by Dr. C.H. Weaver M.D. updated 2/2019
According to an article published in The New England Journal of Medicine, integrated PET-CT imaging improves the accuracy of staging for non-small cell lung cancer (nsclc). Since treatment depends on the stage of the cancer, the accuracy of detection is imperative to determine the most effective type of treatment for the patient without delay.
Treatment options depend on the stage, or extent, of cancer and may consist of surgery, radiation or systemic treatment with chemotherapy or precision cancer medicines. .
Common methods for determining the stage of NSCLC in patients following initial diagnosis include computerized tomography (CT) scans, magnetic resonance imagery (MRI) scans, bone scans and sampling of lymph nodes in the chest. Whole-body positron emission tomography (PET) scans and integrated PET-CT scanners have been developed, which involve computer integration of both types of scans to provide an even more accurate reading.
A PET scan is similar to a CT scan; however, PET scans can detect live cancer tissue. Prior to a PET scan, the patient receives an injection of a substance that contains a type of sugar attached to a radioactive isotope. The cancer cells “take up” the sugar and attached isotope, which emits positively charged, low energy radiation (positrons). The positrons react with electrons in the cancer cells, which create the production of gamma rays. The gamma rays are then detected by the PET machine, which transforms the information into a picture. If no gamma rays are detected in the scanned area, it is unlikely that the mass in question contains living cancer cells.
Researchers from Switzerland have reported that 88% of patients utilizing an integrated PET-CT scan are accurately staged compared to 65% of patients utilizing visual correlation of PET and CT scans, 58% with CT scans alone and 40% with PET scans alone.
Other researchers have confirmed the value of combined PET/CT.
The use of integrated PET/CT resulted in more accurate staging than use of PET alone. Integrated PET/CT produced these results:
- Accurately staged 83% of patients
- Overstaged 10% of patients
- Understaged 7% of patients
In contrast, PET alone had the following, less precise results:
- Accurately 57% of patients
- Overstaged 20% of patients
- Understaged 23% of patients
Researchers conclude that integrated PET-CT significantly improves staging accuracy compared to PET or CT alone or visual correlation of PET and CT. Patients diagnosed with NSCLC may wish to speak with their physician about the risks and benefits of integrated PET-CT.
Another NEJM research report demonstrated that preoperative PET/CT for NSCLC reduces the total number of thoracotomies as well as the number of futile thoracotomies, without affecting survival which can prevent NSCLC patients from undergoing unnecessary surgery.
Non-Invasive Imaging Detects Responders to EGFR Inhibitors in Lung Cancer.
A novel use of positron emission tomography (PET) scans predicts which patients with lung cancer will respond to epidermal growth factor receptor (EGFR) inhibitors, further personalizing cancer care with non-invasive methods. These results were recently presented at the 14th World Conference on Lung Cancer, sponsored by the International Association for the Study of Lung Cancer.
The EGFR pathway is involved in cellular growth and replication. In a significant portion of cancers, the EGFR pathway contains a mutation and does not function normally. Novel medications for cancer, referred to as EGFR inhibitors, reduce or stop unchecked cellular growth through this pathway among patients with EGFR mutations.
Patients with lung cancer often undergo testing to determine whether they have mutations within their EGFR pathways, ultimately establishing whether EGFR inhibitors may be effective treatment. This testing involves invasive methods to remove cancerous tissue which undergoes subsequent laboratory testing.
Researchers from Amsterdam recently conducted a clinical trial to evaluate the accuracy with which PET scans using Tarceva® (erlotinib), an EGFR inhibitor, could predict responses to treatment with the drug. The trial included 10 patients with non-small cell lung cancer (NSCLC) who initially underwent standard laboratory testing for EGFR mutations. Five patients had EGFR mutations and 5 patients did not. The patients then underwent PET scanning with radiolabeled Tarceva.
Patients whose cancer absorbed high levels of the radiolabeled Tarceva during the scan were the only patients who responded to subsequent therapy with Tarceva.
Dr. Idris Bahce, the principle investigator of the study, stated that “This is an important finding, as it indicates that this new imaging PET technique may be a non-invasive predictive marker that identifies NSCLC patients who benefit from treatment with [EGFR inhibitors].” Although this was a small, preliminary study, these results provide a novel approach to a personalized and less invasive method of determining which patients will respond to treatment with EGFR inhibitors. Further studies evaluating this type of procedure are being planned.
- Fischer B, Lassen U, Mortensen J et al. Preoperative staging of lung cancer with combined PET-CT. New England Journal of Medicine. 2009;361:32-9.
- Lardinois D, Weder W, Hany T, et al. Staging of non-small-cell lung cancer with integrated positron-emission tomography and computed tomography. The New England Journal of Medicine. 2003;348:2500-2507.
- Halpern BS, Schiepers C, Weber WA et al. Presurgical Staging of Non-small Cell Lung Cancer. Chest . 2005;128:2289-2297.
- Reference: Bahce I, et al. In vivo selection of non-small cell lung cancer patients with activating mutations in the tumor epidermal growth factor receptor using [11C]erlotinib and positron emission tomography. Presented at the 14th World Conference on Lung Cancer. July 3-7, 2011. Amsterdam, Netherlands. Abstract PRS.5.
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