CT tumor volume measurement in advanced non-small-cell lung cancer: Performance characteristics of an emerging clinical tool

Response Assessment of Primary Liver Tumors to Novel Therapies: an Imaging Perspective

The latest developments in cancer immunotherapy, namely the introduction of immune checkpoint inhibitors, have led to a fundamental change in advanced cancer treatments. Imaging is crucial to identify tumor response accurately and delineate prognosis in immunotherapy-treated patients. Simultaneously, advances in image acquisition techniques, notably functional and molecular imaging, have facilitated more accurate pretreatment evaluation, assessment of response to therapy, and monitoring for tumor recurrence. Traditional approaches to assessing tumor progression, such as RECIST, rely on changes in tumor size, while new strategies for evaluating tumor response to therapy, such as the mRECIST and the EASL, rely on tumor enhancement. Moreover, the assessment of tumor volume, enhancement, cellularity, and perfusion are some novel techniques that have been investigated. Validation of these novel approaches should rely on comparing their results with those of standard evaluation methods (EASL, mRECIST) while considering the ultimate outcome, which is patient survival. More recently, immunotherapy has been used in the management of primary liver tumors. However, little is known about its efficacy. This article reviews imaging modalities and techniques for assessing tumor response and survival in immunotherapy-treated patients with primary hepatic malignancies.

Prediction Model for Tumor Volume Nadir in EGFR -mutant NSCLC Patients Treated With EGFR Tyrosine Kinase Inhibitors

PURPOSE

In patients with advanced non-small cell lung cancer (NSCLC) and oncogenic driver mutations treated with effective targeted therapy, a characteristic pattern of tumor volume dynamics with an initial regression, nadir, and subsequent regrowth is observed on serial computed tomography (CT) scans. We developed and validated a linear model to predict the tumor volume nadir in EGFR -mutant advanced NSCLC patients treated with EGFR tyrosine kinase inhibitors (TKI).

MATERIALS AND METHODS

Patients with EGFR -mutant advanced NSCLC treated with EGFR-TKI as their first EGFR-directed therapy were studied for CT tumor volume kinetics during therapy, using a previously validated CT tumor measurement technique. A linear regression model was built to predict tumor volume nadir in a training cohort of 34 patients, and then was validated in an independent cohort of 84 patients.

RESULTS

The linear model for tumor nadir prediction was obtained in the training cohort of 34 patients, which utilizes the baseline tumor volume before initiating therapy (V 0 ) to predict the volume decrease (mm 3 ) when the nadir volume (V p ) was reached: V 0 -V p =0.717×V 0 -1347 ( P =2×10 -16 ; R2 =0.916). The model was tested in the validation cohort, resulting in the R2 value of 0.953, indicating that the prediction model generalizes well to another cohort of EGFR -mutant patients treated with EGFR-TKI. Clinical variables were not significant predictors of tumor volume nadir.

CONCLUSION

The linear model was built to predict the tumor volume nadir in EGFR -mutant advanced NSCLC patients treated with EGFR-TKIs, which provide an important metrics in treatment monitoring and therapeutic decisions at nadir such as additional local abrasive therapy.

Tumor Volume Nadir in Patients With ALK-Rearranged Non-Small-Cell Lung Cancer Treated With Alectinib

PURPOSE

Patients with oncogene-driven advanced non-small-cell lung cancer (NSCLC) treated with effective targeted therapy demonstrate characteristic tumor volume dynamics with initial response, nadir, and subsequent regrowth. This study investigated tumor volume nadir and time to nadir in patients with ALK-rearranged advanced NSCLC treated with alectinib.

MATERIALS AND METHODS

In patients with advanced ALK-rearranged NSCLC treated with alectinib monotherapy, tumor volume dynamics were evaluated on serial computed tomography (CT) scans using a previously validated CT tumor measurement technique. A linear regression model was built to predict tumor volume nadir. Time-to-event analyses were performed to evaluate time to nadir.

RESULTS

Among 45 patients who experienced initial volume decrease, 37 patients (25 with tumor regrowth and 12 without regrowth but >6 months follow-up) were studied for nadir volume (V_p). The linear model to predict tumor volume nadir was built using the baseline tumor volume (V₀): V₀-V_p = .696 × V₀ + 5,326 (P < 2 × 10^-16; adjusted R² = 0.86). The percent volume changes at nadir (median, -90.9%, mean, -85.3%) showed larger decrease in patients who were treated with alectinib as first-line therapy than in the ≥2nd-line group and were independent of V₀ and clinical variables. Time to nadir had a median of 11.5 months and was longer in the first-line group (P = .04).

CONCLUSION

The tumor nadir volume in patients with ALK-rearranged advanced NSCLC treated with alectinib can be predicted by the liner regression model and consists of approximately 30% of the baseline volume minus 5 cm³, providing additional insights into precision therapy monitoring and potential guides for local ablative therapy to prolong disease control.

A multi-modality physical phantom for mimicking tumour heterogeneity patterns in PET/CT and PET/MRI

Background

Hybrid imaging (e.g., positron emission tomography [PET]/computed tomography [CT], PET/magnetic resonance imaging [MRI]) helps one to visualize and quantify morphological and physiological tumor characteristics in a single study. The noninvasive characterization of tumor heterogeneity is essential for grading, treatment planning, and following‐up oncological patients. However, conventional (CONV) image‐based parameters, such as tumor diameter, tumor volume, and radiotracer activity uptake, are insufficient to describe tumor heterogeneities. Here, radiomics shows promise for a better characterization of tumors. Nevertheless, the validation of such methods demands imaging objects capable of reflecting heterogeneities in multi‐modality imaging. We propose a phantom to simulate tumor heterogeneity repeatably in PET, CT, and MRI.

Methods

The phantom consists of three 50‐ml plastic tubes filled partially with acrylic spheres of S1: 1.6 mm, S2: 50%(1.6 mm)/50%(6.3 mm), or S3: 6.3‐mm diameter. The spheres were fixed to the bottom of each tube by a plastic grid, yielding one sphere free homogeneous region and one heterogeneous (S1, S2, or S3) region per tube. A 3‐tube phantom and its replica were filled with a fluorodeoxyglucose (18F) solution for test–retest measurements in a PET/CT Siemens TPTV and a PET/MR Siemens Biograph mMR system. A number of 42 radiomic features (10 first order and 32 texture features) were calculated for each phantom region and imaging modality. Radiomic features stability was evaluated through coefficients of variation (COV) across phantoms and scans for PET, CT, and MRI. Further, the Wilcoxon test was used to assess the capability of stable features to discriminate the simulated phantom regions.

Results

The different patterns (S1–S3) did present visible heterogeneity in all imaging modalities. However, only for CT and MRI, a clear visual difference was present between the different patterns. Across all phantom regions in PET, CT, and MR images, 10, 16, and 21 features out of 42 evaluated features in total had a COV of 10% or less. In particular, CONV, histogram, and gray‐level run length matrix features showed high repeatability for all the phantom regions and imaging modalities. Several of repeatable texture features allowed the image‐based discrimination of the different phantom regions (p < 0.05). However, depending on the feature, different pattern discrimination capabilities were found for the different imaging modalities.

Conclusion

The proposed phantom appears suitable for simulating heterogeneities in PET, CT, and MRI. We demonstrate that it is possible to select radiomic features for the readout of the phantom. Most of these features had been shown to be relevant in previous clinical studies.

Tumor Growth Rate After Nadir Is Associated With Survival in Patients With EGFR-Mutant Non-Small-Cell Lung Cancer Treated With Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor

PURPOSE

To investigate the association between tumor volume growth rate after the nadir and survival in patients with EGFR-mutant advanced non-small-cell lung cancer (NSCLC) treated with erlotinib.

MATERIALS AND METHODS

Seventy-one patients with EGFR-mutant advanced NSCLC treated with erlotinib were studied for computed tomography tumor volume kinetics during therapy. The tumor growth rate after nadir was obtained using a previously published analytic module for longitudinal volume tracking to study its relationship with overall survival (OS).

