Omitting elective nodal irradiation and irradiating postinduction versus preinduction chemotherapy tumor extent for limited-stage small cell lung cancer: interim analysis of a prospective randomized noninferiority trial.
BACKGROUND
Controversies exist with regard to thoracic radiotherapy volumes for limited-stage small cell lung cancer (SCLC). This study compared locoregional progression and overall survival between limited-stage SCLC patients who received thoracic radiotherapy to different target volumes after induction chemotherapy.


METHODS
Chemotherapy consisted of 6 cycles of etoposide and cisplatin. After 2 cycles of etoposide and cisplatin, patients were randomly assigned to receive thoracic radiotherapy to either the postchemotherapy or prechemotherapy tumor extent as study arm or control. Elective nodal irradiation was omitted for both arms. Forty-five Gy/30Fx/19 days thoracic radiotherapy was administered concurrently with cycle 3 chemotherapy. Prophylactic cranial irradiation was administered to patients who achieved complete remission. An interim analysis was planned when the first 80 patients had been followed for at least 6 months, for consideration of potential inferiority in the study arm.


RESULTS
Forty-two and 43 patients were randomly assigned to a study arm and a control, respectively. The local recurrence rates were 31.6% (12 of 38) and 28.6% (12 of 42), respectively (P = .81). The isolated nodal failure rates were 2.6% (1 of 38) and 2.4% (1 of 42), respectively (P = 1.00). All isolated nodal failure sites were in the ipsilateral supraclavicular fossa. Mediastinal N3 was the only factor to predict isolated nodal failure (P = .004; odds ratio [OR], 29.33; 95% CI, 2.94-292.38). One-year and 3-year overall survival rates were 80.6%, 36.2%, and 78.9%, 36.4%, respectively (P = .54).


CONCLUSIONS
Preliminary results indicated that irradiated postchemotherapy tumor extent and omitted elective nodal irradiation did not decrease locoregional control in the study arm, and the overall survival difference was not statistically significant between the 2 arms. Further investigation is warranted.