Pathologic characteristics of breast cancer with special emphasis on prevalence of triple-negative breast cancer from Kenya: A 4-year experience.

Document Type



Pathology (East Africa)


Background: Previous sub classification of breast cancer in Kenya has been fraught by small sample size, non uniform staining methodology and lack of independent review. Triple Negative Breast Cancer (TNBC) is a “special interest” cancer since it represents a significant proportion of breast cancer patients and is associated with a poorer prognosis. We aimed to determine the estrogen receptor (ER), progesterone receptor (PR) and Her2/neu receptor characteristics of breast cancers and the prevalence of TNBC diagnosed at Aga Khan University Hospital, Nairobi (AKUHN) between 2007 to date.

Methods: Slides and blocks of archived invasive breast cancers diagnosed at AKUHN were identified, retrieved and reviewed by two independent pathologists. Histological type, grade and pathological stage were documented. Representative sections from available blocks were stained for ER, PR, Her2 with appropriate internal controls. Scores for ER/PR were interpreted based on the ALLRED system, Her2 /neu scoring followed CAP guidelines. The initial 111 cases were validated and confirmed at Sunnybrook Health Sciences Centre, Toronto.

Results: 456 cases of invasive breast cancers were diagnosed at AKUHN during the study period. 91% of cases were invasive ductal carcinomas (NOS).The rest were special types. 37% of the tumors were grade 3 and 63% were grade 2. Blocks for 318 of 456 cases were available for receptor analysis. 54% were ER and/or PR positive, with 52% of these in women < 50 yrs. 86% of the ER and/or PR positive tumors were grade 2. Only 12% were Her2/neu positive. Of the 318 cases studied, 111 (32%) were identified as TNBC. Median age was 53 yrs. 88% were grade 3.

Conclusions: Invasive ductal carcinoma (NOS) was the most common breast cancer in our study. Nearly half of our cases were ER and/or PR positive and a third were TNBC. Both occurred predominantly in women less than 50 yrs. This represents the largest validated pathologic sub classification of breast cancer from a tertiary academic hospital in Kenya. Expansion of this study to encompass all breast cancers diagnosed in Kenya is underway.

Publication (Name of Journal)

Journal of Clinical Oncology