RESULTS

The median tumor volume for the cohort was 19,842 mm3 at baseline and 4,083 mm3 at nadir. The median time to nadir was 6.2 months. The tumor growth rate after nadir for logeV (the natural logarithm of tumor volume measured in mm3) was 0.11/mo on average for the cohort (SE: 0.014), which was very similar to the previously validated reference value of 0.12/mo to define slow and fast tumor growth. The OS of 48 patients with slow tumor growth (≤ 0.12/mo) was significantly longer compared with 23 patients with fast tumor growth (> 0.12/mo; median OS: 37.8 v 25.0 months; P = .0012). In Cox models, tumor growth rate was also associated with survival (regression coefficient: 3.9903; P = .0024; faster rate leads to increased hazards), after adjusting for time to nadir (regression coefficient: -0.0863; P = .0008; longer time to nadir leads to decreased hazards) and smoking history.

CONCLUSION

In patients with EGFR-mutant advanced NSCLC treated with erlotinib, slower tumor growth rates after nadir were associated with longer OS, providing a rationale for using tumor growth rates to guide precision therapy for lung cancer.

Tumor Growth Rate After Nadir Is Associated With Survival in Patients With EGFR-Mutant Non-Small-Cell Lung Cancer Treated With Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor

PURPOSE

To investigate the association between tumor volume growth rate after the nadir and survival in patients with EGFR-mutant advanced non-small-cell lung cancer (NSCLC) treated with erlotinib.

MATERIALS AND METHODS

Seventy-one patients with EGFR-mutant advanced NSCLC treated with erlotinib were studied for computed tomography tumor volume kinetics during therapy. The tumor growth rate after nadir was obtained using a previously published analytic module for longitudinal volume tracking to study its relationship with overall survival (OS).

RESULTS

The median tumor volume for the cohort was 19,842 mm³ at baseline and 4,083 mm³ at nadir. The median time to nadir was 6.2 months. The tumor growth rate after nadir for log_eV (the natural logarithm of tumor volume measured in mm³) was 0.11/mo on average for the cohort (SE: 0.014), which was very similar to the previously validated reference value of 0.12/mo to define slow and fast tumor growth. The OS of 48 patients with slow tumor growth (≤ 0.12/mo) was significantly longer compared with 23 patients with fast tumor growth (> 0.12/mo; median OS: 37.8 v 25.0 months; P = .0012). In Cox models, tumor growth rate was also associated with survival (regression coefficient: 3.9903; P = .0024; faster rate leads to increased hazards), after adjusting for time to nadir (regression coefficient: -0.0863; P = .0008; longer time to nadir leads to decreased hazards) and smoking history.

CONCLUSION

In patients with EGFR-mutant advanced NSCLC treated with erlotinib, slower tumor growth rates after nadir were associated with longer OS, providing a rationale for using tumor growth rates to guide precision therapy for lung cancer.

A Model-Strengthened Imaging Biomarker for Survival Prediction in EGFR-Mutated Non-small-cell Lung Carcinoma Patients Treated with Tyrosine Kinase Inhibitors

Non-small-cell lung carcinoma is a frequent type of lung cancer with a bad prognosis. Depending on the stage and genomics, several therapeutical approaches are used. Tyrosine Kinase Inhibitors (TKI) may be successful for a time in the treatment of EGFR-mutated non-small cells lung carcinoma. Our objective is here to introduce a survival assessment as their efficacy in the long run is challenging to evaluate. The study includes 17 patients diagnosed with EGFR-mutated non-small cell lung cancer and exposed to an EGFR-targeting TKI with 3 computed tomography (CT) scans of the primary tumor (one before the TKI introduction and two after). An imaging biomarker based on evolution of texture heterogeneity between the first and the third exams is derived and computed from a mathematical model and patient data. Defining the overall survival as the time between the introduction of the TKI treatment and the patient death, we obtain a statistically significant correlation between the overall survival and our imaging marker ([Formula: see text]). Using the ROC curve, the patients are separated into two populations and the comparison of the survival curves is statistically significant ([Formula: see text]). The baseline exam seems to have a significant role in the prediction of response to TKI treatment. More precisely, our imaging biomarker defined using only the CT scan before the TKI introduction allows to determine a first classification of the population which is improved over time using the imaging marker as soon as more CT scans are available. This exploratory study leads us to think that it is possible to obtain a survival assessment using only few CT scans of the primary tumor.

Diffusion-weighted MRI improves response assessment after definitive radiotherapy in patients with NSCLC

Background

Computed tomography (CT) is the standard procedure for follow-up of non-small-cell lung cancer (NSCLC) after radiochemotherapy. CT has difficulties differentiating between tumor, atelectasis and radiation induced lung toxicity (RILT). Diffusion-weighted imaging (DWI) may enable a more accurate detection of vital tumor tissue. The aim of this study was to determine the diagnostic value of MRI versus CT in the follow-up of NSCLC.

Methods

Twelve patients with NSCLC stages I-III scheduled for radiochemotherapy were enrolled in this prospective study. CT with i.v. contrast agent and non enhanced MRI were performed before and 3, 6 and 12 months after treatment. Standardized ROIs were used to determine the apparent diffusion weighted coefficient (ADC) within the tumor. Tumor size was assessed by the longest longitudinal diameter (LD) and tumor volume on DWI and CT. RILT was assessed on a 4-point-score in breath-triggered T2-TSE and CT.

Results

There was no significant difference regarding LD and tumor volume between MRI and CT (p ≥ 0.6221, respectively p ≥ 0.25). Evaluation of RILT showed a very high correlation between MRI and CT at 3 (r = 0.8750) and 12 months (r = 0.903). Assessment of the ADC values suggested that patients with a good tumor response have higher ADC values than non-responders.

Conclusions

DWI is equivalent to CT for tumor volume determination in patients with NSCLC during follow up. The extent of RILT can be reliably determined by MRI. DWI could become a beneficial method to assess tumor response more accurately. ADC values may be useful as a prognostic marker.

Tumor Volume Analysis as a Predictive Marker for Prolonged Survival in Anaplastic Lymphoma Kinase-rearranged Advanced Non-Small Cell Lung Cancer Patients Treated With Crizotinib

PURPOSE

Targeted inhibition of anaplastic lymphoma kinase (ALK) has been widely used for the treatment of advanced non-small cell lung cancer (NSCLC) with ALK rearrangements. We performed tumor volume analysis of ALK-rearranged advanced NSCLC treated with crizotinib to identify an early predictive marker for prolonged survival.

MATERIALS AND METHODS

Cases of 42 patients with ALK-rearranged advanced NSCLC (16 men, 26 women; median age: 55.7 y) treated with crizotinib as their first ALK-directed therapy were retrospectively studied. Tumor volume measurements of dominant lung lesions were performed on baseline computed tomography and follow-up computed tomography at 8 weeks of therapy. The relationships between the 8-week volume change (%) and overall survival (OS) were investigated.

RESULTS

The 8-week tumor volume change ranged from -99.3% to 117.5% (median: -57.7%). Using the 25th percentile of the 8-week volume change of -74%, 11 patients with >74% volume decrease at 8 weeks had a significantly longer OS compared with 31 patients with ≤74% decrease (median OS: 92.0 vs. 22.8 mo; P=0.0048). In multivariable analyses using Cox proportional hazards models, the 8-week volume decrease of >74% was significantly associated with longer OS (hazard ratio=0.14, 95% confidence interval: 0.03-0.59; Cox P=0.008) after adjusting for tumor stage (stage IV vs. recurrent NSCLC, hazard ratio=5.6, 95% confidence interval: 1.29-24.3; P=0.02).

CONCLUSIONS

The 8-week tumor volume decrease of >74% is significantly associated with longer OS in patients with ALK-rearranged NSCLC treated with crizotinib.

Tumor volume dynamics and tumor growth rate in ALK-rearranged advanced non-small-cell lung cancer treated with crizotinib

Purpose

The purpose of the study is to investigate volumetric tumor burden dynamics and tumor growth rates in ALK-rearranged advanced NSCLC patients during crizotinib monotherapy.

Methods

The study included 44 ALK-rearranged advanced NSCLC patients treated with crizotinib monotherapy as their initial ALK-directed therapy, who had at least one measurable lung lesion and at least two follow-up CT scans, and experienced tumor volume increase while on crizotinib. The tumor volume (in mm³) of the dominant lung lesion was measured on serial CT scans during therapy for analysis of tumor growth rates after the volume nadir.

