Immunohistochemistry Heterogeneity in Reported Breast Cancer Demographics From India: Triple-Negative Breast Cancer Rates Could Be Lower Than Suggested in Pooled Meta-Analysis

The meta-analysis of breast cancer demographics in Indian patients by Sandhu et al highlights significant variability in estrogen receptor (ER)/ progesterone receptor (PR)/human epidermal growth factor receptor 2 (HER2) status and presenting age reported by various authors and then pools the data to ascertain the rate of triplenegative breast cancer (TNBC) to be around 31%. We feel that such a report may overlook a fewimportant issues,whichwewould like tooutline. Theauthors rightly highlight that local, environmental, and physical factors may contribute to the heterogeneity but have not explored some of them. Of the studies included, only four centers reported an average of over 20 patients per month. Small series, such as that by Akhtar et al, are likely to be unrepresentative of the regional population and could present a selection bias. However, the referral patterns for high-volume tertiary care centersmayalsocontributesignificantly to theselection bias,which is reflected in the younger age in someof theseseries. Inaddition, somestudies, suchas those by Nandi et al and Ambroise et al, reported immunohistochemistry (IHC)onlyonpatients receiving curative therapy, in contrast to others, who reported on all patients who presented to the hospital. This could also contribute to the heterogeneity reported.