Koscielny  and  Tubiana (1) studied  3679 breast cancer patients. None of them displayed metastasis at the time of diagnosis, nor  before being treated. None received adjuvant chemotherapy. 663 (18%) patients had a local recurrence (LR+). The following figure published by the authors  (Fig. 2) depicts the monthly rate of metastasis-emergence following the initial treatment.

During the first year or so the metastatic rate rises whereupon it declines. In patients who  had a local recurrence (LR+) the peak is more pronounced than in the rest without a local recurrence (LR-). Now compare this curve with  the relapse rate following breast cancer surgery (1)

And the curve describing the hazard rate in breast cancer

All three are manifestation of the same phenomenon: The patient depends somehow on her tumor and  upon its removal she grows additional tumor tissue, either in form of a local relapse or  as metastasis. Please note that the metastatic rate in patients whose tumor did not relapse locally (LR-), is lower than that observed in patients whose tumor reappeared locally (LR+). The first are less tumor dependent than the other.

From the third year and onward cancer proceeds through two phases: Compensated when the hazard rate declines and de-compensated when it rises. During compensation the meatstatic rate and the probability of a relapse are low.

The therapeutic implication is straight forward: As long as tumor does not impinge upon a vital function and does not cause pain or suffering it ought to be left intact. Treatment ought to preserve the tumor and alleviate its secondary manifestations.

Additional reading

1. Pernicious cachexia
2. Bi-modal hazard rates (BMH)
3. Allometric law of metastasis

References

1. Serge Koscielny  and Maurice Tubiana
The link between local recurrence and distant metastases in human breast cancer
International Journal of Radiation Oncology*Biology*Physics
Volume 43, Issue 1, January 1999, Pages 11-24
2. M. Retsky, R. Demicheli and W. J.M. Hrushesky
Does surgery induce angiogenesis in breast cancer? Indirect evidence from relapse pattern and mammography paradox  International Journal of Surgery  Volume 3, Issue 3 , 2005, Pages 179-187