Understanding Oncotype DX & Recurrence Scores

Tests such as Oncotype DX and MammaPrint are run on your tumor tissue. Not your blood, and not your inherited DNA. They measure how active certain genes are inside the cancer cells that were already removed. Oncotype DX reads 21 genes and reports a Recurrence Score from 0 to 100. MammaPrint reads 70 genes and reports one of two results, low risk or high risk. Both are used mainly in hormone receptor-positive, HER2-negative early breast cancer.

These tests are not a scan. Nothing about the score tells you whether cancer is in your body now.

This is the part people most often get wrong. The score does estimate the chance of the cancer coming back over roughly the next decade with hormone therapy alone. But its practical job is different. It estimates whether adding chemotherapy would really change that chance for you.

Those are two separate questions. Two people can have similar recurrence risk and very different expected chemotherapy benefit. Benefit depends on how the tumor's biology responds to chemotherapy, not just on how likely the cancer is to return. A tumor can be fairly likely to recur and still gain very little from chemotherapy. That is why a score can be reassuring about how much treatment you need, without claiming your risk is zero.

TAILORx enrolled 10,273 women with hormone receptor-positive, HER2-negative, node-negative breast cancer. Scores of 0 to 10 were treated as low risk, 11 to 25 as intermediate, and 26 or above as high. Practice had been genuinely uncertain for the intermediate group. So that group was randomly assigned to hormone therapy alone, or to hormone therapy plus chemotherapy.

Adding chemotherapy made no meaningful difference for most of them. Five-year invasive disease-free survival was 92.8% with hormone therapy alone and 93.1% with chemotherapy added. That gap is too small to count as real. There was one exception: women aged 50 or younger with scores in the upper part of that band, 16 to 25. A small benefit showed up there. It may have come from chemotherapy shutting down ovarian function, rather than from a direct effect on cancer cells.

Put together, the results showed that roughly 70% of women with this type of breast cancer could safely skip chemotherapy. That means anyone with a score of 0 to 10, women over 50 with scores of 11 to 25, and women 50 or under with scores of 11 to 15.

MINDACT tested the 70-gene signature in 6,693 patients. Its central group was women judged high risk by traditional clinical features, but low risk by the genomic test. At long-term follow-up, chemotherapy improved eight-year distant metastasis-free survival by about 2.6 percentage points overall. But the pattern split sharply by age. Women over 50 saw almost nothing, around 0.2 points. Women under 50 saw closer to 5 points. For postmenopausal women in that group, the conclusion was that chemotherapy could reasonably be left out.

The score is one input. Your oncologist reads it alongside tumor size, grade, node status, menopausal status, age, other health conditions, and how you feel about side effects. A score that falls inside a published trial band is not automatically the recommendation for you. Those trials had specific entry rules, and your situation may sit outside them. Node-positive disease, for example, was studied separately and later.

Results usually take one to three weeks after surgery. They often show up in your portal before anyone has talked them through with you. A number with no interpretation attached is not yet a decision. And treatment planning here is rarely urgent to the day. It is reasonable to wait for the conversation where the score is set next to everything else. Writing down your questions while you wait tends to make that conversation more useful.

• NCI Dictionary - Recurrence Score
• NCI Dictionary - Oncotype DX
• NCI - Breast Cancer Treatment (PDQ) Patient Version