was not compared with the FDG tracer.
  • Values were not normalised for tumour tissue density. The authors noted that the information needed for such a correction is generally unavailable.
  • Measuring protein synthesis rate requires arterial blood sampling, which prolongs the study.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Lung Cancer, PET Scan, Thorax, Chemotherapy, Carcinoma, Pleural Mesothelioma.

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