You’ve taken tamoxifen or Arimidex for 5 years. Your oncologist wants you to continue for another 5; you want to quit. A newly developed biomarker test may someday be able to help break the deadlock.
When I was diagnosed with breast cancer 12 years ago, the treatment plan my oncologist developed was based on a long-standing model called the Clinical Tumor Score (CTS). Derived from information in the patient’s pathology report, the CTS factors in size and grade of the tumor; whether or not the cancer has spread to lymph nodes; the patient’s age, and proposed treatment.
I’d had surgery; the question was, did I need radiation and/or chemotherapy? And would long-term hormone therapy (HT) help lower my risk of recurrence?
My case was pretty straightforward; I needed radiation to clean up the area around a "dirty" lymph node. And my age and diagnosis made HT - at that time, tamoxifen - a given, as well.
But it was chemotherapy that was the sticking point. Gary, my oncologist, said he recommended it, but wouldn’t push if I decided not to have it; he felt that I was over the "Yes, you need chemo" line - but not that far over. He felt chemotherapy might lower my recurrence risk by about 8%.
Tough-decision time. Did I want to go through the hair loss, the nausea, the mouth sores (and side effects I didn’t even know about) for that 8% gain?
I decided I did. I had a family, a young son; a life I loved. So I did the chemo.
And today, in retrospect, I question whether I made the right decision. With lasting (permanent, it seems) side effects, I’m not so convinced the 8% was worth it.
Fast forward a few years from my initial diagnosis. It’s 2007, and a new test, Oncotype-DX, is gradually making its way into oncologists’ offices. This test would have been part of my initial diagnosis; based on the actions of 21 specific genes - a genetic fingerprint specific to each patient - Oncotype-DX is able to predict with quite a bit of accuracy how likely a woman is to experience a recurrence. Low likelihood? You can safely consider skipping chemo. High likelihood? You’d better have it. Oncotype-DX is now a regular part of most women’s diagnostic process.
As it turns out, though, Oncotype (and its lesser-known equivalent, IHC4) is reassuringly accurate at predicting recurrence the first 5 years out from diagnosis; but less so in succeeding years. And, since more than 50% of estrogen-receptive tumors recur after (not within) 5 years (Osterweil, 2012), Oncotype can only predict risk so far.
Now there’s a new test, the BCI (breast cancer index) assay; and it’s showing positive results in predicting risk during that crucial 5- to 10-year period post-diagnosis.
The online journal Lancet Oncology published a prospective comparison study based on data from 665 breast cancer survivors in late September_._ Women in the study were post-menopausal; their cancer was estrogen-receptive, and it hadn’t spread beyond the breast (no lymph node involvement). The women had all received 5 years of hormone therapy - either tamoxifen, or Arimidex.
Performing the test on archived tumor samples, BCI was able to accurately distinguish 60% of patients at low risk for recurrence, and 40% of those at high risk. Recurrence rates ranged from 4.2% (low risk) to 30% (high risk). ("Gene expression," 2013)
And here’s where the decision regarding duration of HT comes in. Using the BCI test, your doctor will be able to tell you right up front whether data shows you should follow up your initial treatment with 5 years of hormone therapy - or 10.
What’s the big deal, you ask? Why not go for the 10-year treatment, just to be sure?
Because many - indeed, most - women experience side effects from HT, ranging from weight gain to joint pain to fatigue to potentially fatal blood clots. HT works; but it’s not pleasant. Undergoing HT for 5 years beyond its best effectiveness is a questionable step.
Interested in the BCI test? Ask your oncologist about it. BCI and/or Oncotype-DX are a couple of useful tools in refining the cancer diagnosis for most survivors.
Gene-expression-based biomarker predicts long-term risk of breast cancer recurrence. (2013, September 13). Retrieved from https://www.redorbit.com/news/health/1112947185/gene-expression-based-biomarker-predicts-long-term-risk-of-breast-cancer-recurrence/
Osterweil, N. (2012, December 07). The best assay to predict breast cancer late recurrence is". Retrieved from https://www.medscape.com/viewarticle/775807
Sgroi, D. (2013, September 12). Prediction of late distant recurrence in patients with oestrogen-receptor-positive breast cancer: a prospective comparison of the breast-cancer index (bci) assay, 21-gene recurrence score, and ihc4 in the transatac study population. Retrieved from https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(13)70387-5/abstract
Last updated: July 16, 2014
PJ Hamel is senior digital content editor and food writer at King Arthur Flour, and a James Beard award-winning author. A 16-year breast cancer survivor, her passion is helping women through this devastating disease. She manages a large and active online survivor support network based at her local hospital and shares her wisdom and experience with the greater community via HealthCentral.com.