The genetic landscape of fibroepithelial tumors, a distinct group of breast tumors, has been uncovered. The study identified the culprit genes behind the formation and progression of these tumors, potentially improving the diagnostic accuracy of breast cancer and enhancing clinical intervention for patients with this tumor type. The study’s findings were published in Nature Genetics (2015; doi:10.1038/ng.3409).

Fibroepithelial tumors are a distinct breast tumor group that includes two tumor types: fibroadenomas and phyllodes tumors. Fibroadenomas are the most common benign breast tumors in women of reproductive age, with estimates of fibroadenoma diagnoses to be in the millions worldwide every year.

Recently, the team, from the SingHealth Duke-NUS Academic Medical Centre, comprising scientists and clinicians from the National Cancer Centre Singapore (NCCS), Singapore General Hospital (SGH) and Duke-NUS Graduate Medical School, identified novel MED12 mutations in the majority of fibroadenomas. Now, they have charted the genetic landscape for fibroadenomas, as well as phyllodes tumors, which has both benign and cancerous forms, the latter accounting for approximately 2% of breast cancers in Singapore.

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“By shedding light on the genetic landscape of fibroepithelial breast tumors, we can delve deeper into how they are formed, their possible progression into cancer, and determine how to manage them,” said Professor Teh Bin Tean, MD, PhD, Deputy Director (Research), NCCS, a co-principal investigator (PI) of the study.

Currently, distinguishing fibroadenomas from phyllodes tumors can be challenging. The tumors can also progress from benign to malignant forms, and recur after surgical removal. A deeper understanding into their formation and progression is thus important for the accurate diagnosis and treatment of such tumors, and for breast cancer care.

The team studied 100 fibroepithelial tumors and uncovered the genes responsible for their formation and progression.

Understanding the genetic landscape of fibroepithelial breast tumors allows doctors to improve the diagnostic accuracy of breast tumor assessment.

“In pathology, we see challenging cases where fibroadenomas and phyllodes tumors are not clearly distinguishable. The discovery of their causative genes brings hope that we can eventually test for the presence of culprit genes to identify these breast tumor types accurately. Patients can then receive appropriate clinical intervention in a timely manner,” said Professor Tan Puay Hoon, MD, head and senior consultant, Department of Pathology, SGH and co-PI of the study.

Professor Steve Rozen, PhD, from Duke-NUS’ Cancer and Stem Cell Biology Programme and co-PI of the study further explained, “If gene mutations in a patient’s breast tumor suggest it may progress from a benign to cancerous form, doctors can then advise patients to have it completely surgically removed to prevent cancer occurrence.”

The findings also provide candidate therapeutic targets for fibroepithelial tumors, paving the way for alternative treatment options. Currently, there is no effective therapy for phyllodes tumors apart from surgery. This study opens the possibility of developing drugs targeting the tumors gene pathway, offering hope to treat or prevent recurrence.