As survival in group В was significantly longer than in group A, one might conclude that adjuvant radiotherapy was the causative factor. However, 50 percent of group A patients vs only 17 percent of group В had stage IV disease, and all four patients with stage IV disease in group A died of their metastases. At the time of endoscopic palliation, their disease was too far advanced to qualify for adjuvant therapy. This clearly made tumor stage a confounding factor. When we limited our analysis to the ten patients with stage IIIB squamous cell carcinoma, survival was not longer in group В any more. This underlines the importance of tumor stage for survival.
We agree with Hetzel and Smith, who in a recent review article on endoscopic palliation, pointed out the difficulties in interpreting results from inhomogeneous patient groups. Conclusions about factors influencing survival should be drawn only from data concerning patients with identical histologic features, tumor stage, and performance status. Further, survival data for patients having undergone elective procedures should be analyzed separately from data obtained in patients having had rescue procedures for life-threatening airway obstruction. As for the latter group, it is self evident that the procedure prolongs survival. Our data clearly show that stent patency is prolonged with a combination of endobronchial laser/stent treatment and adjuvant radiotherapy. In our opinion, combined therapy might increase survival as well, but this effect would have been missed in our study because of the small sample size.