Radiological assessment of tumour response to anti-cancer drugs: time to reappraise

Quantitative Imaging Assessment for Clinical Trials in Oncology

BACKGROUND

Objective radiographic assessment is crucial for accurately evaluating therapeutic efficacy and patient outcomes in oncology clinical trials. Imaging assessment workflow can be complex; can vary with institution; may burden medical oncologists, who are often inadequately trained in radiology and response criteria; and can lead to high interobserver variability and investigator bias. This article reviews the development of a tumor response assessment core (TRAC) at a comprehensive cancer center with the goal of providing standardized, objective, unbiased tumor imaging assessments, and highlights the web-based platform and overall workflow. In addition, quantitative response assessments by the medical oncologists, radiologist, and TRAC are compared in a retrospective cohort of patients to determine concordance.

PATIENTS AND METHODS

The TRAC workflow includes an image analyst who pre-reviews scans before review with a board-certified radiologist and then manually uploads annotated data on the proprietary TRAC web portal. Patients previously enrolled in 10 lung cancer clinical trials between January 2005 and December 2015 were identified, and the prospectively collected quantitative response assessments by the medical oncologists were compared with retrospective analysis of the same dataset by a radiologist and TRAC.

RESULTS

This study enlisted 49 consecutive patients (53% female) with a median age of 60 years (range, 29-78 years); 2 patients did not meet study criteria and were excluded. A linearly weighted kappa test for concordance for TRAC versus radiologist was substantial at 0.65 (95% CI, 0.46-0.85; standard error [SE], 0.10). The kappa value was moderate at 0.42 (95% CI, 0.20-0.64; SE, 0.11) for TRAC versus oncologists and only fair at 0.34 (95% CI, 0.12-0.55; SE, 0.11) for oncologists versus radiologist.

CONCLUSIONS

Medical oncologists burdened with the task of tumor measurements in patients on clinical trials may introduce significant variability and investigator bias, with the potential to affect therapeutic response and clinical trial outcomes. Institutional imaging cores may help bridge the gap by providing unbiased and reproducible measurements and enable a leaner workflow.

Inter-observer variability of response evaluation criteria for hepatocellular carcinoma treated with chemoembolization

BACKGROUND

Data comparing EASL and mRECIST criteria for response evaluation in treatment of hepatocellular carcinoma are rare. We evaluated inter-observer variability by these two response evaluation criteria in treatment-naïve patients undergoing chemoembolization.

METHODS

For 133 patients undergoing chemoembolization, two radiologists independently measured sum of bi-dimensional and uni-dimensional diameters at baseline using both EASL criteria and mRECIST, and their changes on first follow-up for up to 5 target lesions.

RESULTS

Concordance correlation coefficients for sum of bi-dimensional and uni-dimensional diameters at baseline between two observers were 0.992 and 0.988, respectively. However, those for their changes on follow-up were 0.865 and 0.877, respectively. Similarly, mean differences in sum of bi-dimensional and uni-dimensional diameters at baseline between two observers were small; -0.455 and 0.079 cm, respectively. However, mean differences in changes (%) in sum of bi-dimensional and uni-dimensional diameters on first follow-up between observers increased by -9.715% and -9.320%, respectively. Regarding tumour numbers, kappa-value between observers was 0.942. For treatment response (complete or partial response, stable disease and progression), kappa-value was 0.941 by both criteria. When only up to two target lesions were assessed, kappa-value was 1.000 by both criteria.

CONCLUSIONS

Inter-observer agreements using both response evaluation criteria were excellent, especially when up to two targets were assessed.

Observer variability in a phase II trial - assessing consistency in RECIST application

OBJECTIVE

To assess the consistency of Response Evaluation Criteria in Solid Tumours (RECIST) application in a phase II trial.

MATERIAL AND METHODS

Patients with metastatic non-resectable colorectal cancer treated with a combination of an antibody and a chemotherapeutic drug, were included. Computed tomography (CT) scans (thorax, abdomen and pelvis) were performed at baseline and after every fourth treatment cycle. RECIST was intended for response evaluation. The scans were consecutively read by a heterogeneous group of radiologists as a part of daily work and hereafter retrospectively reviewed by a dedicated experienced radiologist. Agreement on best overall response (BOR) between readers and reviewer was quantified using κ-coefficients and the discrepancy rate was correlated with the number of different readers per patient using a χ(2)-test.

