However, in one older Veterans Administration study in which limited-disease SCLC made up less than five percent of all resectable lung cancers, patients were treated with surgery and adjuvant, older chemotherapeutic agents. Although adjuvant chemotherapy is often given after resection of stage I SCLC, there are no randomized studies with a no-treatment arm supporting such therapy. After being given induction chemotherapy, patients were randomized to surgery or no surgical resection, followed by thoracic and brain irradiation in both groups. About 40 percent of SCLC patients present with limited stage III disease. Treatment involves combination chemotherapy regimens, usually combined with radiotherapy.
Survival continues to decrease thereafter, with only about five percent of patients cured.
Several randomized trials have shown that mediastinal radiotherapy is beneficial, resulting in a reduction in the rate of localized relapse. A meta-analysis of randomized trials shows that thoracic radiotherapy, used in conjunction with combination chemotherapy, moderately improves survival, particularly in younger patients. The optimal dose and timing of radiotherapy remain to be determined. Initial chemotherapy followed by mediastinal irradiation and prophylactic cranial irradiation appears to produce the best results. The administration of cranial irradiation in patients in remission reduces the CNS relapse rate from 30 or 40 percent to five or 10 percent, but it does not prolong survival.