Abstract

Currently, approximately 50% of all breast cancer patients are cured by loco regional therapy. Without adjuvant systemic therapy, 50% of patients will develop metastatic disease and ultimately die of the disease. Adjuvant chemotherapy cures around 10% of breast cancer patients, while adjuvant hormonal therapy cures about 15% of patients. This means that still roughly 25% of breast cancer patients will die of the disease, despite optimal breast cancer treatment.

Since it is very difficult to identify those patients that are already cured by loco regional treatment, and since under treatment is considered worse than overtreatment, about 90% of all breast cancer patients do receive some form of adjuvant systemic therapy. Clearly, this means that roughly 40% of patients receive adjuvant systemic therapy unnecessarily, with all its toxicities. In order to reduce overtreatment, prognostic factors are needed, to identify those patients who should be spared unnecessary adjuvant systemic therapy. One promising prognostic test is the 70-gene prognosis signature (MammaPrint®), which will be discussed in the seminar.

For the patients who do need adjuvant systemic therapy in order to be cured, it is crucial to choose the right systemic therapy. The only established predictive markers that can guide breast cancer therapy today are the oestrogen receptor status and the HER2 status. If used only in patients who would die without adjuvant systemic therapy, the number needed to treat to save one life is two to three. This means that of the patients who would die without adjuvant systemic therapy, still around 50% of these patients will die of the disease, despite systemic therapy. Additional predictive factors are needed to choose the drug that targets the Achilles heel of the tumour cells. In this seminar promising predictive factors for identifying patients who will benefit from intensified carboplatin-based chemotherapy and for identifying patients who are tamoxifen-resistant will be discussed.

Ultimately, the use of additional prognostic and predictive factors in breast cancer diagnosis and treatment will reduce overtreatment and improve survival.

Further reading

Beelen K, Zwart W, Linn SC. Can predictive biomarkers in breast cancer guide adjuvant endocrine therapy? Nat Rev Clin Oncol, in press. doi: 10.1038/nrclinonc.2012.121

Vollebergh MA, Jonkers J, Linn SC. Genomic instability in breast and ovarian cancers: translation into clinical predictive biomarkers. Cell Mol Life Sci, 69:223-45, 2012. doi: 10.1007/s00018-011-0809-0.

Bueno-de-Mesquita JM, van Harten WH, Retel VP, et al. Use of 70-gene signature to predict prognosis of patients with node-negative breast cancer: a prospective community-based feasibility study (RASTER). Lancet Oncol, 8: 1079-1087, 2007.

Support for this Seminar is provided by EISAI