Advanced breast cancer often means severe disease, but why is it sometimes treated with just one drug instead of multiple drugs “together” as in early to mid-stage?
For some patients, multiple drugs are more toxic than more effective, so choose a single drug
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In fact, the chemotherapy regimens available for advanced breast cancer include single-agent chemotherapy and multiple-agent combination chemotherapy. In general, combination chemotherapy is superior to single-agent chemotherapy in terms of rapid tumor control. However, single-agent chemotherapy is relatively less toxic than combination chemotherapy. The aim of treatment for advanced breast cancer is mainly to control the tumor, improve the quality of life and maximize survival. Based on this aim, it is generally accepted that patients with advanced breast cancer can achieve rapid disease remission with combination chemotherapy, but survival time is not necessarily better than that of those treated with single-agent chemotherapy and is less toxic when treated with single-agent sequential therapy.
So, is it better to go with single or multiple agents?
- For patients with slow disease progression, less harmful tumors (i.e., low tumor load), poor general condition, and elderly patients, physicians generally consider single-agent chemotherapy.
- For patients with rapid disease progression, more harmful tumors, good general condition, and young age, physicians may choose a combination chemotherapy regimen.
After stable disease, single agent maintenance therapy is commonly used
After a period of treatment to achieve remission in advanced breast cancer, you will enter the maintenance phase, and for chemotherapy, maintenance therapy is usually done with a single agent.
- If the initial (first-line) treatment for advanced breast cancer is one drug and it works, doctors will generally continue to use that drug until the disease progresses.
- If the initial chemotherapy was a multi-drug combination and you may not be able to continue with multiple chemotherapy drugs because of adverse reactions, your doctor may consider choosing one of the original combination regimens to start maintenance therapy.
The ideal drug for single-agent maintenance chemotherapy should be therapeutically effective, relatively low toxicity, and easy to use over time, so physicians often choose oral chemotherapy drugs. The most used single-agent chemotherapy drug for breast cancer today is capecitabine. Capecitabine monotherapy in first-line treatment of advanced breast cancer can control tumor progression for up to 6 months, with a survival time of 24 months, and has low toxicity to blood cells and the heart, making it suitable for long-term use. The survival time of capecitabine monotherapy is better than the three-drug combination of cyclophosphamide + methotrexate + fluorouracil (CMF). Continuation of monotherapy maintenance with capecitabine after treatment with capecitabine in combination with other chemotherapeutic agents is currently a more reasonable treatment model for the full management of advanced breast cancer.
In addition, oral vincristine (Vinorelbine), etoposide, and cyclophosphamide can also be used as monotherapy maintenance therapy.
In conclusion, the choice of chemotherapy regimen for advanced breast cancer is a very specialized issue, taking into account various factors such as treatment efficacy, tumor type, patient’s systemic condition, side effects of treatment, and specific medical conditions, which should be considered and weighed by the physician to make a professional judgment.