In this report, we experienced the patient who presented with synchronous locally advanced bilateral breast cancers with different tumor biology: the left breast cancer was hormone receptor (HR)-negative and HER2-positive, meanwhile the right breast cancer was HR-positive and HER2-negative status. We had planned NAC targeting to the left breast cancer which seemed more progressive disease, thus we administered FEC followed by wPac + T and as expected, those mass showed different mass reduction responses. Importantly, it is recently reported that the HR and HER2 status, breast cancer subtype, are involved with the mass reduction effect of NAC and pathological response. Furthermore, in term of patient’s prognosis, there is different significance of pCR depending on breast cancer subtype (Toi et al. 2008).
It is well known that HER2 overexpression has been associated with benefit from anthracycline-based chemotherapy (Gennari et al. 2008) and trastuzumab-containing chemotherapy, which is a monoclonal antibody targeting the extracellular domain of the HER2 protein (Hudis 2007). As regarding NAC, recent randomized trials present that anthracycline and trastuzumab containing chemotherapy could achieve higher pathological response rates (Gianni et al. 2010;Buzdar et al. 2007). Moreover, treatment response, especially pCR, has a possible surrogate marker of patients’ prognosis after NAC (Von Minckwitz et al. 2012). Taken together, in HER2 type breast cancer, the patients with pCR has a better prognosis than those of non-pCR. Supporting this evidence, even in our locally advanced case, the left tumor resulted in pCR and she has no recurrence for about six years after the start of the treatment.
In related to HR status and systemic therapy, accumulating evidence suggests that the effect of conventional chemotherapy is greater among HR-negative breast cancers (Berry et al. 2006). This is particular striking in the neoadjuvant setting; HR-negative breast cancer is more likely to achieve a pCR to NAC compared to those with HR-positive breast cancer (Ring et al. 2004). HR status is a strong predictive factor of pCR. However, it is really important that pathological response to NAC might not have prognostic significance in patients with HR-positive breast cancer (Von Minckwitz et al. 2012). It must be noted, no mass reduction doesn’t lead to no treatment effect, regarding to prevention of recurrence (Peto et al. 2012). Also in our case, the right mass showed little reduction with a lot of lymph node metastasis remaining. However, fortunately, she has no recurrence for five years after the completion of NAC, though it was more likely to have a recurrence even such a locally advanced and multiple lymph node metastasis.
These days it is common view that breast cancer treatment strategy based on the breast cancer subtypes, considering target therapy to tumor biology as predictive factor for breast cancer oncologist (Goldhirsch et al. 2011). However, at that time, it was largely unknown the meanings of pCR after NAC, and the value of surrogate marker of patients’ prognosis. This bilateral breast cancer case showed typical courses in current treatment strategy through the NAC based on the tumor biology, and a long time follow up showed the meaning of pathological response to NAC based on tumor subtype, even in locally advanced case. This could be the informative experience to understand the relation of treatment response and tumor biology and patient’s prognosis for the various oncology subspecialists.