• Ziqi Yue, PharmD

Differences in Metastatic Breast Cancer Treatment Guidelines Between the U.S. and China

Breast cancer is the most common cancer in women in China and the second most common cancer in the United States (CA Cancer J Clin, 2018; American Cancer Society, 2020). Over the past decades, many medications have been developed to treat metastatic breast cancer. With more and more treatment options available, guidelines in China and in the United States are constantly changing. This article will focus on treatment options in metastatic breast cancer, comparing the differences between the National Comprehensive Cancer Network (NCCN) guidelines in the United States and Chinese Society of Clinical Oncology (CSCO) guidelines in China.

HER2 positive:

Both the U.S. NCCN and China CSCO guidelines recommend using chemotherapy and HER2 targeted therapy as first-line treatment for metastatic HER2 positive patients. The preferred option in the United States is pertuzumab, trastuzumab plus taxane (docetaxel or paclitaxel). In addition to this regimen, pertuzumab, capecitabine plus taxane is another preferred treatment plan in China. Other treatment options include tyrosine kinase inhibitors (TKIs). Lapatinib and neratinib are the recommended TKIs to treat HER2 positive breast cancer in the United States (NCCN, 2020; CSCO, 2020). While in China, both lapatinib and neratinib are on the market, only lapatinib is recommended by CSCO guidelines in treating HER2 positive breast cancer. In 2018, China developed another TKI named pyrotinib. Pyrotinib plus capecitabine is the preferred treatment in China if the patient has not responded to trastuzumab (CSCO, 2020).

Hormone receptor positive:

Endocrine therapy with or without a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor is recommended by both guidelines. Endocrine therapies recommended in both countries include aromatase inhibitors (anastrozole, exemestane, and letrozole), estrogen receptor down-regulator (fulvestrant) and selective estrogen receptor modulator (tamoxifen and toremifene). These medications prevent estrogen from binding to the estrogen receptors through different mechanisms. CDK4/6 inhibitors are a class of drugs that can slow the growth of cancer cells. CDK4/6 inhibitors recommended in the United States include palbociclib (Ibrance), ribociclib (Kisqali), and abemaciclib (Verzenio). While in China, palbociclib is the only approved CDK4/6 inhibitor as of September 2020. Another difference between the treatment in China and the United States is the use of Histone deacetylase (HDAC) inhibitors. HDAC inhibitors stop the growth of cancer cells and stimulate cancer cell death by inhibiting DNA repair. This class of drugs is recommended only in China to treat hormone receptor positive breast cancer as a second-line therapy. It is recommended in combination with aromatase inhibitors by CSCO guidelines (NCCN, 2020; CSCO, 2020).

Genetic testing:

Gene mutation is an important factor in cancer. Genetic testing recommended in the United States include BRCA1 and BRCA2. Drugs recommended by U.S. NCCN guidelines to treat breast cancer patients with BRCA1 and BRCA2 mutations are olaparib (Lynparza) and talazoparib (Talzenna) (NCCN, 2020). Olaparib and talazoparib are oral targeted therapies that inhibit tumor cell growth by interfering with DNA transcription and repair. They are approved for patients who have previously received chemotherapy or endocrine therapy (Lynparza®, 2020; Talzenna®, 2018). While, in China, CSCO does not officially recommend olaparib for breast cancer patients with BRCA1 and BRCA2 mutations, the drug’s efficacy is mentioned in the guidelines (NCCN, 2020; CSCO, 2020). Talazoparib has not been approved in China as of September 2020 (National Medical Products Administration, 2020).

Want to learn more about different breast cancer treatment options available in China and in the United States? Contact RangeLight Health for a personalized second opinion from a top U.S.-based breast cancer specialist today.

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