Lung Cancer

PET/CT , with its ability to combine anatomical and functional information ,is regarded as a standard of care in the management of non-small-cell lung carcinoma (NSCLC). The most common indications for PET/CT in lung cancer are

  1. Morphological and functional characterization of pulmonary nodules less than or equal to 3 cm in diameter Incidental finding of pulmonary nodules on routine imaging and the introduction of lung screening has increased the number of pulmonary nodules identified in the last decade. The availability of treatment option for early-stage lung cancer with SABR (Stereotactic ablative radiotherapy) even in patients who are not fit for either a biopsy or radical treatment with surgery or radiotherapy has marked the need for identifying the nodules with malignant potential from the functional information on PET for early treatment.
  2. Staging of NSCLC: Accurate staging of non-small cell lung cancer is critically important for determining the optimal management of these patients. FDG PET/CT is the single most sensitive and accurate modality to detect hilar and mediastinal nodal involvement and metastatic disease, including local, regional, or distant metastases (except in the brain, where MRI is more sensitive). PET/CT has changed management in NSCLC in 30–40% of cases. Developments in the management of patients with small volume metastases (1-3) with a radical intent has increased the use of PET in this group of patients to confirm oligometastases prior to treatment.
  3. Evaluation of treatment response is vitally important to guide change in the systemic therapy management of lung cancer and identify patients with good response for consolidation with local therapy. PET/CT has been valuable in assessing response to treatment, including systemic therapy (chemotherapy, targeted therapy, and immunotherapy) radiation therapy, or in combination. The improved sensitivity in using metabolic criteria instead of anatomic criteria makes PET/CT an important modality in evaluating treatment response especially where there are anatomic changes such as atelectasis and inflammation in the lungs and post-radiation fibrosis, each of which makes CT interpretation difficult.
  4. Radiotherapy planning PET/CT is critically important in radiation therapy planning. PET/CT can accurately delineate gross tumour volume and functional tumour volume, which are critically important to guide radiotherapy. The degree of uptake by of the tumour of F-18 FDG can predict response to radiotherapy as well as outcome. Higher uptake (increased SUV) suggests decreased survival.
  5. Detection of residual disease after primary treatment- PET is very helpful in identifying residual active disease after completion of a course of systemic therapy to benefit patients with minimal residual disease with consolidation local therapy to maximise local control.
  6. Serial PET/CT studies with F-18 FDG can be useful in detecting recurrent disease. The sensitivity, specificity and accuracy are very high in detecting recurrent disease (around 90%) The level of SUV in these lesions can be predictive of survival, as higher SUV levels indicate a poorer survival rate
  7. PET/CT is increasingly being used in the staging, response assessment and early detection of relapse in small cell lung cancer.