Adjuvant Therapy Options for HR+ Breast Cancer

EP: 1.Introduction: A 54-Year-Old Woman With ER+/PR+ Breast Cancer

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EP: 2.Adjuvant Therapy Options for HR+ Breast Cancer

EP: 3.CDK4/6 Inhibitor Breast Cancer Clinical Trials

EP: 4.Common Adverse Events With CDK4/6 Inhibitors

EP: 5.Case Patient Prognosis

EP: 6.ER+ Early Breast Cancer Future Directions and A Note on Ki-67 Analyses

Lowell Hart, MD, FACP: Well, in a broad way of speaking the systemic adjuvant treatment of early breast cancer falls into 2 groups. There’s the chemotherapy side and the hormonal therapy side.

For a postmenopausal woman like this, the hormone therapy side would be either an aromatase inhibitor of which there are 2 that are commonly used, anastrozole [Arimidex] and letrozole [Femara], or tamoxifen, which has been around for 30 to 40 years now. It can be used in either pre- or postmenopausal women.

Based on the data from several trials, ATAC and other trials that were done a decade or so ago, most postmenopausal women in the United States do get aromatase inhibitor and that’s what I generally speaking will use.

As far as a chemotherapy regimen, they sort of fall into 2 categories. There’s the ones containing anthracycline, of which the most commonly used in the United States would be the so-called ACT regimen, usually given in a dose-dense fashion with Adriamycin [doxorubicin], cyclophosphamide, and paclitaxel [Taxol].

Then there are regimens that are nonanthracycline, which is generally speaking are what I prefer in patients like this where we’re going to be focusing on the hormonal side. I do believe for patients like this with high-level estrogen receptors, the majority of the benefits that they get is from the hormonal treatment, which is going to be continued for a longer time.

There is definitely benefit from chemotherapy in this type of patient that’s been proven in the RxPonder trial, but I think still the majority benefit, especially now that we can add abemaciclib [Verzenio] CDK4/6 inhibitor in to beef up the hormonal therapy for these high-risk patients, I do think that’s the majority of the benefits.

That’s why I personally, in this type of patient would try to avoid anthracycline. I’ve been in practice long enough that I’ve had a couple of patients develop late myelodysplasia [a group of disorders caused when something disrupts the production of cells] or leukemia, which I think has been from them having received anthracycline adjuvant chemotherapy.

I have 2 patients that I can think of that have had that happen later on many years after their treatment. So, when possible, I like to avoid anthracycline in patients.

There’s also of course the risk of cardiac issues later in life. Now that the hormonal therapy has been strengthened in these patients, I think there’s even less need to use anthracycline for patients like this.

This transcript has been edited for clarity.

Case: A 54-Year-Old Woman with ER+/PR+ Breast Cancer

Initial Presentation

• A 54-year-old, postmenopausal woman presents with a newly diagnosed lump in her right breast
• She has no family history of cancer and underwent menopause at age 50

Clinical work-up

• Imaging demonstrated a 2.4-cm solid mass in the right upper quadrant with no suspicious lymphadenopathy identified
• Core biopsy: positive for invasive ductal carcinoma, ER 100%, PR 97%; HER2 1+ and FISH negative; Ki-67 45%; modified Bloom-Richardson grade 3
• Lumpectomy and sentinel lymph node biopsy performed
  • Tumor size is 2.4 cm, and 3 LNs are positive for metastatic disease
• 21-gene assay recurrence score is 30
• pT2N1M0, stage IIB
• ECOG PS is 0

Treatment

• Patient underwent partial mastectomy with no residual disease
• She is given radiation therapy to intact breast
• She is started on adjuvant chemotherapy with cyclophosphamide and docetaxel

Followed by adjuvant therapy with AI + 2 years of abemaciclib