Imaging of Novel Oncologic Treatments in Lung Cancer Part 1: Systemic Therapies

Pearls and Pitfalls in the Imaging of Targeted Therapy and Immunotherapy in Lung Cancer

Most lung cancers are diagnosed at advanced stage when the cancer has metastasized outside the lung. These patients are not eligible for curative surgery or radiation therapy and treated with systemic therapy. Advances in the understanding of the biology of lung cancer has resulted in the development of targeted therapy aimed at specific genetic mutations identified with non-small cell lung cancer and immunotherapy that helps the immune system recognize tumors as foreign, stimulates the immune system, and removes the inhibition that allows growth and spread of cancer cells. Tumors treated with targeted or immunotherapies respond differently when compared with traditional chemotherapy and not captured by conventional response criteria such as the World Health Organization criteria and Response Evaluation Criteria in Solid Tumors. Therefore, several modified criteria have been developed to appropriately address the treatment response when using these novel agents. Numerous treatment-related side effects have been described that are important to recognize to avoid misinterpretation as worsening tumor and to ensure appropriate management.

Prospective Evaluation of the First Integrated Positron Emission Tomography/Dual-Energy Computed Tomography System in Patients With Lung Cancer

PURPOSE

The aim of this pilot study was to prospectively evaluate the first integrated positron emission tomography (PET)/dual-energy computed tomography (DECT) system performance in patients with non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

In this single-center, prospective trial, consecutive patients with NSCLC referred for a PET study between May 2017 and June 2018 were enrolled. All patients received contrast-enhanced imaging on a clinical PET/DECT system. Data analysis included PET-based standard uptake values (SUVmax) and DECT-based iodine densities of tumor masses, lymph nodes, and distant metastases. Results were analyzed using correlation tests and receiver operating characteristics curves.

RESULTS

The study population was composed of 21 patients (median age 62 y, 14 male patients). A moderate positive correlation was found between iodine density values (2.2 mg/mL) and SUVmax (10.5) in tumor masses (ρ=0.53, P<0.01). Iodine density values (2.3 mg/mL) and SUVmax (5.4) of lymph node metastases showed a weak positive correlation (ρ=0.23, P=0.14). In addition, iodine quantification analysis provided no added value in differentiating between pathologic and nonpathologic lymph nodes with an area under the curve (AUC) of 0.55 using PET-based SUVmax as the reference standard. A weak positive correlation was observed between iodine density (2.2 mg/mL) and SUVmax in distant metastases (14.9, ρ=0.23, P=0.52).

CONCLUSIONS

The application of an integrated PET/DECT system in lung cancer might provide additional insights in the assessment of tumor masses. However, the added value of iodine density quantification for the evaluation of lymph nodes and distant metastases seems limited.

Post-chemotherapy and targeted therapy imaging of the chest in lung cancer

Non-small-cell lung cancer (NSCLC) is frequently diagnosed when it is not amenable to local therapies; therefore, systemic agents are the mainstay of therapy for many patients. In recent years, treatment of advanced NSCLC has evolved from a general approach primarily involving chemotherapy to a more personalised strategy in which biomarkers such as the presence of genomic tumour aberrations and the expression of immune proteins such as programmed death-ligand 1 (PD-L1), in combination with other elements of clinical information such as histology and clinical stage, guide management. For instance, pathways resulting in uncontrolled growth and proliferation of tumour cells due to epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) rearrangements may be targeted by tyrosine kinase inhibitors (TKIs). In this article, we review the current state of medical oncology, imaging characteristics of mutations, pitfalls in response assessments and the imaging of complications.