RESULTS

One hundred patients with 396 CT scans were included. Discrepancies between the readers and the reviewer were found in 47 patients. The majority of discrepancies concerned the application of RECIST. With the review, BOR changed in 17 patients, although, only in six patients the change was potentially treatment altering. Overall, the κ-coefficient of agreement between readers and reviewer was 0.71 (good). However, in the subgroup of responding patients the κ-coefficient was 0.21 (fair). The number of patients with discrepancies was significantly higher with three or more different readers per patient than with less (p =0.0003).

CONCLUSION

RECIST was not consistently applied and the majority of the reader discrepancies were RECIST related. Post review, 17 patients changed BOR; six patients in a potentially treatment altering manner. Additionally, we found that the part of patients with discrepancies increased significantly with more than three different readers per patient. The findings support a peer-review approach where a few dedicated radiologists perform double blinded readings of all the on-going cancer trial patients' CT scans.

Metastatic colorectal cancer: current treatment and future options for improved survival. Medical approach--present status

BACKGROUND

Metastatic colorectal cancer has a poor prognosis, and the majority of patients are left with palliative measures. The development seen using medical treatments are reviewed.

MATERIAL AND METHODS

A systematic approach to the literature-based evidence of effects from palliative chemotherapy and targeted drugs was aimed at.

RESULTS

The continuous improvements during the past 20-25 years have been documented in several large conclusive trials. At the end of the 1980s, the evidence that chemotherapy should be used at all was very limited, whereas presently most patients can be offered three lines of chemotherapy with or without a targeted drug based upon good scientific evidence. Median survival in trials has gradually improved from about 6 months to above 24 months in the most recent trials. Survival in the populations has, however, not improved to the same extent. Several important issues remain to be solved, such as the best sequence of treatments, what regimens to use in various situations, when to start and when to stop if a response is seen, whether cure may be possible in a small subset of patients, and socioeconomic issues. Integration of surgery and other local methods have further improved outcome for some individuals, but must be fine-tuned.

CONCLUSIONS

Progress has been rapid in advanced colorectal cancer. This is likely a result of well-designed trials in collaboration between academy and industry, showing a great interest in the disease. A multi-professional approach and future collaborations may hopefully introduce new treatment concepts, further improving outcome.

The initial change in tumor size predicts response and survival in patients with metastatic colorectal cancer treated with combination chemotherapy

BACKGROUND

To determine whether the change in tumor diameters at the first follow-up computed tomography (CT) examination after baseline examination (first change) correlates with outcome in patients with metastatic colorectal cancer (mCRC) treated with combination chemotherapy.

PATIENTS AND METHODS

The first change was analyzed in a multicenter randomized phase III trial (Nordic VI, N = 567) comparing first-line irinotecan with either bolus or infused 5-fluorouracil. Cox proportional hazards multiple regression model and Kaplan-Meier survival analyses after correction for guarantee-time bias were carried out to evaluate correlations between first change, objective response according to RECIST 1.0, progression-free survival (PFS), and overall survival (OS).

RESULTS

The hazard ratios for PFS and OS decreased along with first change. A decrease between 10% and <30%, albeit RECIST does not regard this as a partial response, was a positive prognostic factor for PFS and OS. Patients who had new lesions or unequivocal progression of nonmeasurable lesions had a worse prognosis than those with only an increase in size of >20%.

CONCLUSIONS

The change in tumor size at the first follow-up CT is strongly prognostic for PFS and OS in mCRC.

Interobserver and intraobserver variability in the response evaluation of cancer therapy according to RECIST and WHO-criteria

BACKGROUND

Response Evaluation Criteria In Solid Tumors (RECIST) and WHO-criteria are used to evaluate treatment effects in clinical trials. The purpose of this study was to examine interobserver and intraobserver variations in radiological response assessment using these criteria.

MATERIAL AND METHODS

Thirty-nine patients were eligible. Each patient's series of CT images were reviewed. Each patient was classified into one of four categories according RECIST and WHO-criteria. To examine interobserver variation, response classifications were independently obtained by two radiologists. One radiologist repeated the procedure on two additional different occasions to examine intraobserver variation. Kappa statistics was applied to examine agreement.

RESULTS

Interobserver variation using RECIST and WHO-criteria were 0.53 (95% CI 0.33-0.72) and 0.60 (0.39-0.80), respectively. Response rates (RR) according to RECIST obtained by reader A and reader B were 33% and 21%, respectively. RR according to WHO-criteria obtained by reader A and reader B were 33% and 23% respectively. Intraobserver variation using RECIST and WHO-criteria ranged between 0.76-0.96 and 0.86-0.91, respectively.

CONCLUSION

Radiological tumor response evaluation according to RECIST and WHO-criteria are subject to considerable inter- and intraobserver variability. Efforts are necessary to reduce inconsistencies from current response evaluation criteria.