New breast cancer classification based on epigenetics.
Researchers from Institut d’Investigació Biomèdica de Bellvitge (IDIBELL) have established the epigenetic patterns of breast cancer and also its clinical consequences. The opensource study is published in the journal Molecular Oncology.
Statistics from The Breast Cancer Research Foundation state that nearly 1.7 million new breast cancer cases were diagnosed in 2012. Breast cancer is the second most common cancer in women and men worldwide. In 2012, it represented about 12 percent of all new cancer cases and 25 percent of all cancers in women. Breast cancer is the most frequently diagnosed cancer among women in 140 of 184 countries worldwide.
Globally, breast cancer now represents one in four of all cancers in women. Progress in prevention and early detection, and the use of chemotherapy after surgery (adjuvant chemotherapy), have achieved significantly increase survival in this disease in the last ten years, but much remains to be done.
The identification of patients with high-risk breast cancer is key to knowing whether a patient will require only the removal of the tumour by surgery or whether if they will need additional chemotherapy to make sure the removal of breast cancer cells. Currently, known genetic mutations and expression patterns are determined, but the puzzle of the genetics of the disease remains a large unfinished part.
To address this the researchers analyzed epigenetic alterations, namely the chemical signal called DNA methylation in 500 breast tumours and have compared the patterns obtained with the clinical behaviour of these cancers.
The team note that there are two subgroups of breast tumours by epigenome; one which they have named Epi-Basal, characterized by loss of epigenetic marks causing breakage of chromosomes and the other that the researchers have called Epi-Luminal B, that presents epigenetic inactivation of genes that should protect humans from cancer and the altered cells that can no longer do it.
The researchers highlight that the subtype Epi-Luminal B behaves particularly aggressive form, and is associated with reduced survival of patients. They would therefore recommend that with this class of tumour the medical team avoid surgery and instead administer adjuvant chemotherapy and in those tumours with a more ‘benign’ epigenetic pattern; surgery alone may be curative, thus avoiding the side effects of chemotherapy.