[Local efficiency of percutaneous radiotherapy in lung cancer. Analysis of 215 repeated bronchoscopies in relation to applied radiation dosage].

PURPOSE

During a locoregional radiotherapy with curative attempts of lung cancer patients bronchoscopic examinations with biopsies and/or cytologic lavages were repeated to assess the accuracy of limiting the total dose to 60 Gy. In order of the applied dose macroscopic changements of the endoluminal tumor and microscopic elimination should be made out. The correlation between macro- and microscopical regression should allow a statement about reliability of single results. The clinical course and a conventional thoracic X-ray examination seemed to be a to large-meshed screen to evaluate the effect at the end of therapy. The aim was to improve the criterias of success and to adapt and optimize the radiation dose individually.

PATIENTS AND METHODS

The prospective, together with the pneumologists, defined treatment concept included the repetition of bronchoscopic evaluations after the application of 60 Gy and 80 Gy. These radiation doses from 60 Gy up to 80 Gy have been given with a shrinking-field technique to the mediastinum and the primary. In order to record statistically the optical tumor changements we were urged to create a so-called bT-score. The structure of this score was orientated towards the periphery of the tracheobronchial tree.

RESULTS

Hundred and forty-four patients with endoscopically and histologically verified bronchogenic carcinomas were treated. On the subjects 215 re-bronchoscopies accomplished with biopsies were performed and allowed to analyze the macro- and microscopical behavior under treatment. A histological/cytological elimination of tumor was achieved after 60 Gy in 35.1%, after 80 Gy in 62.3%. Macroscopically no tumor was visible after 60 Gy in 43.6%, after 80 Gy in 82%. A correlation between identical micro- and macroscopical observations was only seen in 61%, respectively in 71%.

CONCLUSIONS

The escalation of the radiation dose from 60 Gy up to 80 Gy with shrinked fields could increase the local tumor sterilization rate by 1.8 times from 35.1% to 62.3%. The refining and completion of usually known parameters by endoscopical and histological examinations seems to be an acceptable way to define individual radiation doses. The quality of the performed therapy can be better determined. A predestination of the total dose to a limit of 60 Gy does not ensure a macro- and microscopical elimination of the tumor and may be inferior to an individually adaptation of the dose.