[What dose escalation in the treatment of locally advanced non-small cell lung cancer?] / Quelle augmentation de doses dans le traitement des cancers bronchiques non à petites cellules localement avancés ?

Despite significant therapeutic advances in the treatment of locally advanced inoperable non-small cell lung cancer (NSCLC), notably through adjuvant immunotherapy, the rate of therapeutic failure remains high. The use of positron emission tomography with fluorodeoxyglucose (FDG-PET), respiratory motion and intensity modulated radiotherapy (IMRT) have led to therapeutic improvements with reduced toxicity and better local control. The optimal dose to be delivered remains unknown due to discordant results of studies for almost 20 years and the way to define the area to benefit from a dose increase (whole volume, subvolume defined by pre- or per-radiotherapy PET).

Comparison of Hypermetabolic and Hypoxic Volumes Delineated on [18F]FDG and [18F]Fluoromisonidazole PET/CT in Non-small-cell Lung Cancer Patients.

PURPOSE: The high rates of failure in the radiotherapy target volume suggest that patients with stage II or III non-small-cell lung cancer (NSCLC) should receive an increased total dose of radiotherapy. 2-Deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and [18F]fluoromisonidazole ([18F]FMISO) (hypoxia) uptake on pre-radiotherapy positron emission tomography (PET)/X-ray computed tomography (CT) have been independently reported to identify intratumor subvolumes at higher risk of relapse after radiotherapy. We have compared the [18F]FDG and [18F]FMISO volumes defined by PET/CT in NSCLC patients included in a prospective study. PROCEDURES: Thirty-four patients with non-resectable lung cancer underwent [18F]FDG and [18F]FMISO PET/CT before (pre-RT) and during radiotherapy (around 42 Gy, per-RT). The criteria were to delineate 40 % and 90 % SUVmax thresholds on [18F]FDG PET/CT (metabolic volumes), and SUV > 1.4 on pre-RT [18F]FMISO PET/CT (hypoxic volume). The functional volumes were delineated within the tumor volume as defined on co-registered CTs. RESULTS: The mean pre-RT and per-RT [18F]FDG volumes were not statistically different (30.4 cc vs 22.2; P = 0.12). The mean pre-RT SUVmax [18F]FDG was higher than per-RT SUVmax (12.7 vs 6.5; P < 0.0001). The mean [18F]FMISO SUVmax and volumes were 2.7 and 1.37 cc, respectively. Volume-based analysis showed good overlap between [18F]FDG and [18F]FMISO for all methods of segmentation but a poor correlation for Jaccard or Dice Indices (DI). The DI maximum was 0.45 for a threshold at 40 or 50 %. CONCLUSION: The correlation between [18F]FDG and [18F]FMISO uptake is low in NSCLC, making it possible to envisage different management strategies as the studies in progress show.

How to work together between nuclear medicine and radiotherapy departments?

Among the available imaging techniques, functional imaging provided by nuclear medicine departments represents a tool of choice for the oncoradiotherapist for targeting tumour activity, with positron emission tomography as the main modality. Before, during or after radiotherapy, functional imaging helps guide the oncoradiotherapist in making decisions and in the strategic choice of pathology management. Setting up a working group to ensure perfect coordination at all levels is the first step. Key points for a common and coordinated management between the two departments are the definition of an organizational logistic, training of personnel at every levels, standardization of nomenclatures, the choice of adapted and common equipment, implementation of regulatory controls, and research/clinical routine continuum. The availability of functional examinations dedicated to radiotherapy in clinical routine is possible and requires a convergence of teams and a pooling of tools and techniques.

["Definition of target volume: When et how can the radiation oncologist use PET?"] / « Définition des volumes cibles : quand et comment l'oncologue radiothérapeute peut-il utiliser la TEP ? ¼.

PET/CT has become a standard examination in oncology but is probably still underused for radiotherapy planning. However, except for the clinical research data that shows the interest of this examination in considering personalized and adaptive radiotherapy, it is also important in defining target volumes. However, before using it in clinical practice, a few prerequisites are required to know the acquisition and segmentation methods. Ideally, PET/CT should become a standard examination for radiotherapy departments in the same way as planning CT and tomorrow as MRI.