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Keywords:
Breast, Oncology, MR, Diagnostic procedure, Cancer
Authors:
M. Nadrljanski, R. Maksimovic, V. Plesinac-Karapandzic, M. Nikitovic, Z. C. Milosevich; Belgrade/RS
DOI:
10.1594/ecr2015/B-0016
Purpose
The purpose of this paper was to assess tumor response after the 2nd cycle of neaodjuvant chemotherapy (NACT) according to:
1.) Standardized assessment tool – RECIST,
based on purely morphologic changes – tumor diameter change,
with the response assessment categorization assigned according to the percentage of the change in the sum of the target diameters [1],
2.) Apparent diffusion coefficient (ADC),
based on the diffusion-weighted imaging (DWI),
i.e.,
the change in ADC value initially and upon the completion of the 2nd cycle of the standardized NACT regimen (anthracycline based) [2-6].
NACT is the standardized therapeutic approach for pre-surgical treatment of the locally advanced breast cancer (LABC) and the initially operable breast cancer – aiming to downstage the large tumors in order to improve surgical options: breast-conserving surgery,
taking into account the fact that the pathological complete response (pCR) is defined as the specific surrogate endpoint for survival outcome [4-8].
The “early tumor response” defined on breast DCE-MRI after the 2nd cycle of NACT based on morphologic (RECIST) and functional (ADC) criteria may contribute to the identification of the responders to the standardized anthracycline-based NACT [6-8].
According to RECIST,
the complete response (CR) considers the disappearance of all target lesions,
while the partial response (PR) represents the decrease of at least 30% in the sum of diameters of target lesions compared to the initial values [1].
The change in ADC value,
as the measure of tumor response to NACT has not been standardized,
neither from the technical point of view (e.g.
selection of the gradients – b-values…),
nor from the clinically relevant predefined cut-off values based on the large trials and set as the standard through the relevant guidelines.
Certain cut-off values were however suggested,
based on the limited number of trials: the increase in ADC value of at least 14% after the 1st cycle and/or 27% after 2nd cycle of NACT in responders (R) [8].