A Guide to 5 Medications for Breast Cancer
Choosing among breast cancer treatment medications can feel overwhelming at diagnosis. This guide explains five widely used, FDA-approved breast cancer treatments one by oneâwhat they are, who typically receives them, how theyâre given, and key safety notes. Your care team will tailor choices based on tumor biology (hormone receptors, HER2 status), stage, and overall health. Use this overview to prepare informed questions for your next visit.
1) Tamoxifen (Selective Estrogen Receptor Modulator)
What it is: A blocked âsignalâ for estrogen. Tamoxifen attaches to estrogen receptors on breast cancer cells so estrogen canât drive growth.
Who itâs for: People with hormone receptorâpositive (HR+) early-stage or metastatic disease, including many premenopausal patients; also used after DCIS treatment and for risk reduction in selected high-risk adults.How itâs given: Oral tablet once daily, typically for 5 years in early-stage disease; duration may extend based on risk and clinician guidance.Benefits: Lowers the chance of recurrence and new cancer in the opposite breast; improves long-term outcomes in HR+ disease.
Key safety and monitoring: Hot flashes, rare blood clots, and uterine changes; clinicians weigh benefits and risks and monitor as needed.
2) Anastrozole (Aromatase Inhibitor)
What it is: A blocker of estrogen production. In postmenopausal adults, most estrogen is made outside the ovaries; anastrozole reduces that production.
Who itâs for: Postmenopausal adults with HR+ early-stage disease after surgery (adjuvant therapy) or advanced/metastatic HR+ disease, including after tamoxifen.
How itâs given: Oral 1 mg once daily for a defined adjuvant course or while effective in advanced disease.
Benefits: Lowers recurrence risk and is a backbone option for postmenopausal HR+ patients; longer total endocrine therapy (7â10 years) can help selected higher-risk groups.
Key safety and monitoring: Joint aches and bone density loss; teams often add bone-health strategies and periodically check bone density.
3) Trastuzumab (HER2-Targeted Monoclonal Antibody)
What it is: A targeted antibody that binds the HER2 protein on cancer cells, disrupting growth signaling.
Who itâs for: HER2-positive early and metastatic breast cancer, confirmed by FDA-approved HER2 testing.
How itâs given: Intravenous infusions, commonly every 3 weeks; in early-stage disease itâs typically continued for about one year, often with chemotherapy.
Benefits: Improves disease-free and overall survival when added to chemotherapy; a cornerstone of care in HER2-positive disease.Key safety and monitoring: Possible heart function decline; guidelines and labels recommend baseline and periodic cardiac monitoring (e.g., echocardiography or MUGA) during treatment.
4) Palbociclib (CDK4/6 Inhibitor)
What it is: A cell-cycle blocker. Palbociclib inhibits CDK4/6, proteins cancer cells use to divide.
Who itâs for: HR-positive, HER2-negative advanced or metastatic breast cancer, used with endocrine therapy (an aromatase inhibitor first line, or fulvestrant after prior endocrine therapy).How itâs given: Oral treatment in 28-day cycles (21 days on, 7 days off) with routine blood-count checks.
Benefits: Extends the time before disease progression compared with endocrine therapy alone, allowing longer disease control at home.
Key safety and monitoring: Neutropenia is common but usually manageable with dose holds or reductions; labels specify CBC monitoring at baseline, day 15 of the first two cycles, and each cycle start. Rare interstitial lung disease has been reported.
5) Pembrolizumab (Immune Checkpoint Inhibitor, anti-PD-1)
What it is: An immunotherapy that helps the immune system recognize and attack cancer cells by blocking the PD-1 pathway.
Who itâs for: Triple-negative breast cancer (TNBC) in two key settingsâcombined with chemotherapy before surgery for high-risk early-stage disease, then continued after surgery; and in metastatic TNBC meeting PD-L1 criteria, typically with chemotherapy.How itâs given: Intravenous infusion at fixed intervals per regimen.
Benefits: Increases pathologic complete response rates in high-risk early TNBC and improves outcomes in selected metastatic TNBC.
Key safety and monitoring: Immune-related side effects (thyroid, liver, lung, skin, colon) can occur; early reporting enables prompt steroid treatment when needed.
When chemotherapy is still essentialâand how to talk with your team
Chemotherapy remains foundational in many plansâespecially for TNBC and HER2-positive disease (where itâs paired with trastuzumab)âand in select HR+ cases. Discuss common chemotherapy drugs for breast cancer such as taxanes and anthracyclines, how they pair with targeted agents, and how supportive medicines can prevent nausea and protect blood counts. Bring a medication list to every visit, ask about timing with oral therapies, and confirm which symptoms warrant immediate calls versus routine check-ins. Pairing treatments with screening awareness matters too; know typical breast cancer symptoms and detection steps so early signs of breast cancer prompt timely imaging and follow-up.
Conclusion
Modern regimens match the right mechanism to the right tumor: hormone therapy medications for breast cancer for HR+ disease, targeted therapy for breast cancer for HER2-positive tumors, immunotherapy for breast cancer in defined TNBC settings, and chemotherapy where indicated. Use this one-by-one guide to frame questions on benefits, risks, and monitoring. Your oncology team can personalize choices so treatment fits both your cancer biology and your life.