Results

A total of 231 volume measurements from the nadir to the end of crizotinib therapy or the last follow-up in 44 patients were analyzed in a linear mixed-effects model, fitting time (in months since baseline) as a random effect. When measured from the volume nadir, the tumor growth rate of the logarithm of tumor volume (log_eV) was 0.04/month (SE = 0.012, P = 0.0011) in the unadjusted model. When adjusted for the baseline volume (log_eV₀), the growth rate was again 0.04/month (SE = 0.011, P = 0.0004). When adjusted for clinical variables and log_eV₀, the growth rate was 0.045/month (SE = 0.012, P = 0.0002), indicating that the tumor growth rate after nadir in this cohort remains very close to 0.04/month regardless of log_eV₀ or clinical factors.

Conclusions

Tumor volume growth rate after nadir in ALK-rearranged NSCLC patients treated with crizotinib was obtained, providing objective reference values that can inform physicians when deciding to keep their patients on ALK directed therapy with slowly progressing lung cancer.

Pseudoprogression and hyperprogression in lung cancer: a comprehensive review of literature

PURPOSE

Immune checkpoint inhibitors are associated with clinical benefit in lung cancer. However, response patterns to immunotherapy, including pseudoprogression and hyperprogression, are difficult to diagnose, and their mechanisms remain unclear. This review aimed to describe two response patterns observed in lung cancer, namely pseudoprogression and hyperprogression, including their epidemiology, diagnostic characteristics, and plausible mechanisms.

METHODS

We performed a comprehensive literature search in the PubMed database, using keywords "pseudoprogression", "hyperprogression", and "lung cancer", among others. The literature was examined for pseudoprogression and hyperprogression characteristics and plausible mechanisms.

RESULTS

Pseudoprogression manifests in multiple forms; however, the immune system-related response criteria and biopsy data are helpful to make accurate diagnosis. Serological biomarkers, such as neutrophil-to-lymphocyte ratio (NLR) and circulating tumor DNA (ctDNA), might help distinguish pseudoprogression from true progression. The incidence of hyperprogression ranges within 5-19.2%, depending on definition. The unique response pattern of rapid progression is observed not only with immunotherapy, but also with other treatment regimens. Molecular mutations and amplifications may result in hyperprogression; however, the exact mechanism remains unclear.

CONCLUSION

Atypical response patterns, such as pseudoprogression and hyperprogression, are increasingly common in clinical practice. Immune-related response criteria can help diagnose pseudoprogression. Molecular mechanisms of hyperprogression remain unclear. Biomarkers for pseudoprogression and hyperprogression are required.

Volumetric tumor response assessment is inefficient without overt clinical benefit compared to conventional, manual veterinary response assessment in canine nasal tumors

Accurate assessment of tumor response to therapy is critical in guiding management of veterinary oncology patients and is most commonly performed using response evaluation criteria in solid tumors criteria. This process can be time consuming and have high intra- and interobserver variability. The primary aim of this serial measurements, secondary analysis study was to compare manual linear tumor response assessment to semi-automated, contoured response assessment in canine nasal tumors. The secondary objective was to determine if tumor measurements or clinical characteristics, such as stage, would correlate to progression-free interval. Three investigators evaluated paired CT scans of skulls of 22 dogs with nasal tumors obtained prior to and following radiation therapy. The automatically generated tumor volumes were not useful for canine nasal tumors in this study, characterized by poor intraobserver agreement between automatically generated contours and hand-adjusted contours. The radiologist's manual linear method of determining response evaluation criteria in solid tumors categorization and tumor volume is significantly faster (P < .0001) but significantly underestimates nasal tumor volume (P < .05) when compared to a contour-based method. Interobserver agreement was greater for volume determination using the contour-based method when compared to response evaluation criteria in solid tumors categorization utilizing the same method. However, response evaluation criteria in solid tumors categorization and percentage volume change were strongly correlated, providing validity to response evaluation criteria in solid tumors as a rapid method of tumor response assessment for canine nasal tumors. No clinical characteristics or tumor measurements were significantly associated with progression-free interval.

Tumor volume is more reliable to predict nodal metastasis in non-small cell lung cancer of 3.0 cm or less in the greatest tumor diameter

Background

In this study, we sought to evaluate the correlation between TV, GTD, and lymph node metastases in NSCLC patients with tumors of GTD ≤ 3.0 cm.

Methods

We retrospectively analyzed the characteristics of clinicopathologic variables for lymph node involvement in 285 NSCLC patients with tumors of GTD ≤ 3.0 cm who accepted curative surgical resection. The TVs were semi-automatically measured by a software, and optimal cutoff points were obtained using the X-tile software. The relationship between GTD and TV were described using non-linear regression. The correlation between GTD, TV, and N stages was analyzed using the Pearson correlation coefficient. The one-way ANOVA was used to compare the GTD and TV of different lymph node stage groups.

Results

The relationship between GTD and TV accorded with the exponential growth model: y = 0.113e^1.455x (y = TV, x = GTD). TV for patients with node metastases (4.78 cm³) was significantly greater than those without metastases (3.57 cm³) (P < 0.001). However, there were no obvious GTD differences in cases with or without lymph node metastases (P = 0.054). We divided all cases into three TV groups using the two cutoff values (0.9 cm³ and 3.9 cm³), and there was an obvious difference in the lymphatic involvement rate between the groups (P < 0.001). The tendency to metastasize was greater with higher TV especially when the TV was > 0.9–14.2 cm³ (P = 0.010).

Conclusions

For NSCLC tumors with GTD ≤ 3.0 cm, TV is a more sensitive marker than GTD in predicting the positive lymph node metastases. The likelihood for metastasis increases with an increasing TV especially when GTD is > 2.0–3.0 cm.

Correlation between initial tumour volume and treatment duration on Dabrafenib: observation study of subjects with BRAF mutant melanoma on the BRF112680 trial

BACKGROUND

Planar-based measurements of lesions in metastatic melanoma have limitations in estimating tumor burden of a patient and in predicting response to treatment. Volumetric imaging might add predictive value to Response criteria in Solid Tumor (RECIST)-measurement. Based on clinical observations, we explored the association between baseline tumor volume (TV) and duration of treatment with dabrafenib in patients with metastatic melanoma. We have also explored the prognostic value of TV for overall survival (OS) and progression free survival (PFS).

METHODS

This is a retrospective, chart-review of primary source documents and medical imaging of a cohort of patients participating in the BRF112680 phase 1 clinical trial at the Prince of Wales Hospital. TV was quantified by contouring all the measurable baseline target lesions in the standard manner for radiation planning using Voxxar™ software. We used Cox regression models to analyse associations between TV and duration of treatment with dabrafenib and between TV, PFS and OS.

RESULTS

Among 13 patients of BRAF 112680 trial, 10 were included in the retrospective analysis. Target lesion sum volume ranged from 0.3 to 1065.5 cm³ (cc), with a median of 27.5 cc. The median PFS and OS were 420 days (range 109-1765) and 1680 days (range 390-2940), respectively. The initial TV was inversely correlated with duration of treatment with dabrafenib (rho - 0.6; P 0.03). In multivariate analysis, TV was a predictor for OS (HR 2.81 CI 1.06-6.19) and PFS (8.76 (CI 1.05-43.58). Patients with tumour volume above the median had significantly lower OS of 6-months compared to 56-months survival for patients with smaller volumes; P = 0.019.

CONCLUSIONS

TV is a predictor for treatment duration and is prognostic of OS and PFS in patients with metastatic melanoma. These findings need to be validated prospectively in clinical trials.

The impact of quantitative CT-based tumor volumetric features on the outcomes of patients with limited stage small cell lung cancer

INTRODUCTION

Limited stage small cell lung cancer (LS-SCLC) has a poor prognosis. Additional prognostic markers are needed for risk-stratification and treatment intensification. This study compares quantitative CT-based volumetric tumor measurements versus International Association for the Study of Lung Cancer (IASLC) TNM staging to predict outcomes.

MATERIALS & METHODS

A cohort of 105 patients diagnosed with LS-SCLC and treated with chemoradiation (CRT) from 2000 to 2013 were analyzed retrospectively. Patients were staged by the Union for International Cancer Control (UICC) TNM Classification, 8th edition. Tumor volumes and diameters were extracted from radiation planning CT imaging. Univariable and multivariable models were used to analyze relationships between CT features and overall survival (OS), locoregional recurrence (LRR), in-field LRR, any progression, and distant metastasis (DM).

