Lung cancer is a major health problem and the leading cause of cancer death worldwide, according to the World Health Organization. There are two major types of lung cancer: small-cell lung cancer and non-small-cell lung cancer. Chemotherapy is widely used to treat advanced and metastatic lung cancer.
Classification
Chemotherapy treatment for lung cancer can be classified into two groups.
The first group consists of non-specific cytotoxic agents such as cisplatin, carboplatin, etoposide and paclitaxel (Taxol). These agents can cause damage to cancer cells (hence, the name cytotoxic), stop cancer cells from growing and dividing and ultimately kill the cancer cells. These agents are used for all lung cancer patients. Non-specific cytotoxic agents are often combined to enhance their therapeutic effects. The most common combination chemotherapies for lung cancer include cisplatin and paclitaxel, cisplatin and gemcitabine, cisplatin and docetaxel, and carboplatin and paclitaxel. These combinations are often used as the initial (first-line) treatment for lung cancer.
The second group consists of chemotherapy agents designed to target certain types of cancer cells. Targeted agents are effective only for a small subset of lung cancer patients. Targeted agents are often used as the second-line treatment for advanced and metastatic lung cancer, when patients fail to respond to the initial treatment or when patients relapse following an initial response.
Effectiveness of Cytotoxic Agents
Lung cancer patients treated with cytotoxic agents have a 5-year survival rate of 5 percent to 50 percent depending on stage of lung cancer at diagnosis. The lowest survival rate is among patients with advanced or metastatic lung cancer.
Treatment of advanced lung cancer using non-specific cytotoxic agents is not very effective. Roughly 20 to 30 percent of patients respond to these agents. Patients with advanced lung cancer treated with standard chemotherapy based on cytotoxic agents have a median length of survival of 8 to 10 months, according to the book "Clinical Oncology." That means half of advanced lung cancer patients treated with chemotherapy will die after 8 to 10 months.
Most notably, there is no evidence that one combination chemotherapy is better than another in terms of efficacy. For instance, a 2002 study published in "New England Medical Journal" reported that none of the four chemotherapy regimens (cisplatin and paclitaxel, cisplatin and gemcitabine, cisplatin and docetaxel, and carboplatin and paclitaxel) offered any benefit over others for treatment of advanced lung cancer.
Effectiveness of Targeted Agents
Bevacizumab (Avastin) is one of the targeted agents approved by the Food and Drug Administration (FDA) to be used in combination with standard platinum-based chemotherapy for treatment of advanced lung cancer. According to a 2009 review published in "Oncogene," the benefit of adding bevacizumab to standard chemotherapy for advanced lung cancer is minimal.
Cetuximab, another targeted agent, has been shown to improve the survival length of patients diagnosed with advanced lung cancer by 1 month, the review reported.
Effectiveness of New Chemotherapy Treatments
Recently, several new cancer drugs have been developed to target patients with cancers that have epidermal growth factor receptor (EGFR) mutation. EGFR regulates many important cellular functions including dividing and growth. Patients with EGFR-mutation tumors account for 10 to 15 percent of all lung cancer patients.
Patients with EGFR-mutation tumors respond well to drugs targeting EGFR. The response rate can be as high as 70 to 80 percent. According to "Oncogene," these agents can potentially increase length of survival of eligible patients by 6 to 8 months.
Expert Insight
Patients treated with EGFR-targeted agents (e.g. gefintinib, erlotinib) tend to develop resistance to the drugs after 10 to 12 months.
