BREAST CANCER INDEX

BREAST CANCER INDEX

Gilardi et al. comment about breast cancer subtypes. Immunohistochemical (IHC) determination of oestrogen and progesterone receptors (ER and PgR), the detection of overexpression and/or amplification of human epidermal growth factor receptor 2 (HER2) and the Ki67 labelling index have been defined as a convenient alternative to molecular subtyping and are considered a sufficient to guide therapeutic choices.

Basal-like tumours are often referred to as triple-negative breast cancer because most basallike tumours are negative for ER, PgR and HER2. This is true for about 75 % of these tumours, while the remaining 25 % include all the other molecular subtypes.

Humbert et al. found that baseline FDG uptake of primary tumours and its early response to neoadjuvant chemotherapy may vary according to the IHC subtype of the breast cancer. Pathological complete response (pCR) occurred more often in these two subtypes, rather than in luminal tumours, and the relative change in SUV was predictive of pCR only in HER2-positive tumours with an accuracy of 76 %.

18F-FDG is not the only radiopharmaceutical available to evaluate patients with breast cancer. Novel PET tracers already tested in humans, such as 18F-fluoroestradiol (FES, that binds to ER), 18F-FFNP (a progesterone analogue) and 68Ga-ABY-002 and 89Zr-trastuzumab (molecular imaging agents with high specificity and affinity for HER2), may provide additional useful information about breast cancer marker expression, tumour heterogeneity and responsiveness to therapy.

They concluded that, combined evaluation of a patient by PET/CT scanning with different tracers could permit the outlining of a portrait of breast cancer heterogeneity.

References:

Gilardi Laura, Colleoni Marco and Paganelli Giovanni . PET/CT and breast cancer subtypes. Eur J Nucl Med Mol Imaging (2013) 40:1301–1303

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