RESULTS

Median follow-up was 21.3 months. Two-year outcomes were as follows: 38% LRR, 31% in-field LRR, 52% DM, 62% any progression, and 47% OS (median survival 16.5 months). On univariable analysis, UICC T-stage and N-stage were not associated with any clinical outcome. UICC overall stage was only statistically associated with in-field LRR. One imaging feature (3D maximum tumor diameter) was found to be significantly associated with LRR (HR 1.10, p = 0.003), in-field LRR (HR 1.10, p = 0.007), DM (HR 1.10, p = 0.02), any progression (HR 1.10, p = 0.008), and OS (HR 1.10, p = 0.03). On multivariable analysis, this feature remained significantly associated with all outcomes.

CONCLUSION

For LS-SCLC, quantitative CT-based volumetric tumor measurements were significantly associated with outcomes after CRT and may be better predictors of outcome than TNM stage.

Measurement Variability in Treatment Response Determination for Non-Small Cell Lung Cancer: Improvements Using Radiomics

Multimodality imaging measurements of treatment response are critical for clinical practice, oncology trials, and the evaluation of new treatment modalities. The current standard for determining treatment response in non-small cell lung cancer (NSCLC) is based on tumor size using the RECIST criteria. Molecular targeted agents and immunotherapies often cause morphological change without reduction of tumor size. Therefore, it is difficult to evaluate therapeutic response by conventional methods. Radiomics is the study of cancer imaging features that are extracted using machine learning and other semantic features. This method can provide comprehensive information on tumor phenotypes and can be used to assess therapeutic response in this new age of immunotherapy. Delta radiomics, which evaluates the longitudinal changes in radiomics features, shows potential in gauging treatment response in NSCLC. It is well known that quantitative measurement methods may be subject to substantial variability due to differences in technical factors and require standardization. In this review, we describe measurement variability in the evaluation of NSCLC and the emerging role of radiomics.

Small Cell Lung Cancer Therapeutic Responses Through Fractal Measurements: From Radiology to Mitochondrial Biology

Small cell lung cancer (SCLC) is an aggressive neuroendocrine disease with an overall 5 year survival rate of ~7%. Although patients tend to respond initially to therapy, therapy-resistant disease inevitably emerges. Unfortunately, there are no validated biomarkers for early-stage SCLC to aid in early detection. Here, we used readouts of lesion image characteristics and cancer morphology that were based on fractal geometry, namely fractal dimension (FD) and lacunarity (LC), as novel biomarkers for SCLC. Scanned tumors of patients before treatment had a high FD and a low LC compared to post treatment, and this effect was reversed after treatment, suggesting that these measurements reflect the initial conditions of the tumor, its growth rate, and the condition of the lung. Fractal analysis of mitochondrial morphology showed that cisplatin-treated cells showed a discernibly decreased LC and an increased FD, as compared with control. However, treatment with mdivi-1, the small molecule that attenuates mitochondrial division, was associated with an increase in FD as compared with control. These data correlated well with the altered metabolic functions of the mitochondria in the diseased state, suggesting that morphological changes in the mitochondria predicate the tumor’s future ability for mitogenesis and motogenesis, which was also observed on the CT scan images. Taken together, FD and LC present ideal tools to differentiate normal tissue from malignant SCLC tissue as a potential diagnostic biomarker for SCLC.

Tumor Volume Is Better Than Diameter for Predicting the Prognosis of Patients with Early-Stage Non-small Cell Lung Cancer

BACKGROUND

This study aimed to investigate whether tumor volume (TV) is better than diameter for predicting the prognosis of patients with early-stage non-small cell lung cancer (NSCLC) after complete resection.

METHODS

This study retrospectively reviewed the clinicopathologic characteristics of 274 patients with early-stage NSCLC who had received pretreatment computed tomography (CT) scans and complete resection. TV was semi-automatically measured from CT scans using an imaging software program. The optimal cutoff of TV was determined by X-tile software. Disease-free survival (DFS) and overall survival (OS) were assessed by the Kaplan-Meier method. The prognostic significance of TV and other variables was assessed by Cox proportional hazards regression analysis.

RESULTS

Using 3.046 cm³ and 8.078 cm³ as optimal cutoff values of TV, the patients were separated into three groups. A larger TV was significantly associated with poor DFS and OS in the multivariable analysis. Kaplan-Meier curves of DFS and OS showed significant differences on the basis of TV among patients with stage 1a disease, greatest tumor diameter (GTD) of 2 cm or smaller, and GTD of 2-3 cm, respectively. Using two TV cutoff points, three categories of TV were created. In 54 cases (19.7%), patients migrated from the GTD categories of 2 cm or smaller, 2-3 cm, and larger than 3 cm into the TV categories of 3.046 cm³ or smaller, 3.046-8.078 cm³, and larger than 8.078 cm³.

CONCLUSION

TV is an independent prognostic factor of DFS and OS for early-stage NSCLC. The findings show that TV is better than GTD for predicting the prognosis of patients with early-stage NSCLC.

Imaging of Cancer Immunotherapy: Current Approaches and Future Directions

Cancer immunotherapy using immune-checkpoint inhibitors has emerged as an effective treatment option for a variety of advanced cancers in the past decade. Because of the distinct mechanisms of immunotherapy that activate the host immunity to treat cancers, unconventional immune-related phenomena are encountered in terms of tumor response and progression, as well as drug toxicity. Imaging plays an important role in objectively characterizing immune-related tumor responses and progression and in detecting and monitoring immune-related adverse events. Moreover, emerging data suggest a promise for molecular imaging that can visualize the specific target molecules involved in immune-checkpoint pathways. In this article, the background and current status of cancer immunotherapy are summarized, and the current methods for imaging evaluations of immune-related responses and toxicities are reviewed along with their limitations and pitfalls. Emerging approaches with molecular imaging are also discussed as a future direction to address unmet needs.

Tumor Response Assessment for Precision Cancer Therapy: Response Evaluation Criteria in Solid Tumors and Beyond

Objective assessment of tumor responses and treatment results has been the basis for the advancement of cancer therapies, and imaging plays a key role to provide a "common language" to describe the results of cancer treatment. Although Response Evaluation Criteria in Solid Tumors (RECIST) has been the most widely accepted method for assessing tumor response in the past decades, the limitations of RECIST have increasingly becoming recognized, especially with the recent advances of precision-medicine approaches to cancer. This article reviews the current concept of tumor response evaluations based on RECIST, describes the limitations of RECIST, and proposes strategies to overcome the limitations. The article emphasizes specific limitations in the setting of precision cancer therapy and cancer immunotherapy and discusses the important insights provided by the cutting-edge investigations in the emerging fields.

Automated image analysis tool for tumor volume growth rate to guide precision cancer therapy: EGFR-mutant non-small-cell lung cancer as a paradigm

PURPOSE

To develop an automated analytic module for calculation of tumor growth rate from serial CT scans and to apply the module and evaluate reproducibility in a pilot cohort of advanced NSCLC patients with EGFR mutations treated with EGFR tyrosine kinase inhibitors.

MATERIALS AND METHODS

The module utilized a commercially available image-processing workstation equipped with a validated tumor volume measurement tool. An automated analytic software module was programmed with the capability to record and display serial tumor volume changes and to calculate tumor volume growth rate over time and added to the workstation. The module was applied to evaluate the tumor growth rate in a pilot cohort of 24 EGFR-mutant patients treated with EGFR inhibitors, and reproducibility references as tested by two independent thoracic radiologists.

RESULTS

The module analyzed chest CT scans from 24 patients (5 males, 19 females; median age: 61) with a median of 8 scans per patient, totaling 227 scans and provided a graphical display with an automated and instant calculation of tumor growth rate after the nadir volume for each patient. High inter and intraobserver agreements were noted for tumor growth rates, with concordance correlation coefficients of 0.9323 and 0.9668, respectively. Interpretation of slow versus fast tumor growth using previously identified threshold of ≤0.15/month had a perfect interobserver agreement (κ = 1.00), and an excellent intraobserver agreement (κ = 0.895).

