Significance of re-biopsy for recurrent breast cancer in the immune tumour microenvironment

Immune responses in a tumour microenvironment can be evaluated by analysing tumour-infiltrating lymphocyte (TIL) density; this has been verified in the clinical setting. Although there are many reports on TIL density in primary tumours, little is known about its density in recurrent tumours.

Of 300 patients treated with neoadjuvant chemotherapy during the study period, 29 were considered for evaluation of TIL density in primary and recurrent tumours. We performed a retrospective analysis of the association between TIL density and prognosis.

TIL density was significantly lower in recurrent tumours than in primary tumours (P = 0.007). There was no correlation between post-recurrence survival and TIL density in core-needle biopsy specimens obtained from primary tumours (P = 0.837). However, patients with high TIL density in recurrent tumours had significantly better post-recurrence survival than did the corresponding group with low TIL density (P = 0.041). Multivariate analysis revealed that high TIL density contributed significantly towards improving post-recurrence survival in all patients (P = 0.035; hazard ratio, 0.167).

In recurrent breast cancer, a decrease in TILs density was observed as compared to the primary tumour, and this affects the poor prognosis after relapse.