Cancer and Wisdom of the Body: Diagnosis delay in breast cancer

In a study published in the BMJ (1) Elwood and Morehead studied the effect of treatment delay on survival of 1591 females with breast cancer in British Columbia. The interval between the first symptom and treatment was recorded and correlated with survival. The chart depicts the distribution of delay times among the patients

The following figures were copied from the original publication. Figure 2 depicts relative survival of two groups experiencing short and long delay. Up to the fifth year (marked by an A) survival of the long delayed was better than that of the short delayed. Later on (marked by a B) the short delayed had a better survival. A similar crossing over of the relative survival curves occurs after the tenth year (Fig. 3)

This study supports the present hypothesis that the patient depends upon her tumor and its removal raises her probability to die (hazard rate). Patients in which cancer had spread beyond the breast (metastasis) depend less on their local tumor and their hazard to die does not rise. This explains why initially the long delayed patients had a better survival. During this period their tumor seeded metastases, and when the local tumor was removed, they were protected by their metastases and their hazard did not rise.
Although the difference between the curves was not significant (not even in Fig. 2) the trend is obvious.

References

1. Elwood MJ and Moorehead WP Delay in diagnosis and long-erm survival in breast cancer.
British Medical Journal 31 May 1980 p. 1291-1294