Correlation of clinico-pathological outcomes with changes in IHC4 status after neo-adjuvant chemotherapy (NACT) for locally advanced breast cancers: Do pre NACT ER/PR status act as better prognosticators?

Animesh Saha1,Sanjoy Chatterjee1,Sanjit Agarwal1,Rosina Ahmed1,Indu Arun1,Sonali Nayak1,Mayur Parihar1,Subir Sinha1

1Tata Medical Center, Kolkata, West bengal, India

Presenting date: Tuesday 3 November

Background

Differential expression of  4 immumohistochemical markers ( IHC-4) i.e, oestrogen receptor (ER), progesterone receptor (PR), Her-2  receptor and  Ki-67   in breast cancer is used as surrogate to molecular classification. The correlation of   changes in IHC-4 following neoadjuvant chemotherapy (NACT) , to tumour pathological response rates (pCR) and  disease relapse rates could lead to better understanding of tumour behaviour.

Method

Pre and post NACT IHC 4 status was analysed in 156  breast cancer patients. Response to chemotherapy was reported as per CAP recommendations 2009. Associations between IHC-4  before and after NACT were evaluated by using the McNemar test for ER, PR, HER-2  and a paired Student t-test for the Ki-67. Associations between the pCR to other categorical variables were assessed by using the chi-square tests or Fisher exact tests. Associations between pCR and the Ki-67 index were performed using the independent Stu­dent t-test. Kaplan-Myer plots were analysed to obtain relapse free survival (RFS).

Results

The median age was 48years.  25.3 % patients had pCR . Grade 3 tumours had a higher pCR (27.4%).  ER and PR both positive tumours had the lowest (14.3%) pCR  compared to tumours with both ER and PR negative (29% ) or  those with either ER or PR positive (38.6%). PR positivity was significantly associated with less likelihood of  pCR  (15% vs 34%).  The pCR rate was lowest for LA subtype  (13.68%) compared to 24.36%, 26.31%, 33.33% for LB, HE and TN subtypes respectively.  There were significant reduction in expression of ER receptors  and   Ki-67 index   post NACT.   RFS of patients in whom the hormonal status changed from positive to negative was better compared to  those who changed from negative to positive.

Conclusion

Changes in IHC 4 occur post NACT. pCR rates are lower in PR positive tumours and pre, not post, NACT HR status seemed to prognosticate RFS better.