Prophylactic cranial irradiation in limited stage small cell lung cancer: survival benefit in patients with favourable characteristics.

The value of prophylactic cranial irradiation (PCI) in the treatment of small cell lung cancer (SCLC) remains controversial. As part of a randomised study investigating the timing of chest irradiation (CI) with respect to combination chemotherapy, the effect of PCI was evaluated. Between 1981 and 1989, patients were randomised to initial chest irradiation ICI (99 patients) or 18 weeks delayed late chest irradiation LCI (100 patients). PCI was given to 157 patients. In the beginning, only ICI patients received PCI, but in October 1984 the strategy was changed so that all patients received PCI. Thus, the patients who did not receive PCI were randomly allocated. The PCI dose was 33 Gy/11 fractions (45 patients) and 25 Gy/11 fractions (112 patients). The 2-year CNS-recurrence rate (+/- standard error) was significantly lower in patients who received PCI, 16.3 +/- 4.1%, than in those who did not, 55.1 +/- 12.4% (p = 0.01). In contrast, the 2-year cause-specific survival was not significantly different, 24.9 +/- 3.6% and 16.9 +/- 6.2% (p = 0.31). The 2-year progression-free rates with or without PCI were 18.5 +/- 3.3% and 11.4 +/- 5.4%, respectively (p = 0.58). To test the hypothesis that a benefit from PCI would mainly be expected among the patients with the best prognosis, a multivariate regression analysis of prognostic factors was undertaken. Based on weight loss, performance status, serum sodium and age, the third of the patients with the best prognosis were identified. In that group of patients, the survival advantage from PCI was statistically significant, 35.5 +/- 7.2% versus 14.1 +/- 8.0%, P = 0.029. These results are currently being tested in a Danish multicentre trial where patients with a good prognosis are randomised either to receive PCI or not to receive PCI.