CONCLUSIONS

The present study describes the development of an image analytic module for assessing tumor growth rate and the data demonstrates the functionality and reproducibility of the module in a pilot cohort of EGFR-mutant NSCLC patients treated with EGFR-TKI. The image analytic module is an initial step for clinical translation of the tumor growth rate approach to guide cancer treatment in precision oncology.

Volumetric MRI Analysis of Plexiform Neurofibromas in Neurofibromatosis Type 1: Comparison of Two Methods

OBJECTIVES

Plexiform neurofibromas (PNs) are complex, histologically benign peripheral nerve sheath tumors that are challenging to measure by simple line measurements. Computer-aided volumetric segmentation of PN has become the recommended method to assess response in clinical trials directed at PN. Different methods for volumetric analysis of PN have been developed. The goal of this study is to test the level of agreement in volume measurements and in interval changes using two separate methods of volumetric magnetic resonance imaging analysis.

METHODS

Three independent volume measurements were performed on 15 PN imaged at three time-points using 3DQI software at Massachusetts General Hospital (MGH) and National Cancer Institute (NCI) and MEDx software at NCI.

RESULTS

Median volume differences at each time-point comparing MGH-3DQI and NCI-3DQI were -0.5, -4.2, and -19.9 mL; comparing NCI-3DQI and NCI-MEDx were -21.0, -47.0, and -21.0 mL; comparing MGH-3DQI and NCI-MEDx were -10.0, -70.3, and -29.9 mL. Median differences in percentage change over time comparing MGH-3DQI and NCI-3DQI were -1.7, 1.1, and -1.0%; comparing NCI-3DQI and NCI-MEDx were -2.3, 3.3, and -1.1%; comparing MGH-3DQI and NCI-MEDx were -0.4, 2.0, and -1.5%. Volume differences were <20% of the mean of the two measurements in 117 of 135 comparisons (86.7%). Difference in interval change was <20% in 120 of the 135 comparisons (88.9%), while disease status classification was concordant in 115 of 135 comparisons (85.2%).

CONCLUSIONS

The volumes, interval changes, and progression status classifications were in good agreement. The comparison of two volumetric analysis methods suggests no systematic differences in tumor assessment. A prospective comparison of the two methods is planned.

Immune-Modified Response Evaluation Criteria In Solid Tumors (imRECIST): Refining Guidelines to Assess the Clinical Benefit of Cancer Immunotherapy

Purpose Treating solid tumors with cancer immunotherapy (CIT) can result in unconventional responses and overall survival (OS) benefits that are not adequately captured by Response Evaluation Criteria In Solid Tumors (RECIST) v1.1. We describe immune-modified RECIST (imRECIST) criteria, designed to better capture CIT responses. Patients and Methods Atezolizumab data from clinical trials in non-small-cell lung cancer, metastatic urothelial carcinoma, renal cell carcinoma, and melanoma were evaluated. Modifications to imRECIST versus RECIST v1.1 included allowance for best overall response after progressive disease (PD) and changes in PD definitions per new lesions (NLs) and nontarget lesions. imRECIST progression-free survival (PFS) did not count initial PD as an event if the subsequent scan showed disease control. OS was evaluated using conditional landmarks in patients whose PFS differed by imRECIST versus RECIST v1.1. Results The best overall response was 1% to 2% greater, the disease control rate was 8% to 13% greater, and the median PFS was 0.5 to 1.5 months longer per imRECIST versus RECIST v1.1. Extension of imRECIST PFS versus RECIST v1.1 PFS was associated with longer or similar OS. Patterns of progression analysis revealed that patients who developed NLs without target lesion (TL) progression had a similar or shorter OS compared with patients with RECIST v1.1 TL progression. Patients infrequently experienced a spike pattern (TLs increase, then decrease) but had longer OS than patients without TL reversion. Conclusion Evaluation of PFS and patterns of response and progression revealed that allowance for TL reversion from PD per imRECIST may better identify patients with OS benefit. Progression defined by the isolated appearance of NLs, however, is not associated with longer OS. These results may inform additional modifications to radiographic criteria (including imRECIST) to better reflect efficacy with CIT agents.

Critical features and challenges associated with imaging in patients undergoing cancer immunotherapy

Manipulating an individual's immune system through immune checkpoint blockade is revolutionizing the paradigms of cancer treatment. Peculiar patterns and kinetics of response have been observed with these new drugs, rendering the assessment of tumor burden particularly challenging in cancer immunotherapy. The mechanisms of action for immune checkpoint blockade, based upon engagement of the adaptive immune system, can generate unusual response patterns, including pseudoprogression, hyperprogression, atypical and delayed responses. In patients treated with immune checkpoint blockade and radiotherapy, a reduction in tumor burden at metastatic sites distant from the irradiation field (abscopal effect) has been observed, with synergistic systemic immune effects provoked by this combination. New toxicities have also been observed, due to excessive immune activity in several organs, including lung, colon, liver and endocrine glands. Efforts to standardize assessment of cancer immunotherapy responses include novel consensus guidelines derived by modifying World Health Organization (WHO) and Response Evaluation Criteria In Solid Tumors (RECIST) criteria. The aim of this review is to evaluate imaging techniques currently used routinely in the clinic and those being used as investigational tools in immunotherapy clinical trials.

Tumor Response Dynamics of Advanced Non-small Cell Lung Cancer Patients Treated with PD-1 Inhibitors: Imaging Markers for Treatment Outcome

Purpose: We evaluated tumor burden dynamics in patients with advanced non-small cell lung cancer (NSCLC) treated with commercial PD-1 inhibitors to identify imaging markers associated with improved overall survival (OS).Experimental Design: The study included 160 patients with advanced NSCLC treated with commercial nivolumab or pembrolizumab monotherapy as a part of clinical care. Tumor burden dynamics were studied for the association with OS.Results: Tumor burden change at best overall response (BOR) ranged from -100% to +278% (median, +3.5%). Response rate (RR) was 18% (29/160). Current and former smokers had a higher RR than never smokers (P = 0.04). Durable disease control for at least 6 months was noted in 26 patients (16%), which included 10 patients with stable disease as BOR. Using a landmark analysis, patients with <20% tumor burden increase from baseline within 8 weeks of therapy had longer OS than patients with ≥20% increase (median OS, 12.4 vs. 4.6 months, P < 0.001). Patients with <20% tumor burden increase throughout therapy had significantly reduced hazards of death (HR, 0.24; Cox P < 0.0001) after adjusting for smoking (HR, 0.86; P = 0.61) and baseline tumor burden (HR, 1.55; P = 0.062), even though some patients met criteria for RECIST progression while on therapy. One patient (0.6%) had atypical response pattern consistent with pseudoprogression.Conclusions: Objective response or durable disease control was noted in 24% of patients with advanced NSCLC treated with commercial PD-1 inhibitors. A tumor burden increase of <20% from baseline during therapy was associated with longer OS, proposing a practical marker of treatment benefit. Pseudoprogression is rare in NSCLCs treated with PD-1 inhibitors. Clin Cancer Res; 23(19); 5737-44. ©2017 AACR.

Monitoring immune-checkpoint blockade: response evaluation and biomarker development

Cancer immunotherapy using immune-checkpoint blockade (ICB) has created a paradigm shift in the treatment of advanced-stage cancers. The promising antitumour activity of monoclonal antibodies targeting the immune-checkpoint proteins CTLA-4, PD-1, and PD-L1 led to regulatory approvals of these agents for the treatment of a variety of malignancies. Patients might experience clinical benefits from treatment with these agents, despite unconventional patterns of tumour response that can be misinterpreted as disease progression, warranting a new, specific approach to evaluate responses to immunotherapy. In addition, biomarkers that can predict responsiveness to ICB are being extensively investigated to further advance precision immunotherapy. Herein, we review the biological mechanisms underlying the unconventional response patterns associated with ICB, describe strategies for the objective assessments of such responses, and also highlight the ongoing efforts to identify biomarkers, in order to guide treatment with ICB. We provide state-of-the-art knowledge of immune-related response evaluations, identify unmet needs requiring further investigations, and propose future directions to maximize the benefits of ICB therapy.

