Prognostic value of different CT measurements in early therapy response evaluation in patients with metastatic colorectal cancer

Abstract

Objectives: Patients with advanced stage colorectal carcinoma (CRC) display hepatic metastases on initial staging in up to 20% of cases. The effectiveness of chemotherapy is generally evaluated by computed tomography (CT) imaging using standardized criteria (RECIST). However, RECIST is not always optimal, and other criteria have been shown to correlate with pathologic response and overall survival. The aim of this study was to evaluate the prognostic value of different CT measurement for response assessment after initiation of chemotherapy in patients with synchronous colorectal cancer liver metastases.

Methods: Fifty-five patients with CRC and synchronous hepatic metastases were evaluated retrospectively at 2 academic centers. Different size, volume, ratio and attenuation parameters were determined at baseline and after 3 cycles of chemotherapy. The prognostic value of baseline measurements and of the change between baseline and second measurements was analyzed using Kaplan-Meier estimates.

Results: Median time to progression was 279 days, median overall survival was 704 days. In this selective patient population, neither a significant prognostic value of initial baseline CT parameters nor a prognostic value of the change between the first and the second CT measurements was found.

Conclusion: Initial morphological response assessment using different CT measurements has no prognostic value concerning time to progression or overall survival in patients with synchronous colorectal liver metastases.

Figure 1

Parameters determined on baseline CT and second CT. Maximum diameter of the largest lesion in 1 plane (max1D) (mm) (a); product of the 2 maximum diameters of the largest lesion in 2 planes (max2D) (mm²) (b); product of the 3 maximum diameters of the largest lesion in 3 planes (max3D) (mm³) (c); sum of the maximum diameters (SLD) of the 2 largest lesions (RECIST 1.1 criteria) (mm) (d); volume of the largest lesion (mm³) (e); minimum, mean, and maximum Hounsfield units (HU_min, HU_mean, and HU_max) of the 3 largest lesions (f); tumor-to-liver-ratio (TTLR) of the 3 largest (TTLR_three) and of all lesions (TTLR_all) (%) (g).

Figure 2

Survival functions depending on baseline values of max1D (maximum diameter of the largest lesion in 1 plane). (a) OS: group 1/small lesions, n = 18; group 2/medium lesions, n = 19; group 3/large lesions, n = 18. (b) TTP: group 1/small lesions, n = 11; group 2/medium lesions, n = 10; group 3/large lesions, n = 10.

Figure 3

Survival functions depending on baseline values of TTLR_all (tumor-to-liver-ratio of all lesions). (a) OS: group 1/low ratio, n = 12; group 2/medium intermediate ratio, n = 18; group 3/high ratio lesions, n = 25. (b) TTP: group 1/low ratio, n = 5; group 2/intermediate ratio, n = 13; group 3/high ratio, n = 13.

Figure 4

Survival functions depending on the baseline values of HU_min (minimum Hounsfield units of the 3 largest lesions). (a) OS: group 1/low HU_min lesions, n = 26; group 2/intermediate HU_min lesions, n = 4; group 3/high HU_min lesions, n = 25. (b) TTP: group 1/low HU_min lesions, n = 24; group 2/intermediate HU_min lesions, n = 1; group 3/high HU_min lesions, n = 6.

Figure 5

Survival functions depending on trend values of max1D (maximum diameter of the largest lesion in 1 plane). (a) OS: group 1/regressive lesions, n = 20; group 2/stable lesions, n = 28; group 3/progressive lesions, n = 7. (b) TTP: group 1/regressive lesions, n = 12; group 2/stable lesions, n = 15; group 3/progressive lesions, n = 4.

Figure 6

Survival functions depending on trend values of SLD (sum of the longest diameters) of the 2 largest lesions (RECIST 1.1). (a) OS: group 1/partial response (PR), n = 23; group 2/stable disease (SD), n = 22; group 3/progressive disease (PD), n = 10. (b) TTP: group 1/partial response (PR), n = 13; group 2/stable disease (SD), n = 13; group 3/progressive disease (PD), n = 5.