Regions of brain metastasis vary by breast cancer subtypes
Different breast cancer subtypes appear to show different spatial distributions of brain metastasis (BM), with luminal type and human epidermal growth factor receptor 2 (HER2)-positive breast cancers showing BM dominance in the occipital lobe and cerebellum, suggests a recent study.
Brain magnetic resonance (MR) images of 100 breast cancer patients with confirmed BM were retrospectively analysed. Distribution patterns of BM were compared among and within groups, which were defined by biological subtype of the primary tumour.
In the study sample, 24 patients had triple-negative primary breast cancers (mean age at diagnosis 46.45±10.88 years), 48 were HER2-positive (mean age at diagnosis 49.5±11.45 years) and 28 had luminal breast cancer (mean age at diagnosis 46.75±9.73 years).
While the mean number of BM per patient did not differ among the subtypes (5.04±6.37, 4.71±6.58 and 5.35±6.69), both triple negative (23.5±23.36 months) and HER2-positive (19±29.54 months) cancers had significantly shorter time to BM than luminal breast cancers (42±45.51 months; p<0.01).
In intergroup analysis, researchers found that BM from triple-negative breast cancers was more likely to occur in the limbic region, parietal lobe and frontal lobe (corrected p<0.05) compared to the other cancer subtypes.
In contrast, HER2-positive breast cancers were less likely to have BM in the frontal lobe and subcortical regions, while BM from luminal type breast cancers were less likely to happen in the cerebellum, subcortical region and occipital lobe compared with the other cancer subtypes (corrected p<0.05).