The role of local treatment in the cure of cancer

Abstract

THE CONTRIBUTION of local control in the cure of cancer remains a matter of crucial importance. At diagnosis approximately 70% of patients with cancer have no detectable distant metastasis and over half of them are cured by loco-regional treatment only [ 11. In western Europe and the USA [2], out of 100 patients with cancer, approximately 22% are cured by surgery, 18% by radiotherapy (alone or associated with other agents in a combination in which radiotherapy has the prominent role) and 5% by chemotherapy (alone or in combination but with the leading role to chemotherapy). Since the use of combination treatments is becoming of increasing importance these figures are tentative. Suit [3] has stressed that one third of patients who die do so as a consequence of failure to control loco-regional disease. This is in particular the case in patients with head and neck, gynaecological, genito-urinary and gastrointestinal cancer, bone and soft tissue sarcomas, and tumours of the central nervous system [ 11. Hence, one of the main potential sources of progress is to improve loco-regional control. However since approximately half the patients whose death is caused by local extension have occult metastases at the time of initial treatment, the potential benefit related to an improvement in local control amounts to only 8-10% of patients. Nevertheless about half of the progress in the cure-rate which can be expected in the next two decades, will result from advances in local treatment and the other half from advances in systemic treatment [4]. These two fields of research are not competitive but complementary. In patients with overt or occult distant metastases, success or failure mainly depends upon the results of systemic treatment, however the role of local treatment is also important. In patients without metastases at diagnosis the cure depends upon the effectiveness of local treatment. Improved methods eradicating the primary tumour may reduce the death rate by two mechanisms--prevention of local tumour extension and reduction of distant metastases. The effect of local extension is illustrated by the results of the EORTC trial on non-small cell lung cancer in which conventional radiotherapy (RT) was compared with RT combined with daily administration of small doses of cisplatin used as a radiosensitiser. The 3-year survival rates were, respectively 2% and 16%, P = 0.009 [5]. In a recent meta-analysis [6] carried out on over 2000 patients with limited small cell lung cancer included in 13 trials, the long term survival was slightly but significantly higher in patients treated by RT+ chemotherapy (CT) than in patients treated by CT alone (14% vs. 9%). The second beneficial effect of securing local control is related to the reduction in the incidence of distant metastases. Local residual disease may constitute a nidus for distant dissemi-