Chemo: Yes or No? New Research Validates Oncotype DX

Patient Expert

Women diagnosed with breast cancer often face one of their toughest decisions early in treatment: should I undergo chemotherapy, or not? Building research shows that one particular test can make this decision a whole lot easier.

The expectant pause.

If you’re a breast cancer survivor, I’m sure you’ve experienced this. Your doctor has carefully laid out the pros and cons of two types of surgery: lumpectomy, or mastectomy. “Which would you like?”, he asks.

Or he’s got a really cutting edge clinical trial you’d be perfect for. Problem is, you won’t know which arm you’d be in: the one with the cool new treatment, or the one with no treatment at all. “Do you want to do it?”

Expectant pause.

And you think to yourself, “Hey, you’re the doctor – why don’t you tell me?” But that’s not how cancer treatment works. You’re faced with horrendously difficult decisions, some about altering your body permanently; some even life or death. And you’re expected to make those decisions – quickly.

Chemotherapy: yes or no?

Chemo is one of those decision points. For many survivors, it’s a given. Your tumor is large and aggressive—multiple lymph nodes are involved. But for those with smaller tumors, and little or no spread outside the breast (yet), the decision can go either way.

Do I go for chemo, blasting any rogue cancer cells with toxic doses of chemicals that will also cause my hair to fall out, make me deathly ill, and potentially leave me with lifelong side effects?

Or do I skip chemo and its fallout – and perhaps sign my own death warrant?

The Oncotype DX test

The Oncotype DX test has been offering women help with chemotherapy decisions for over 10 years. Based on genetic analysis of your tumor, the test can determine the likelihood of breast cancer recurrence within 10 years of your initial diagnosis.

You’re assigned a recurrence risk of low (0-10), medium (11-25), or high (over 25). Those with low scores could comfortably consider skipping chemo. Those with high scores would lean towards doing it. Those in the middle? Tough decision.

The challenge up to now was that the data used to develop the test was historical: i.e., it was based on analysis of tumors from women who’d already gone through treatment, with known outcomes.

But for truly accurate results, data has to be collected in real time: women receiving the Oncotype test, then researchers following those women for years afterward, waiting to see the outcome: do they survive, or die?

The TAILORx trial aimed to find out. Sponsored by the National Cancer Institute, the trial involved over 10,000 women in six different countries, all of whom received the Oncotype DX test. The results were recently published in the New England Journal of Medicine.

New evidence: Oncotype DX works.

The evidence is in: 5 years after diagnosis, 99.3 percent of the women with low Oncotype scores who chose NOT to undergo chemo are still alive. Many of these women would ordinarily have opted for chemo. But based on their Oncotype score, they took a chance – and won.

Is Oncotype DX right for you?

Oncotype DX isn’t for everyone; it’s limited to women with a diagnosis of hormone-receptive, HER2-negative, early stage breast cancer, with no spread outside the breast (about 100,000 Americans a year). But for those women – a substantial chunk of survivors – the test is a proven tool for making the tough chemotherapy decision.

Next up: how accurately predictive is Oncotype for women with mid-range scores – about 70 percent of women who take the test?

Researchers are continuing their initial study, and results should be known within a few years.

See more helpful articles:

Chemotherapy Regimens for Breast Cancer

Chemotherapy: Is It Always the Best Choice?

So You’re Having Chemo...

Risks and Benefits: Understanding the Statistics That Affect You

Fear of Recurrence: Where Do You Stand?

Oncotype DX Can Help Predict Chances of Breast Cancer Recurrence

Sources

Ducleff, Michaeleen. "Breast Cancer Gene Test Helps Predict Who Can Skip Chemo." NPR. September 28, 2015. Accessed October 17, 2015. http://www.npr.org/sections/health-shots/2015/09/28/444200042/breast-cancer-gene-test-helps-predict-who-can-skip-chemo.

Sparano, Joseph. "Prospective Validation of a 21-Gene Expression Assay in Breast Cancer — NEJM." New England Journal of Medicine. September 1, 2015. Accessed October 17, 2015. http://www.nejm.org/doi/full/10.1056/NEJMoa1510764.

Breast cancer survivor and award-winning author PJ Hamel, a long-time contributor to the HealthCentral community, counsels women with breast cancer through the volunteer program at her local hospital. She founded and manages a large and active online survivor support network.