Figure 2

Variations according to the year of surgery for the whole population. (A) The 5-year proportion of patients with metastases decreases regularly with the year of surgery from more than 20% in the 1950–1960s to <8% in 1999. (B) The tumour volume corresponding to 50% of patients with distant metastases during the first 5 years remains stable up to the beginning of the 1990s. During this period, differences in tumour size at treatment are sufficient to explain the decrease in the risk of metastases. After 1990, the tumour volume corresponding to 50% of patients with metastases increased rapidly from about 200 ml in 1990 to 2000 ml in 1999. During this period, the amount of tumour necessary for metastatic dissemination apparently increased. The reason is either a reduced metastatic potential of the tumours or a decreased viability of the metastases. (C) There was no marked change in the year of treatment in tumour volume corresponding to 50% of patients with involved axillary nodes. The capacity of tumours to involve lymph nodes was almost unchanged from 1954 to 1999. This observation contradicts the hypothesis of a reduction in the metastatic potential of tumours after 1990. Curves are displayed with the 95% confidence intervals.