PREVENTATIVE BRAIN RADIATION FOR LUNG CANCER
November 12th, 2009
A new study is taking a closer look at the benefits versus risks for lung cancer patients to undergo preventative brain radiation therapy as a means to stop cancer from spreading to the brain.
Study results show that while preventative brain radiation for patients with non-small cell lung cancer – the most common form of lung cancer – does reduce the chance of developing brain metastases, it impacts some short-term and long-term memory.
At 8:50 pm on November 16th, 2009 Gregory D. Pawelski said:
Is there a smart-pill alternative?
The idea that systemic therapies can be as effective as PCI, WBR or even stereotactic radiosurgy has been looked upon for a number of years now, with agents like Temodar and EGFR inhibitors against brain metastases.
The brain is the most common site of metastatic spread of lung cancer. Accumulating evidence suggests that systemic chemotherapy may play an important role. There have been clinical observations of frequent brain metastasis responses with systemic chemotherapy.
With a brain metastasis indicated or not, small molecule intervention can be beneficial by dissolving through the capillary cell membranes and absorbed into the brain. Systemic brain chemotherapy can also treat coexistent systemic disease.
Clinical data suggests that patients benefit both in terms of response and survival from drugs and drug combinations found to be “sensitive” to cancer cells rather than “resistant” to those cells.
The leading edge of research today is determing how a patient’s tumor cells work and hitting those pathways with multiple drugs, simultaneously or sequentially, each chosen because it targets one of those growth, replication and angiogenesis pathways. Matching tumor type to drug.
A drug like Temodar is small molecule. Empirically, it has been shown to cross the BBB to affect cell death in circulating tumor cells. Exciting results have come from studies of multitargeted tyrosine kinase inhibitors, small molecules that act on multiple receptors in the cancerous cells, like Tykerb and Sutent.
What may be another alternative is high doses of 2 small molecule EGFR pathway drugs, erlotinib (Tarceva) and gefitinib (Iressa), given together. These might cross the blood brain barrier and some patients get a long lived remission. High dose tamoxifen could then be given continuously as a potentiator.
It makes me wonder, if they radiate just the whole brain but not the spinal cord, how does PCI benefit the patient? Any theoretical cancer cells in the spinal cord would eventually infiltrate the brain.
The problem of penetration into the CNS is not as nearly as severe for small-molecule drugs. Large molecules cannot permeate through the narrow spaces, however, fat soluble (lipophilic) molecules can dissolve through the capillary cell membranes and are absorbed into the brain. A few brain diseases consistently respond to lipid-soluble small molecules.
Source: Cell Function Analysis