Background

Oestrogen receptor (ER) and progesterone receptor (PgR) positive status is associated with good prognosis in breast cancer. Additionally, both these molecular markers have been suggested as independent predictors of response to hormonal therapy. We examined primary breast cancers using array comparative genomic hybridisation (aCGH) to identify cytogenetic abnormalities associated with ER and PgR status and then assessed the prognostic significance of our aCGH findings.

Method

Formalin fixed paraffin embedded tissue sections from 81 primary breast cancers with available clinical and histopathological data including ER and PgR status were studied using aCGH. The data was statistically analysed using backward stepwise Binary Logistic Regression (BLR) to find independent associations between ER/PgR status and the most frequent cytogenetic abnormalities.

Results

Gain of the 16p11.2 region independently associated with ER positive (P<0.001) and PgR positive (P=0.003) status. This region is also involved in the unbalanced whole arm der(1;16)translocation that is known to be associated with ER positive status and good outcome in breast cancer.  Additionally, we found that loss of the 10q25.1 region associates with ER negative (P<0.001) and PgR negative (P<0.001) status.

Conclusion

Independent association of the 16p11.2 region gain with ER and PgR positive status indicates a good prognosis of this abnormality in primary breast cancer. Further, the loss of 10q25.1 region may be a potential marker of poor prognosis due to its association with ER and PgR negative status.