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The power of choice

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According to the Canadian Women’s Health Network, about 60,000 cases of ductal carcinoma in situ (DCIS) are diagnosed each year and many patients receive radiation therapy in addition to breast-conserving surgery. What Dr. Eileen Rakovitch, a scientist in the Odette Cancer Research Program at Sunnybrook Research Institute, and her colleagues have found, however, is that radiation therapy may not be required for all women.

Rakovitch and her colleagues set out to validate a test to identify the women in need of radiation therapy after surgery, and determine which patients are at low risk of recurrence and in a position to bypass the additional treatment. To do so, they used the Oncotype DX DCIS Score, a test that evaluates the expression of 12 genes in breast tumours to reveal the risk of recurrence. The higher the score, the greater the chance of the cancer’s return; the lower the score, the lesser the likelihood of the cancer’s recurrence. They looked at 1,260 women diagnosed with DCIS in Ontario who between 1994 and 2003 either had breast-conserving surgery alone, or surgery plus radiotherapy. Samples of their tumours were tested to produce a score.

The results showed 
low-risk women treated by breast-conserving surgery alone had a local recurrence risk of 10.6% at 10 years and only a small benefit from radiation therapy. Alternatively, women with higher scores had a local recurrence risk of 25.4% after surgery and experienced a greater benefit from radiotherapy.

If validated, the findings would arm doctors with greater knowledge and equip women diagnosed with DCIS to select a treatment approach specific to their needs. With such a test, patients would no longer be reliant on a generic estimate, but instead have the information required to elect an individualized plan.