Sixth interim progress report of the British Institute of Radiology fractionation study of 3F/week versus 5F/week in radiotherapy of the laryngo-pharynx.

The results are reported of the multicentre BIR fractionation trial of 3F/week versus 5F/week in radiotherapy of the laryngo-pharynx. 687 patient records have been analysed with respect to survival rates, recurrence-free rates and laryngectomy-free rates. For the group as a whole these analyses show no difference between the two fractionation regimes. Analysis of the sub-group which had early disease confined to the vocal cords does, however, show a better recurrence-free and laryngectomy-free rate for those patients treated with 5F/week, though the survival rate for the two groups remains similar. Acute and late normal tissue reactions are reported for up to six years after treatment. It appears that treatment with 3F/week can be given safely to patients with advanced disease. The differences between the two treatment groups who had early disease of the vocal cords are discussed, but until more data become available in the future the problems raised cannot be resolved.

The incidence of lung metastases in C3H mice after treatment of implanted solid tumours with x-rays or surgery.

C3H mice were implanted with pieces of spontaneous mammary carcinoma which were irradiated or removed surgically when they had grown to 6·5 mm mean diameter. The incidence of lung metastases was determined from samples taken at various times up to 6 months later. Single x-ray doses and fractionated schedules up to 15 fractions in 18 days were used, no significant difference being observed in the results for all these schedules.On the major question of whether radiation caused an increase in the number of lung metastases the study is inconclusive. The incidence of metastases was found to be 8% if the implanted tumour was cured by the radiation, whereas if the radiotherapy did not cure the tumours the incidence was 35%. This difference between the two groups was significant. If tumours recurred locally after radiotherapy and were then removed surgically, the incidence of lung metastases was significantly greater than that after surgery of unirradiated tumours. The incidence of metastases was similar after curative surgery and after curative radiotherapy.