How I Treat: HER2+ Breast Cancer

Case Presentation: Treating Patients With HER2+ Breast Cancer

Mridula George, MD

My name is Dr Mridula George. I am one of the breast medical oncologists at Rutgers Cancer Institute of New Jersey. I primarily treat women with breast cancer, both early‑stage breast cancer and metastatic breast cancer.

Today, I am just going to focus on how I treat early‑stage HER2‑positive breast cancer. HER2‑positive breast cancer is diagnosed in about 15-20% of women diagnosed with breast cancer. HER2 overexpression is associated with an aggressive clinical course.

However, in the last two decades, we have had multiple drugs that have been approved that target specifically the HER2. This has changed the landscape of this disease. The addition of HER2‑targeted agents have been studied in the metastatic setting, the adjuvant setting, the neoadjuvant setting.

In my practice, I prefer non‑anthracycline‑based chemotherapy, so my patients who are being treated in the neoadjuvant setting are treated with docetaxel, carboplatin, trastuzumab, and pertuzumab, which is given every three weeks for six cycles. After completion of six cycles, patients go on to have surgery.

Trastuzumab and pertuzumab, there is a risk of cardiac toxicity, so while patients are on treatment with the anti‑HER2 agents, we monitor their cardiac function routinely with an echocardiogram. Following surgery, we can decide on what the treatment should be for anti‑HER2 therapy based on the residual disease.

If patients have a pathologic complete response, we would continue trastuzumab and pertuzumab. With the dual anti‑HER2 therapy, pathologic complete response can be seen in over 60% of patients treated with dual anti‑HER2 therapy.

In patients who have residual disease, I switch their anti‑HER2 therapy to T‑DM1, based on the KATHERINE study, which showed that changing the anti‑HER2 agent in the adjuvant setting in patients who have residual disease did decrease the recurrence by almost half.

Patients, when their anti‑HER2 therapy is switched to T‑DM1, they receive 14 cycles of T‑DM1 in the adjuvant setting. Patients who have hormone receptor‑positive HER2‑positive breast cancer are started on hormonal therapy as well in the adjuvant setting.

All patients don't need neoadjuvant therapy. In patients who have less than two centimeters of invasive cancer in their breast and have clinically or radiologically node‑negative disease, they can go on to have surgery first.

In the adjuvant setting, they do benefit from the addition of anti‑HER2 therapy. Based on the APT study which was done, which looked at the combination of paclitaxel and trastuzumab given weekly for 12 weeks, followed by trastuzumab every three weeks to complete the year of therapy with anti‑HER2 agent, it showed an impressive disease‑free survival.

Even at 7 years, the 7‑year disease‑free survival was 93% and the recurrence‑free interval was 97.5%. Patients who have smaller tumors, stage 1 breast cancer, and they are node‑negative, they could be treated with a surgery first, followed by trastuzumab and Taxol in the adjuvant setting.

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