gdpawel
Senior User
Joined: 15 Jan 2005
Posts: 123
Location: Pennsylvania
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 Posted: Fri Apr 08, 2005 3:20 am Post subject: Chemotherapy in Lung Cancer |
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Presently used chemotherapy drugs have a high rate of failure. This was brought out in a January 10, 2002 issue of the New England Journal of Medicine, when it was noted that twenty years of clinical trials using chemotherapy on advanced lung cancer have yielded survival improvement of only two months.
It also pointed out that while new chemotherapy regimens appear to be improving survival, when these same regimens are tested on a wider range of cancer patients, the results have been disappointing. In other words, oncologists at a single institution may obtain a 40% - 50% response rate in a tightly controlled study, but when these same chemotherapy drugs are administered in a real world setting, the response rates decline to only 17% - 27%.
Some patients with squamous non-small-cell lung cancer have been cured by surgery. The conventional treatment of choice is surgery. However, in patients with small-cell lung cancer, it is one of the very few forms of carcinoma for which chemotherapy has some positive effect on survival, but the effect is measured in terms of weeks or months, not years. Small-cell lung cancer tends to metastasize readily and grow rapidly. It is also believed that surgery may leave behind "some" stray cancer cells, which depends on the experience of the surgeon involved (a good thoracic surgical oncologist would make sure of enough margins to keep metastasis from occurring).
According to NCI, introduction of effective combination chemotherapy with or without chest radiation has led to four to five fold improvement in "median" survival (not long term survival) compared with survival of untreated patients and a small fraction of patients in whom the tumor was permanently eradicated.
The mechanisms by which primary tumors (like lung) produce brain metastases is "thought" to be hematogenous spread from primary or secondary sites in the lung. Since the brain has no lymphatic system, all tumors metastasizing to the brain do so by spreading through the bloodstream. Arterial blood passes through the lungs before entering the brain, and collects tumor cells filtered out in capillaries, which subsequently embolize to the brain.
Chemotherapy can affect the bone marrow's ability to make cells called platelets. These blood cells help stop bleeding by making the blood clot. In this case the bone marrow does not make enough platelets. This can cause a cancer patient to bleed or bruise more easily than usual, even without an injury.
Taxol/carboplatin fails to show clinical advantage over standard regimen in NSCLC. According to a multicentre Southwest Oncology Group study (9509), this is no significant differences in survival, response rates or quality of life between standard regimen Navelbine (vinorelbine tartrate) and dose-intense Taxol/Carboplatin treatment arms. Navelbine injection is indicated for first-line treatment of patients with unresectable, advanced NSCLC. Navelbine is the only single agent approved by the FDA in 20 years for the treatment of advanced NSCLC.
Taxol appears to increase the risk of lung inflammation and researchers suggest using it with caution (December, 2001 Journal of the National Cancer Institute). It is sometimes used along with radiation treatments since it is thought the drug might enhance the radiation's effects. The combination may cause more problems than it solves, like radiation pneumonitis. Radiation pneumonitis is a lung inflammation that occurs from radiation. It may develop about eight weeks after completing a course of radiation. Taxol increases the chance of having this problem. Symptoms include fever, difficulty breathing and a severe, dry cough.
Radiation pneumonitis may normally be rare, but researchers have found out that is much more common in patients who receive Taxol. This finding is highly significant and suggests that Taxol be used with caution, especially since Taxol has not been shown to have any clear benefit. |
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gdpawel
Senior User
Joined: 15 Jan 2005
Posts: 123
Location: Pennsylvania
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| Posted: Thu Nov 24, 2005 11:00 pm Post subject: Re: Chemotherapy in Lung Cancer |
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Some other chemotherapy agents that are used to treat NSCLC include Gemcitabine (Gemzar) and Docetaxel (Taxotere). The combination of Gemcitabine plus a platinum (either cisplatin, carboplatin or oxaliplatin) has been the most important drug combination introduced for the treatment of solid tumors in the past fifteen or so years. Clincal responses with this regimen have been unprecedented.
Gefitinib (Iressa) and erlotinib (Tarceva) are new drugs used to treat advanced NSCLC that is resistant to more conventional chemotherapy agents. They are referred to as tyrosine kinase inhibitors. They inhibit the activity of a substance called epidermal growth factor receptor tyrosine kinase, which is located on the surface of cells and is needed for growth.
Increasingly, targeted oral-dose anti-cancer drugs like Iressa and Tarceva are found to treat cancers effectively in those that it is helping, and seen as an intergral and necessary part of a patient's cancer care. A number of these breakthrough cancer drugs come only in oral form.
There are many cancer drug regimens, all of which have approximately the same probability of working. The tumors of different patients have different responses to chemotherapy. Tumors grow and spread in different ways and their response to treatment depends on these unique characteristics. The amount of chemotherapy that each patient can tolerate varies considerably from patient to patient.
Therapeutic protocols currently in use are limited in their effectiveness, because they are based on the results of clinical trials conducted on a general population, yet no two patients are alike. Which cancer drugs would be most effective? It would help to test the tumor first. It requires individualized treatment based on testing the individual properties of each patient's cancer.
Assay-directed chemotherapy is an individualized approach to killing cancer. Chemosensitivity testing, a method used to determine what precise medications would kill the particular cancer. Doctors have assumed that stopping cell division would stop cancer, because most cancer cells divide and grow rapidly. but the approach didn't always kill the malignant cells. Cancer isn't a case of cells growing out of control, but of cells refusing to die on schedule.
More and more physicians and patients are turning to individualized therapies to treat cancers. Under this approach, scientists study how an individual's cancerous cells respond to several drugs. Doctors have learned that even when the disease is the same type, different patients' tumors respond differently to chemotherapeutic drugs.
Without individualized testing, it's difficult to determine which drugs are best for patients who don't respond to standard therapies. |
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