Immune-Related Tumor Response Dynamics in Melanoma Patients Treated with Pembrolizumab: Identifying Markers for Clinical Outcome and Treatment Decisions

Purpose: Characterize tumor burden dynamics during PD-1 inhibitor therapy and investigate the association with overall survival (OS) in advanced melanoma.Experimental Design: The study included 107 advanced melanoma patients treated with pembrolizumab. Tumor burden dynamics were assessed on serial CT scans using irRECIST and were studied for the association with OS.Results: Among 107 patients, 96 patients had measurable tumor burden and 11 had nontarget lesions alone at baseline. In the 96 patients, maximal tumor shrinkage ranged from -100% to 567% (median, -18.5%). Overall response rate was 44% (42/96; 5 immune-related complete responses, 37 immune-related partial responses). Tumor burden remained <20% increase from baseline throughout therapy in 57 patients (55%). Using a 3-month landmark analysis, patients with <20% tumor burden increase from baseline had longer OS than patients with ≥20% increase (12-month OS rate: 82% vs. 53%). In extended Cox models, patients with <20% tumor burden increase during therapy had significantly reduced hazards of death [HR = 0.19; 95% confidence interval (CI), 0.08-0.43; P < 0.0001 univariate; HR = 0.18; 95% CI, 0.08-0.41; P < 0.0001, multivariable]. Four patients (4%) experienced pseudoprogression; 3 patients had target lesion increase with subsequent response, which was noted after confirmed immune-related progressive disease (irPD). One patient without measurable disease progressed with new lesion that subsequently regressed.Conclusions: Tumor burden increase of <20% from the baseline during pembrolizumab therapy was associated with longer OS, proposing a practical marker for treatment decision guides that needs to be prospectively validated. Pseudoprogressors may experience response after confirmed irPD, indicating a limitation of the current strategy for immune-related response evaluations. Evaluations of patients without measurable disease may require further attention. Clin Cancer Res; 23(16); 4671-9. ©2017 AACR.

Volume Measurement by Diffusion-Weighted Imaging in Cervical Cancer

BACKGROUND

The aim of this paper was to evaluate the validity of tumor volume measurement using diffusion-weighted (DW) imaging in cervical cancer.

METHODS

In this retrospective study, 22 patients, who underwent preoperative 3.0 T MR examinations with DW imaging were evaluated. Tumor volume measurement by oblique axial (short axis to the uterine cervix) T2-weighted imaging was performed by manually outlining the tumor on the monitor. The area of tumor in each slice was multiplied by the slice profile (slice thickness plus intersection gap), and the total tumor volume was calculated by summation of these obtained volumes. Meanwhile, one experienced radiological technologist generated three-dimensional DW images of cervical cancer using a volume-rendering algorithm at a computer workstation, and tumor volume was automatically calculated in the workstation. Analysis via the intraclass correlation coefficient (ICC) and Bland-Altman plots were used to assess the validity and reliability of these methods.

RESULTS

Between tumor volumes measured by T2-weighted imaging methods and DW imaging methods, the ICC was excellent (0.962). The 95% limits of agreement of volume measurement were -52.7 and 35.7 mL (mean difference, -8.5 mL). In regards to intra-observer variability, the ICC was excellent (0.963). The 95% limits of agreement of volume measurement were -42.2 and 47.4 mL (mean difference, 2.6 mL).

CONCLUSION

DW imaging can be used to measure cervical cancer volume.

Pharmacometric Modeling of Liver Metastases' Diameter, Volume, and Density and Their Relation to Clinical Outcome in Imatinib-Treated Patients With Gastrointestinal Stromal Tumors

Three‐dimensional and density‐based tumor metrics have been suggested to better discriminate tumor response to treatment than unidimensional metrics, particularly for tumors exhibiting nonuniform size changes. In the developed pharmacometric modeling framework based on data from 77 imatinib‐treated gastrointestinal patients, the time‐courses of liver metastases' maximum transaxial diameters, software‐calculated actual volumes (V_actual) and calculated ellipsoidal volumes were characterized by logistic growth models, in which imatinib induced a linear dose‐dependent size reduction. An indirect response model best described the reduction in density. Substantial interindividual variability in the drug effect of all response assessments and additional interlesion variability in the drug effect on density were identified. The predictive ability of longitudinal tumor unidimensional and three‐dimensional size and density on overall survival (OS) and progression‐free survival (PFS) were compared using parametric time‐to‐event models. Death hazard increased with increasing V_actual. This framework may guide early clinical interventions based on three‐dimensional tumor responses to enhance benefits for patients with gastrointestinal stromal tumors (GIST).

Radiogenomic Analysis of Oncological Data: A Technical Survey

In the last few years, biomedical research has been boosted by the technological development of analytical instrumentation generating a large volume of data. Such information has increased in complexity from basic (i.e., blood samples) to extensive sets encompassing many aspects of a subject phenotype, and now rapidly extending into genetic and, more recently, radiomic information. Radiogenomics integrates both aspects, investigating the relationship between imaging features and gene expression. From a methodological point of view, radiogenomics takes advantage of non-conventional data analysis techniques that reveal meaningful information for decision-support in cancer diagnosis and treatment. This survey is aimed to review the state-of-the-art techniques employed in radiomics and genomics with special focus on analysis methods based on molecular and multimodal probes. The impact of single and combined techniques will be discussed in light of their suitability in correlation and predictive studies of specific oncologic diseases.

Diffusion-weighted quantitative MRI of pleural abnormalities: Intra- and interobserver variability in the apparent diffusion coefficient measurements

PURPOSE

To assess intra- and interobserver variability in the apparent diffusion coefficient (ADC) measurements of pleural abnormalities.

MATERIALS AND METHODS

Diffusion-weighted magnetic resonance imaging was performed in 34 patients to characterize pleural abnormalities, with a 1.5T unit at b values of 0/150/500/800 sec/mm² . In two sessions held 3 months apart, on perfusion-free ADC maps, two independent readers measured the ADC of pleural abnormalities (two readings for each reader in each case) using different methods of region-of-interest (ROI) positioning. In three methods, freehand ROIs were drawn within tumor boundaries to encompass the entire lesion on one or more axial slices (whole tumor volume [WTV], three slices observer-defined [TSOD], single-slice [SS]), while in two methods one or more ROIs were placed on the more restricted areas (multiple small round ROI [MSR], one small round ROI [OSR]). Measurement variability between readings by each reader (intraobserver repeatability) and between readers in first reading (interobserver repeatability) were assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CoV). Analysis of variance (ANOVA) was performed to compare ADC values between the different methods. The measurement time of each case for all methods in first reading was recorded and compared between methods and readers.

RESULTS

All methods demonstrated good (MSR, OSR) and excellent (WTV, TSOD, SS) intra- and interreader agreement, with best and worst repeatability in WTV (lower ICC, 0.977; higher CoV, 3.5%) and OSR (lower ICC, 0.625; higher CoV, 22.8%), respectively. The lower 95% confidence interval of ICC resulted in fair to moderate agreement for OSR (up to 0.379) and in excellent agreement for WTV, TSV, and SS (up to 0.918). ADC values of OSR and MSR were significantly lower compared to other methods (P < 0.001). The OSR and SS required less measurement time (10 and 21/22 sec, respectively) compared to the others (P < 0.0001), while the WTV required the longest measurement time (132/134 sec) (P < 0.0001).

CONCLUSION

ADC measurements of pleural abnormalities are repeatable. The SS method has excellent repeatability, similar to WTV, but requires significantly less measurement time. Thus, its use should be preferred in clinical practice.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:769-782.

Decision support systems for personalized and participative radiation oncology

A paradigm shift from current population based medicine to personalized and participative medicine is underway. This transition is being supported by the development of clinical decision support systems based on prediction models of treatment outcome. In radiation oncology, these models 'learn' using advanced and innovative information technologies (ideally in a distributed fashion - please watch the animation: http://youtu.be/ZDJFOxpwqEA) from all available/appropriate medical data (clinical, treatment, imaging, biological/genetic, etc.) to achieve the highest possible accuracy with respect to prediction of tumor response and normal tissue toxicity. In this position paper, we deliver an overview of the factors that are associated with outcome in radiation oncology and discuss the methodology behind the development of accurate prediction models, which is a multi-faceted process. Subsequent to initial development/validation and clinical introduction, decision support systems should be constantly re-evaluated (through quality assurance procedures) in different patient datasets in order to refine and re-optimize the models, ensuring the continuous utility of the models. In the reasonably near future, decision support systems will be fully integrated within the clinic, with data and knowledge being shared in a standardized, dynamic, and potentially global manner enabling truly personalized and participative medicine.

