Inflammatory breast cancer (IBC) is diagnosed on the basis of signs of rapid progression, such as localized or generalized breast induration, redness and edema [1
]. IBC accounts for less than 5% of all diagnosed breast cancers [2
IBC is the most lethal form of primary breast cancer [2
]. Surgery and/or radiation therapy offers a 5-year survival rate of less than 15% [1
]. The current consensus treatment is first-line chemotherapy with an anthracycline-based regimen, possibly combined with a taxane, followed by mastectomy and axillary lymph node dissection for responders, locoregional radiotherapy and, when appropriate, hormone therapy [3
]. The benefits of dose-intensive therapy and bone marrow transplantation are not clearly established in this setting [5
]. Maintenance adjuvant chemotherapy and new therapeutic approaches are under study. Despite multimodality treatments, the prognosis remains poor, with a 3-year survival rate of only about 40%, compared with 85% among patients with non-IBC [2
]. These survival data have hardly improved in the past 5 years [3
The main issue in IBC is to identify the specific pattern of genetic changes accounting for this particular phenotype and aggressiveness, so that we can develop more effective targeted treatments. Little is known of these biological and molecular mechanisms, for several reasons. First, IBC is rare. Second, the small size of diagnostic samples may have hindered past molecular studies. Third, because of their similar treatment, IBC is rarely studied separately from other forms of locally advanced breast cancer (LABC), despite differences in age-specific incidence rates, clinical presentation, histology, hormone receptor status and, finally, prognosis [8
]. The molecular mechanisms underlying these distinct clinicopathological entities are likely to differ, and should thus be studied comparatively.
It is highly probable that the identification of significant molecular changes in IBC would help with diagnosis, with treatment response prediction, and with the development of new therapeutic targets. As about one-third of patients are disease-free 10 years after treatment, it would be useful to be able to identify the two-thirds of patients requiring intensified, prolonged, or new treatments. Most of the prognostic parameters used in non-IBC are unfortunately not relevant to IBC. The two main prognostic factors in early breast cancer (stages I and II) are the number of involved axillary nodes and the tumor size, but precise tumor measurement is often impossible at IBC diagnosis and most patients have axillary lymph node involvement.
The present review will focus on clinicopathological and biological knowledge of IBC.