Correlating metabolic and anatomic responses of primary lung cancers to radiotherapy by combined F-18 FDG PET-CT imaging

Outcomes of Modestly Hypofractionated Radiation for Lung Tumors: Pre- and Mid-Treatment Positron Emission Tomography-Computed Tomography Metrics as Prognostic Factors

Many patients with lung tumors have tumors too large for stereotactic ablative radiotherapy and comorbidities precluding concurrent chemotherapy. We report the outcomes of 29 patients treated with hypofractionated radiotherapy (RT) to 60 to 66 Gy in 3-Gy fractions. We also report an exploratory analysis of the prognostic value of the pre- and mid-RT positron emission tomography-computed tomography.

INTRODUCTION

Modestly hypofractionated radiation therapy (HypoRT; 60-66 Gy in 3-Gy fractions) allows patients with locally advanced thoracic tumors and poor performance status to complete treatment within a shorter period without concurrent chemotherapy. We evaluated the outcomes and imaging prognostic factors of HypoRT.

MATERIALS AND METHODS

We retrospectively reviewed the data from all patients with primary and metastatic intrathoracic tumors treated with HypoRT from 2006 to 2012. We analyzed the survival and toxicity outcomes, including overall survival (OS), progression-free survival (PFS), local recurrence (LR), and distant metastasis. We also evaluated the following tumor metrics in an exploratory analysis: gross tumor volume (GTV), maximum standardized uptake value (SUVMax), and metabolic tumor volume using a threshold of ≥ 50% of the SUVMax (MTV50%) or the maximum gradient of fluorine-18 fluorodeoxyglucose uptake (MTVEdge). We assessed the association of these metrics and their changes from before to mid-RT using positron emission tomography-computed tomography (PET-CT) with OS and PFS.

RESULTS

We identified 29 patients, all with pre-RT and 20 with mid-RT PET-CT scans. The median follow-up period was 15 months. The 2-year overall and non-small-cell lung cancer-only rate for OS, PFS, and LR, was 59% and 59%, 52% and 41%, and 27% and 32%, respectively. No grade ≥ 3 toxicities developed. The median decrease in GTV, SUVMax, and MTVEdge was 11%, 24%, and 18%, respectively. Inferior OS was associated with a larger pre-RT MTVEdge (P = .005) and pre-RT MTV50% (P = .007). Inferior PFS was associated with a larger mid-RT SUVMax (P = .003).

CONCLUSION

These findings add to the growing body of data demonstrating promising outcomes and limited toxicity with HypoRT. The pre- and mid-RT PET-CT metrics could be useful for prognostic stratification in future clinical trials.

The clinical impact of the sum of the maximum standardized uptake value on the pretreatment with F-FDG-PET/CT in small-cell lung cancer

OBJECTIVES

The aim of this study was to investigate the clinical significance of the sum of the maximum standardized uptake value (sumSUVmax) on pretreatment positron emission tomography/computed tomography ((18)F-FDG-PET/CT) in newly diagnosed small-cell lung cancer (SCLC).

METHODS

We retrospectively analyzed 145 SCLC patients from March 2005 to June 2013 who underwent pretreatment (18)F-FDG-PET/CT. The sumSUVmax was assessed in all malignant lesions up to a maximum of 5 lesions and a maximum of 2 lesions per organ according to RECIST 1.1.

RESULTS

A significant difference was found between the low and high sumSUVmax groups (low vs. high sumSUVmax, 91.5 vs. 77.3%; p = 0.018) in the response rate (RR) following frontline platinum-based chemotherapy. The group with low sumSUVmax showed significantly better overall survival (OS; p < 0.001) as well as better progression-free survival (PFS; p < 0.001) compared with the group with high sumSUVmax. Moreover, multivariate analysis revealed that a high sumSUVmax alone was an independent poor prognostic factor for OS (hazard ratio 2.676; 95% confidence interval, 1.674-4.277; p < 0.001).

