High Proportion of Inflammatory Breast Cancer in the Population-Based Cancer Registry of Gharbiah, Egypt

Abstract

To the Editor: Inflammatory breast cancer (IBC), the most lethal form of breast cancer, constitutes 1‐2% of all breast cancers in the United States (1). Breast cancer comprises 352% of women’s cancers in the Gharbiah cancer registry (GCR) of Egypt (2). Hospital-based studies from the National Cancer Institute of Cairo University (NCI-Cairo) in Egypt suggested that IBC accounts for 10% of breast cancers (3). However, these estimates lacked confirmation from populationbased studies. To remedy this deficit, we performed this study to evaluate the frequency and features of IBC in GCR. Our initial review of GCR data between 1999 and 2003 showed that IBC did not exist despite the clinical experience with frequent cases of IBC at the GCR and the 10% relative frequency of the disease at NCICairo. A multi-disciplinary group of physicians in Egypt and the United States, who were experienced in the diagnosis and management of IBC, collaboratively developed an 84-item checklist of symptoms, signs, and clinical characteristic suggestive of IBC to facilitate and standardize abstraction of information from medical records. IBC cases were identified using the simplified clinical definition of Merajver and Sabel (4) that used erythema, edema, and peau d’orange as the three main clinical features of IBC. Subsequently, cases were grouped as follows: most-likely IBC exhibited all three features, possible IBC cases had any two of the three symptoms or had peau d’orange only, and non-IBC cases had edema only, erythema only, or had none of these three clinical features. IBC status was based on clinical criteria for IBC diagnosis (erythema, edema, and peau d’orange). The checklist was applied to all cases that had at least one of the three defining features of IBC and missing data was denoted. The study population had 659 cases, comprising four with most-likely IBC, 69 with possible IBC, and 586 who were non-IBC. IBC proportion was calculated according to two different definitions. Under the most stringent definition, most-likely IBC cases were considered as IBC, the proportion of IBC was 0.6%. Under a definition that both most-likely IBC cases and possible IBC cases were considered as IBC, the IBC proportion was 11.1%. There was no difference in age, parity, menopausal status, concurrent lactation, or family history between the IBC versus non-IBC groups. Warmth, diffuse enlargement, and nipple retraction were significantly higher among the IBC group compared with the non-IBC group (5.5% versus 0.2% with warmth, p < 0.01; 8.2% versus 0.7% with diffuse enlargement, p < 0.01; and 60.9% versus 8.2% with nipple retraction, p < 0.01, among IBC versus non-IBC groups, respectively). There were no significant differences between the two groups in bruising, palpable mass, or ulceration. The IBC group had 12.5% tumor emboli compared with 3.6% among the non-IBC group (p = 0.02). More patients (42.5%) in the IBC group received neo-adjuvant chemotherapy compared with 15.4% in the non-IBC group (p < 0.01). While 81.9% of the non-IBC group received surgical resection or radiotherapy (73.4%), this proportion was significantly higher than patients receiving resection or radiotherapy among the IBC group (53.5% and 51.9%, both p < 0.01). There was no significant difference between the IBC versus non-IBC groups in tumor grade, angiolymphatic invasion, or adjuvant chemotherapy. IBC cases had higher rate of metastasis (41.7%) compared with 27.8% for the non-IBC group (p = 0.10). Hormone receptors were higher in the IBC group than the non-IBC group (36.4% versus 16.7%, p < 0.01 for ER; 58.3% versus 36.2%, p = 0.04 for PR). After adjusting for warmth and systemic symptoms, nipple retraction was independently and significantly predictive of IBC (OR = 18.8, 95% CI: 9.6‐37.7). For the first time, this population-based study confirmed what hospital-based and anecdotal reports sug