Immune-Checkpoint Inhibitors in the Era of Precision Medicine: What Radiologists Should Know

Over the past five years immune-checkpoint inhibitors have dramatically changed the therapeutic landscape of advanced solid and hematologic malignancies. The currently approved immune-checkpoint inhibitors include antibodies to cytotoxic T-lymphocyte antigen-4, programmed cell death (PD-1), and programmed cell death ligand (PD-L1 and PD-L2). Response to immune-checkpoint inhibitors is evaluated on imaging using the immune-related response criteria. Activation of immune system results in a unique toxicity profile termed immune-related adverse events. This article will review the molecular mechanism, clinical applications, imaging of immune-related response patterns and adverse events associated with immune-checkpoint inhibitors.

Co-clinical quantitative tumor volume imaging in ALK-rearranged NSCLC treated with crizotinib

PURPOSE

To evaluate and compare the volumetric tumor burden changes during crizotinib therapy in mice and human cohorts with ALK-rearranged non-small-cell lung cancer (NSCLC).

METHODS

Volumetric tumor burden was quantified on serial imaging studies in 8 bitransgenic mice with ALK-rearranged adenocarcinoma treated with crizotinib, and in 33 human subjects with ALK-rearranged NSCLC treated with crizotinib. The volumetric tumor burden changes and the time to maximal response were compared between mice and humans.

RESULTS

The median tumor volume decrease (%) at the maximal response was -40.4% (range: -79.5%-+11.7%) in mice, and -72.9% (range: -100%-+72%) in humans (Wilcoxon p=0.03). The median time from the initiation of therapy to maximal response was 6 weeks in mice, and 15.7 weeks in humans. Overall volumetric response rate was 50% in mice and 97% in humans. Spider plots of tumor volume changes during therapy demonstrated durable responses in the human cohort, with a median time on therapy of 13.1 months.

CONCLUSION

The present study described an initial attempt to evaluate quantitative tumor burden changes in co-clinical imaging studies of genomically-matched mice and human cohorts with ALK-rearranged NSCLC treated with crizotinib. Differences are noted in the degree of maximal volume response between the two cohorts in this well-established paradigm of targeted therapy, indicating a need for further studies to optimize co-clinical trial design and interpretation.

Immune-related response evaluations during immune-checkpoint inhibitor therapy: establishing a "common language" for the new arena of cancer treatment

The recent study by Hodi et al. published in the Journal of Clinical Oncology has evaluated unconventional response patterns during PD-1 inhibitor therapy using immune-related response criteria (irRC) in comparison with RECIST1.1, which constitutes an important step to further understand immune-related response phenomena. This commentary discusses the key observations in the study in terms of their implications and pitfalls, and describes unmet needs that remain to be addressed. The article also emphasizes the important role of tumor response criteria as a “common language” to describe the results of cancer treatment, and discusses future directions for further advances of the field of immuno-oncology.

Semiautomatic Analysis on Computed Tomography in Locally Advanced or Metastatic Non-Small Cell Lung Cancer: Reproducibility and Prognostic Significance of Unidimensional and 3-dimensional Measurements

PURPOSE

The aim of the study was to compare both reproducibility and prognostic value of lesion size measurements obtained manually and semiautomatically on computed tomography in advanced non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Manual axial longest diameter, semiautomatic axial longest diameter, and volume of NSCLC lesions were independently analyzed by 4 readers at baseline and after at least 1 cycle of platinum-based chemotherapy. The prognostic value of the proportional change in lesion size between baseline and follow-up CT was evaluated using either RECIST or experimental thresholds derived from the quartiles of the changes as assessed manually or semiautomatically.

RESULTS

Semiautomatic axial longest diameter (concordance correlation coefficient [CCC]: 0.980 to 0.987; variation coefficient [VC%]: 6% to 7.3%) and volume (CCC: 0.974 to 0.991; VC%: 5.6% to 9.5%) were more reproducible than manual axial longest diameter (CCC: 0.950 to 0.984; VC%: 6.4% to 11.7%). RECIST categories did not stratify patients with different survival durations. For 3/4 readers, a decrease of ≤ 70% in lesion volume was associated with shorter survival (median survival: 11 mo, P < 0.05; hazard ratio: 5 to 22.2, P < 0.05).

CONCLUSIONS

In advanced NSCLC, semiautomatic measures were more reproducible than manual diameter, and volumetric measurement may better predict patient survival.

Mechanism and non-mechanism based imaging biomarkers for assessing biological response to treatment in non-small cell lung cancer

Therapeutic options in locally advanced non-small cell lung cancer (NSCLC) have expanded in the past decade to include a palate of targeted interventions such as high dose targeted thermal ablations, radiotherapy and growing platform of antibody and small molecule therapies and immunotherapies. Although these therapies have varied mechanisms of action, they often induce changes in tumour architecture and microenvironment such that response is not always accompanied by early reduction in tumour mass, and evaluation by criteria other than size is needed to report more effectively on response. Functional imaging techniques, which probe the tumour and its microenvironment through novel positron emission tomography and magnetic resonance imaging techniques, offer more detailed insights into and quantitation of tumour response than is available on anatomical imaging alone. Use of these biomarkers, or other rational combinations as readouts of pathological response in NSCLC have potential to provide more accurate predictors of treatment outcomes. In this article, the robustness of the more commonly available positron emission tomography and magnetic resonance imaging biomarker indices is examined and the evidence for their application in NSCLC is reviewed.

Volume-based growth tumor kinetics as a prognostic biomarker for patients with EGFR mutant lung adenocarcinoma undergoing EGFR tyrosine kinase inhibitor therapy: a case control study

BACKGROUND

We aim to determine whether volumetric assessment has the potential to serve as a prognostic biomarker, and to assess the relationship between longitudinal tumor data during treatment and prognosis in lung adenocarcinoma patients with sensitizing EGFR mutations treated with EGFR tyrosine kinase inhibitors (TKI).

METHODS

We retrospectively assessed patients with EGFR-mutant stage IV lung adenocarcinoma who were treated with EGFR TKIs until disease progression. CT studies of 106 patients were quantitatively analyzed in terms of tumor size and volume by comparing baseline and follow-up CT scans obtained at every two treatment cycles. Tumor response was quantified using longitudinal measurements, and tumor growth kinetics was determined. Correlation with early surrogate parameters for tumor response evaluation such as change in size, volume, and response rate was performed. The Cox-proportional hazard model and Log-rank test were used to predict overall survival (OS).

RESULTS

Responders based on the percent change in volume after four cycles of TKI therapy had a higher OS than non-responders (P = 0.035). The percent of volume and size changes after four cycles of TKI therapy were significantly correlated with TTP (P < 0.001).

CONCLUSION

Volume measurements and corresponding rates of growth appear to be helpful adjuncts for predicting survival in patients undergoing EGFR-TKI therapy.

Volumetric Tumor Response and Progression in EGFR-mutant NSCLC Patients Treated with Erlotinib or Gefitinib

RATIONALE AND OBJECTIVES

The aims of this study were to investigate the association between 8-week tumor volume decrease and survival in an independent cohort of epidermal growth factor receptor (EGFR)-mutant advanced non-small cell lung cancer (NSCLC) patients treated with first-line erlotinib or gefitinib, and to assess the rate of their volumetric tumor growth after the volume nadir.

MATERIALS AND METHODS

In patients with advanced NSCLC harboring sensitizing EGFR mutations treated with first-line erlotinib or gefitinib, computed tomography (CT) tumor volumes of dominant lung lesions were analyzed for (1) the association with survival, and (2) the volumetric tumor growth rate after the volume nadir.

RESULTS

In 44 patients with the 8-week follow-up CT, the 8-week tumor volume decrease (%) was significantly associated with longer overall survival when fitted as a continuous variable in a Cox model (P = 0.01). The growth rate of the logarithm of tumor volume (logeV), obtained using a linear mixed-effects model adjusting for time since baseline, was 0.096/month (SE: 0.013/month; 95% confidence interval [CI]: 0.071-0.12/month), which was similar to the rate of 0.12/month (SE: 0.015/month; 95%CI: 0.090-0.15/month) observed in the previous report.

