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Journal of the National Cancer Institute

July 06, 2005

Women with a relatively rare and aggressive form of breast cancer tend to be younger, have larger tumors, and have a poorer survival rate compared with women with the most common forms of the disease, reports a new study in the July 6 issue of the Journal of the National Cancer Institute.

Inflammatory breast carcinoma (IBC) is a relatively rare and understudied type of breast cancer characterized by redness, warmth, and swelling, often without an underlying palpable mass. However, case definitions for the disease vary, so estimates for how often it occurs have ranged widely from less than 1% to 10% of breast cancer cases.

To learn more about the incidence and characteristics of IBC, Kenneth W. Hance, Ph.D., M.P.H., of the National Cancer Institute (NCI) in Bethesda, Md., and colleagues studied data from the Surveillance, Epidemiology, and End Results (SEER) program on more than 180,000 breast cancer cases diagnosed between 1988-2000. SEER is a large database managed by the NCI that collects data from cancer registries across the country that cover about 26% of the U.S. population.

The authors calculated that IBC comprised about 2% of all breast cancer cases and that women were diagnosed with IBC at an average age of 58.8 years-about 3 to 7 years younger than the average age of women diagnosed with other forms of breast cancer. In addition, patients with IBC had a poorer survival rate, with a median survival of 2.9 years after diagnosis compared with 6.4 to 10 years for other types of breast cancer. Black patients with IBC had a poorer survival rate than white patients. On average, IBC tumors tended to be larger than those in other forms of breast cancer.

They found that the number of cases of IBC appears to be rising; the incidence rate increased between 1988 and 1999 from 2.0 cases per 100,000 women to 2.5 per 100,000. (By comparison, the incidence of more common forms of breast cancer decreased from 108 cases per 100,000 women to 101 per 100,000 during the same time period.) Black women had a higher incidence rate of IBC-3.1 cases per 100,000 women-compared with white women (2.2 cases per 100,000 women). The authors cite heightened clinical awareness and changing patterns of risk factor exposure as possible explanations for the rise in reported cases.

Although they report that their study helps create a comprehensive definition for IBC in the SEER database, the authors state that finding a molecular determinant and genetic profile for the disease is still needed to "facilitate our understanding of the etiology of this disease, and to identify IBC subtypes that may possess common therapeutic responses and clinical outcomes," they write.

Journal of the National Cancer Institute