Tumor growth kinetics versus RECIST to assess response to locoregional therapy in breast cancer liver metastases.
OBJECTIVE
The aim of our study was to evaluate changes in growth kinetics of breast cancer liver metastasis in response to locoregional therapy and compare them to Response Evaluation Criteria in Solid Tumors (RECIST).


METHODS
This Health Insurance Portability and Accountability Act-compliant retrospective study was Institutional Review Board approved. Thirty-four chemorefractory breast cancer liver metastases from 21 patients treated with yttrium-90 ((90)Y) were evaluated. Pre- and posttreatment computed tomography (CT) scans were used to calculate tumor growth kinetics. The growth parameter analyzed was reciprocal of doubling time (RDT). RDT range for stable disease (SD) was defined by the measurement error rate. A negative RDT below the SD range defined response and was categorized as either partial response (PR) or complete response, whereas a positive RDT value above the SD range indicated progressive disease (PD). Comparison was made to tumor response classification according to percentage change in the lesion's maximal diameter per RECIST. Lin's concordance correlation coefficient, Bland-Altman plot, Wilcoxon signed rank test, and Student t test were used for analysis. Significance was set at 0.05.


RESULTS
RDT range for SD ranged from -0.46 to +2.17. Six lesions with PR based on RECIST showed PR based on their volumetric growth rate (mean RDT of -17.3 ± 2.6). Similarly, one lesion with PD according to RECIST was categorized as PD based on its growth kinetics (RDT of 10.2). However, 14 (51.85%) lesions classified as SD by RECIST had PR according to growth kinetics (mean RDT of -7.8), six (22.22%) lesions were categorized as SD (mean RDT of 0.8), whereas seven (25.93%) lesions showed PD (mean RDT of 4.5). Growth kinetic parameters were significantly different for lesions with PR when compared to lesions with PD (P < .0001).


CONCLUSIONS
In patients with breast cancer liver metastases undergoing locoregional therapy, RECIST categorization may not be an accurate reflection of treatment response.
Department of Radiology, Northwestern Memorial Hospital, Northwestern University-Feinberg School of Medicine, 676 North Saint Clair Street, Suite 800, Chicago, IL 60611.
Adeel R
AR
Seyal
Department of Radiology, Northwestern Memorial Hospital, Northwestern University-Feinberg School of Medicine, 676 North Saint Clair Street, Suite 800, Chicago, IL 60611.
Keyur
K
Parekh
Department of Radiology, Northwestern Memorial Hospital, Northwestern University-Feinberg School of Medicine, 676 North Saint Clair Street, Suite 800, Chicago, IL 60611.
Yuri S
YS
Velichko
Department of Radiology, Northwestern Memorial Hospital, Northwestern University-Feinberg School of Medicine, 676 North Saint Clair Street, Suite 800, Chicago, IL 60611.
Riad
R
Salem
Department of Radiology, Northwestern Memorial Hospital, Northwestern University-Feinberg School of Medicine, 676 North Saint Clair Street, Suite 800, Chicago, IL 60611. Electronic address: v-yaghmai@northwestern.edu.
Vahid
V
Yaghmai
D000328:Adult; D000368:Aged; D000465:Algorithms; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007700:Kinetics; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary*; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D011379:Prognosis; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D066066:Response Evaluation Criteria in Solid Tumors; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D016896:Treatment Outcome; D047368:Tumor Burden
Breast neoplasm; RECIST; Yttrium-90; computed tomography; liver metastasis