[Radiotherapy using photons and neutrons in recurrences of colorectal tumors].

74 patients with locoregional recurrences of colorectal carcinomas were subjected to radiotherapy with photons. In 72% of the patients a palliative effect was seen with considerable or complete pain relief. The median survival times of the patients with and without remote metastases were 7 and 15 months, respectively. Radiobiological experience leads us to expect a higher degree of efficacy when using highly ionising radiation such as neutrons. The relatively poor physical parameters of conventional neutron generators were optimised by means of a novel irradiation technique developed at the German Research Centre in Heidelberg. Using this technique, a study was started for the combined photon/neutron irradiation in recurrent sacral tumours. 14 MeV neutrons of a DT (deuterium-tritium) generator ("KARIN" supplied by Haefely) were applied as boost. 26 patients have so far been treated by this method. Palliative results are excellent and the results obtained so far have been so encouraging that an extension of the study is under consideration.