Fibroadenoma is one of the most common breast tumors diagnosed in women under the age of 30 years. Fibroadenoma is commonly found when testing for breast cancer, and clinicians are challenged with how to distinguish fibroadenoma from breast cancer.
Researchers from National Cancer Centre Singapore, Duke-NUS Graduate Medical School Singapore, and Singapore General Hospital carried out DNA sequencing on 90 fibroadenoma samples from patients from Singapore, in the hope that genetic testing would be diagnostically useful. In 59% of samples, a disruption of the MED12 was present, with 77% of the mutations being found in codon 44.
One of the lead authors of the study, Tan Puay Hoon, commented that, “It is amazing that these common breast tumors can be caused by such a precise disruption in a single gene. Our findings show that even common diseases can have a very exact genetic basis. Importantly, now that we know the cause of fibroadenoma, this research can have many potential applications.”
Tan further explained the future potential application of this discovery: “Measuring the MED12 gene in breast lumps may help clinicians to distinguish fibroadenomas from other types of breast cancer. Drugs targeting the MED12 pathway may also be useful in patients with multiple and recurrent fibroadenomas as this could help patients avoid surgery and relieve anxiety”. The technique the researchers used, laser capture microdissection, enabled them to observe that the MED12 mutations were found in the stromal cells of the breast tumors, while in breast cancer tumors the mutations are found in the epithelial cells of the tumors. Targeting the stromal cells could be a new avenue in which to explore.
Interestingly, this reflects findings seen in uterine fibroids, benign tumors that can arise in the uterus, where MED12 mutations have also observed. Tan said, “Combined with our data, the fact that MED12 mutations are shared, highly frequent, and specific to fibroadenomas and uterine fibroids strongly attests to a role for abnormal responses to female hormones in the birth of these tumors.”
The researchers are planning to extend their research in MED12 to identify its role in other breast tumors.
Source: Lim WK, Ong CK, Tan J et al. Exome sequencing identifies highly recurrent MED12 somatic mutations in breast fibroadenoma. Nat. Genet. 46(8), 877–880 (2014).