Inflammatory breast carcinoma (IBC) represents a rare but very aggressive subtype of breast cancer. It is a clinicopathologic entity that is characterized by distinct skin changes suggestive of infection or inflammation, usually of fairly abrupt onset and rapid progression. The breast often appears red, swollen, and inflamed, hence the term inflammatory breast cancer. Since IBC has historically been a clinical diagnosis, its true incidence has been hard to quantify based in large part on a lack of consensus about a case definition for IBC. Acknowledging variations in the case definitions for IBC in population-based registries, it is estimated that IBC accounts for almost 2% of all breast cancer cases here in the United States (1).
Because of its unique appearance, IBC has often been confused with locally advanced breast cancer (LABC). However, emerging epidemiologic and molecular evidence indicates that IBC is not a part of the spectrum of LABC, but is in fact a separate entity (2). Furthermore, a distinction must be made between primary IBC, which is the simultaneous development of inflammatory skin changes and carcinoma in a previously healthy breast, and secondary IBC, which is the development of inflammatory changes in a breast known to have had a prior malignancy; the outcomes from these two diseases are quite different. Patients with primary IBC usually have a relatively short duration of symptoms prior to diagnosis, usually less than 3 months. Patients that have had symptoms for more than 3 months are a more heterogeneous group and include patients with previous non-IBC that develop a new primary tumor or recurrence with clinical characteristics of IBC.
Worldwide, the incidence of IBC appears to be higher than in the United States, ranging from 2.1% in Turkey to as high as 50% in Tunisia (3). In fact, much of the information about IBC was initially derived from studies in Tunisia where about half of the breast cancer cases were attributed to IBC (4). More recent and updated data from Tunisia and other North African Countries now suggest a lower incidence using the criteria of the American Joint Commission for Cancer (AJCC) (5). Data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program demonstrate that while there has been a steady decline in non-IBC in general in the United States, the incidence of IBC has been on the rise over the last three decades. From 1973 to 2002, IBC has increased at an annual rate ranging from 1.23 to 4.35% per year, depending on the specific database analyzed and the case definition (1,3,6).
IBC is an aggressive and usually lethal form of breast cancer. Women diagnosed with IBC have statistically significantly poorer survival than women with either LABC or non-T4 breast cancer (p < 0.001), with a median overall survival (OS) ...