CONCLUSIONS

The 8-week tumor volume decrease was validated as a marker for longer survival in the independent cohort of EGFR-mutant NSCLC patients treated with first-line erlotinib or gefitinib. The volumetric tumor growth rate after the nadir in this cohort was similar to that of the previous cohort, indicating the reproducibility of the observation among different patient cohorts.

Comparison of CT volumetric measurement with RECIST response in patients with lung cancer

PURPOSE

To examine the correlations between uni-dimensional RECIST and volumetric measurements in patients with lung adenocarcinoma and to assess their association with overall survival (OS) and progression-free survival (PFS).

MATERIALS AND METHODS

In this study of patients receiving chemotherapy for lung cancer in the setting of a clinical trial, response was prospectively evaluated using RECIST 1.0. Retrospectively, volumetric measurements were recorded and response was assessed by two different volumetric methods at each followup CT scan using a semi-automated segmentation algorithm. We subsequently evaluated the correlation between the uni-dimensional RECIST measurements and the volumetric measurements and performed landmark analyses for OS and PFS at the completion of the first and second follow-ups. Kaplan-Meier curves together with log-rank tests were used to evaluate the association between the different response criteria and patient outcome.

RESULTS

Forty-two patients had CT scans at baseline, after the first follow up scan and second followup scan, and then every 8 weeks. The uni-dimensional RECIST measurements and volumetric measurements were strongly correlated, with a Spearman correlation coefficient (ρ) of 0.853 at baseline, ρ=0.861 at the first followup, ρ=0.843 at the 2nd followup, and ρ=0.887 overall between-subject. On first follow-up CT, partial responders and non responders as assessed by an "ellipsoid" volumetric criteria showed a significant difference in OS (p=0.008, 1-year OS of 70% for partial responders and 46% for non responders). There was no difference between the groups when assessed by RECIST criteria on first follow-up CT (p=0.841, 1-year OS rate of 64% for partial responders and 64% for non responders).

CONCLUSION

Volumetric response on first follow-up CT may better predict OS than RECIST response.

CLINICAL RELEVANCE STATEMENT

Assessment of tumor size and response is of utmost importance in clinical trials. Volumetric measurements may help to better predict OS than uni-dimensional RECIST criteria.

Observer variability in RECIST-based tumour burden measurements: a meta-analysis

BACKGROUND

Response Evaluation Criteria in Solid Tumours (RECIST)-based tumour burden measurements involve observer variability, the extent of which ought to be determined.

METHODS

A literature search identified studies on observer variability during manual measurements of tumour burdens via computed tomography according to the RECIST guideline. The 95% limit of agreement (LOA) values of relative measurement difference (RMD) were pooled using a random-effects model.

RESULTS

Twelve studies were included. Pooled 95% LOAs of RMD in measuring unidimensional longest diameters of single lesions ranged from -22.1% (95% confidence interval [CI], -30.3% to -14.0%) to 25.4% (95% CI, 17.2% to 33.5%) between observers and -17.8% (95% CI, -23.6% to -11.9%) to 16.1% (95% CI, 10.1% to 21.8%) for a single observer. Pooled 95% LOAs of RMD in measuring the sum of multiple lesions ranged from -19.2% (95% CI, -23.7% to -14.9%) to 19.5% (95% CI, 15.2% to 23.9%) between observers, and -9.8% (95% CI, -19.0% to -0.3%) to 13.1% (95% CI, 3.6% to 22.6%) for a single observer. Pooled 95% LOA of RMD in calculating the interval change of tumour burden with a single lesion ranged from -31.3% (95% CI, -46.0% to -16.5%) to 30.3% (95% CI, 15.3% to 44.8%) between observers. Studies on calculating the interval change of tumour burden for a single observer or with multiple lesions were lacking.

CONCLUSION

Interobserver RMD in measuring single tumour burden and calculating its interval change may exceed the 20% cut-off for progression. Variability decreased when tumour burden was measured by a single observer or assessed by the sum of multiple lesions.

Changes of lung tumour volume on CT - prediction of the reliability of assessments

Background

For oncological evaluations, quantitative radiology gives clinicians significant insight into patients’ response to therapy. In regard to the Response Evaluation Criteria in Solid Tumours (RECIST), the classification of disease evolution partly consists in applying thresholds to the measurement of the relative change of tumour. In the case of tumour volumetry, response thresholds have not yet been established. This study proposes and validates a model for calculating thresholds for the detection of minimal tumour change when using the volume of pulmonary lesions on CT as imaging biomarker.

Methods

Our work is based on the reliability analysis of tumour volume measurements documented by the Quantitative Imaging Biomarker Alliance. Statistics of measurements were entered into a multi-parametric mathematical model of the relative changes derived from the Geary-Hinkley transformation. The consistency of the model was tested by comparing modelled thresholds against Monte Carlo simulations of tumour volume measurements with additive random error. The model has been validated by repeating measurements on real patient follow ups.

Results

For unchanged tumour volume, relying on a normal distribution of error, the agreement between model and simulations featured a type I error of 5.25 %. Thus, we established that a threshold of 35 % of volume reduction corresponds to a partial response (PR) and a 55 % volume increase corresponds to progressive disease (PD). Changes between −35 and +55 % are categorized as stable disease (SD). Tested on real clinical data, 97.1 % [95.7; 98.0] of assessments fall into the range of variability predicted by our model of confidence interval.

Conclusions

Our study indicates that the Geary Hinkley model, using published statistics, is appropriate to predict response thresholds for the volume of pulmonary lesions on CT.

Accuracy and feasibility of estimated tumour volumetry in primary gastric gastrointestinal stromal tumours: validation using semiautomated technique in 127 patients

OBJECTIVES

To validate estimated tumour volumetry in primary gastric gastrointestinal stromal tumours (GISTs) using semiautomated volumetry.

METHODS

In this IRB-approved retrospective study, we measured the three longest diameters in x, y, z axes on CTs of primary gastric GISTs in 127 consecutive patients (52 women, 75 men, mean age 61 years) at our institute between 2000 and 2013. Segmented volumes (Vsegmented) were obtained using commercial software by two radiologists. Estimate volumes (V1-V6) were obtained using formulae for spheres and ellipsoids. Intra- and interobserver agreement of Vsegmented and agreement of V1-6 with Vsegmented were analysed with concordance correlation coefficients (CCC) and Bland-Altman plots.

RESULTS

Median Vsegmented and V1-V6 were 75.9, 124.9, 111.6, 94.0, 94.4, 61.7 and 80.3 cm(3), respectively. There was strong intra- and interobserver agreement for Vsegmented. Agreement with Vsegmented was highest for V6 (scalene ellipsoid, x ≠ y ≠ z), with CCC of 0.96 [95 % CI 0.95-0.97]. Mean relative difference was smallest for V6 (0.6 %), while it was -19.1 % for V5, +14.5 % for V4, +17.9 % for V3, +32.6 % for V2 and +47 % for V1.

CONCLUSION

Ellipsoidal approximations of volume using three measured axes may be used to closely estimate Vsegmented when semiautomated techniques are unavailable.

KEY POINTS

Estimation of tumour volume in primary GIST using mathematical formulae is feasible. Gastric GISTs are rarely spherical. Segmented volumes are highly concordant with three axis-based scalene ellipsoid volumes. Ellipsoid volume can be used as an alternative for automated tumour volumetry.

Cancer immunotherapy and immune-related response assessment: The role of radiologists in the new arena of cancer treatment

The recent advances in the clinical application of anti-cancer immunotherapeutic agents have opened a new arena for the treatment of advanced cancers. Cancer immunotherapy is associated with a variety of important radiographic features in the assessments of tumor response and immune-related adverse events, which calls for radiologists' awareness and in-depth knowledge on the topic. This article will provide the state-of-the art review and perspectives of cancer immunotherapy, including its molecular mechanisms, the strategies for immune-related response assessment on imaging and their pitfalls, and the emerging knowledge of radiologic manifestations of immune-related adverse events. The cutting edge clinical and radiologic investigations are presented to provide future directions.