ESMO 2019 Congress | OncologyPRO

Abstract 5792

Background

Early predicting the pathologic complete response (pCR) after neoadjuvant chemotherapy in patients with locally advanced breast cancer (LABC) is closely associated with clinical outcomes. However, conventional metabolic parameters using baseline ¹⁸F-FDG PET/CT have failed to accurately predict the pCR. Breast cancer stem cells (CSCs) are known for their established role in chemoresistance. We designed a new PET parameter for CSC metabolism (MTVcsc) from pretreatment ¹⁸F-FDG PET/CT by using distinctive glucose metabolism between CSCs and differentiated cancer cells, and aimed to evaluate the prognostic value of the MTVcsc.

Methods

A total of 71 patients with LABC who underwent initial ¹⁸F-FDG PET/CT before NAC were included in this study. The SUV values of single voxels within the primary tumor were clustered by performing k-means clustering using R version 3.5.3 and MTVcsc was derived by calculating the volume of the most glycolytic cluster. The predictive values of the MTVcsc, as well as clinicopathologic and conventional metabolic parameters (SUVmax, MTV, TLG) for pCR, were analyzed by multivariable logistic regression.

Results

Seventeen patients were excluded from the final analysis due to small tumor size (< 64 voxels). The lower MTVcsc and non-luminal subtypes were significantly associated with achieving pCR following NAC (Table). The MTVcsc outperformed the conventional PET parameters in predicting pCR. Table Univariable and multivariable logistic regression model of clinicopathologic and metabolic parameters for predicting pathologic complete response.Table: 301P

Parameters	Univariable analysis	Multivariable analysis
OR	95% CI	P value	OR	95% CI	P value
Ki-67
Low, < 20% High, ≥ 20%	1.00
5.57	1.06-29.27	0.043
Molecular subtype
Luminal A and B HER2 positive Triple negative	1.00			1.00
11.46	2.07-63.36	0.005	13.7	1.75-107.36	0.013
6.55	1.05-40.67	0.044	17.42	1.41-215.04	0.026
Metabolic parameters
SUVmax Metabolic tumor volume (MTV) Total lesion glycolysis (TLG) MTVcsc	0.98	0.83-1.16	0.814
0.98	0.94-1.02	0.281
0.99	0.98-1.00	0.231
0.29	0.10-0.89	0.031	0.21	0.05-0.82	0.025

Conclusions

MTVcsc, a novel PET parameter for CSC metabolism, provides predictive value for pCR. By further stratifying LABC patients with a combination of MTVcsc and molecular subtype at initial staging workup, achieving pCR after NAC can be early predicted more accurately.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.

Resources from the same session

29 Sep 2019