CONCLUSIONS

This study showed that the sumSUVmax adopted from RECIST 1.1 on pretreatment (18)F-FDG PET/CT was significantly correlated with response to treatment, OS, and PFS in patients with SCLC.

The challenges of integrating molecular imaging into the optimization of cancer therapy

We review novel, in vivo and tissue-based imaging technologies that monitor and optimize cancer therapeutics. Recent advances in cancer treatment centre around the development of targeted therapies and personalisation of treatment regimes to individual tumour characteristics. However, clinical outcomes have not improved as expected. Further development of the use of molecular imaging to predict or assess treatment response must address spatial heterogeneity of cancer within the body. A combination of different imaging modalities should be used to relate the effect of the drug to dosing regimen or effective drug concentration at the local site of action. Molecular imaging provides a functional and dynamic read-out of cancer therapeutics, from nanometre to whole body scale. At the whole body scale, an increase in the sensitivity and specificity of the imaging probe is required to localise (micro)metastatic foci and/or residual disease that are currently below the limit of detection. The use of image-guided endoscopic biopsy can produce tumour cells or tissues for nanoscopic analysis in a relatively patient-compliant manner, thereby linking clinical imaging to a more precise assessment of molecular mechanisms. This multimodality imaging approach (in combination with genetics/genomic information) could be used to bridge the gap between our knowledge of mechanisms underlying the processes of metastasis, tumour dormancy and routine clinical practice. Treatment regimes could therefore be individually tailored both at diagnosis and throughout treatment, through monitoring of drug pharmacodynamics providing an early read-out of response or resistance.

Cine MRI enables better therapeutic planning than CT in cases of possible lung cancer chest wall invasion

THE OBJECTIVE

To evaluate the hypothesis that lung cancer treatment planning (whether or not to use induction therapy) can be improved if respiratory dynamic cine magnetic resonance imaging (RD MR) is used.

METHOD

We studied 100 lung cancer patients, 76 men and 21 women, scheduled for thoracotomies between May 1997 and December 2006 wherein it was unclear preoperatively whether chest wall invasion would be found. We evaluated the accuracy of RD MR as compared with the findings at operation and postoperative pathology. The accuracy of RD MRI for evaluating chest wall invasion was compared with the efficacy of CT and MRI within our own group of patients and with data from the studies of other investigators.

RESULTS

Concerning the evaluation of chest wall invasion, conventional computed tomography (CT) had 43.9% specificity, 60.0% sensitivity and 47.1% accuracy, while RD MR had 68.5% specificity, 100.0% sensitivity and 77.0% accuracy. RD MRI was particularly useful in the evaluation of cancers around 5 cm in diameter that were located adjacent to the diaphragm. Postoperative evaluation of superior sulcus tumor cases that had received induction therapy also showed that the RD MR procedure enabled an accurate decision in 87.5% of cases, and there were no false negative cases.

CONCLUSIONS

RD MR is more useful than CT or standard MRI for evaluating thoracic wall invasion. This noninvasive method enhances the reliability of deciding whether induction therapy should be employed.

Imaging and cancer: a review

Multiple biomedical imaging techniques are used in all phases of cancer management. Imaging forms an essential part of cancer clinical protocols and is able to furnish morphological, structural, metabolic and functional information. Integration with other diagnostic tools such as in vitro tissue and fluids analysis assists in clinical decision-making. Hybrid imaging techniques are able to supply complementary information for improved staging and therapy planning. Image guided and targeted minimally invasive therapy has the promise to improve outcome and reduce collateral effects. Early detection of cancer through screening based on imaging is probably the major contributor to a reduction in mortality for certain cancers. Targeted imaging of receptors, gene therapy expression and cancer stem cells are research activities that will translate into clinical use in the next decade. Technological developments will increase imaging speed to match that of physiological processes. Targeted imaging and therapeutic agents will be developed in tandem through close collaboration between academia and biotechnology, information technology and pharmaceutical industries.