| |
Chemoradiation In Cancer Therapy
By -
28-Jan-2009
Rate it :
Sole modality surgical treatment in cancer often fails because of the presence of micrometastatic disease or malignant cells beyond the surgical margins at the time of resection. Combined chemotherapy and radiation can address both these mechanisms of failure.
- Spatial cooperation is used to describe the action of onemodality to treat disease missed by another. This can be seen in small cell lung cancer, childhood leukemia where radiationis used to treat a potential sanctuary site, such asthecentralnervoussystem. Here the dose and timing of these modalities are adjusted to minimize central nervous system effects.
- Toxicity independence has been widely used in the designing of combination chemotherapy regimens, with improved therapeutic results seen by combining drugs with non-overlapping toxicities. When combining chemotherapy with radiation, drugs that enhance radiation-induced normal tissue damage may need to be avoided or timed sequentially (e.g., anthracyclines in adjuvant breast cancer treatment).
- Enhancement of tumor response secondary to an additive or synergistic effect is the focus of most concurrent chemoradiation regimens. This has resulted in organ preservation (larynx cancer, sarcoma of the extremities) without compromise of overall survival.Enhanced understanding of the radio-sensitization of chemotherapeutic agents implicate pathways involving increased initial damage (e.g., antimetabolites), repair inhibition of damage inflicted by ionizing radiation (e.g., platinum compounds), and redistribution of cell cycle phase, which will make cells more susceptible to damage by radiation (e.g., taxanes causing G2Marrest).
|