One of the problems in the treatment of small cell lung cancer is that, this cancer tends to spread to distant organs in the earlier phase of the disease. Cancer cells may have already harbored in distant organs by the time the treatment starts. There is some evidence to suggest that chemotherapy may decrease the risk of distant metastasis if given early during the course of the disease. One limitation with chemotherapy is that, it has no ability to penetrate in to the brain. Brain is one of the commonest sites of metastatic spread in small cell lung cancer. This fact has led to the suggestion that, for those patients who had good response to chemotherapy and radiation, and has no evidence of residual disease the brain can be radiated with the intention of preventing occurrence of metastatic disease. Yet the role of prophylactic cranial irradiation is controversial. Most studies have suggested that preventative brain irradiation, usually known as prophylactic cranial irradiation (PCI)
decreases the risk of development of brain metastasis, but have not shown to improve survival. There is also some concern about development of neurological impairment in patients who received prophylactic cranial irradiation. A recent meta-analysis (study of collection of all studies) has shown survival advantage with the use of prophylactic cranial irradiation. The fact that the improvement in survival is in the order of 5 percent only may be the reason why most of the studies failed to show survival advantage with prophylactic cranial irradiation. At this time it is reasonable to assume that prophylactic cranial irradiation gives a modest improvement in survival.
The current recommendations suggest using prophylactic cranial irradiation if only the patient has achieved a complete remission (complete disappearance of the tumor) with the combination of chemotherapy and radiation therapy.