Growth rate of primary breast cancer and prognosis: observations on a 3- to 7-year follow-up in 180 breast cancers.

The disease-free probabilities after 3 to 7 years of follow-up of 180 breast cancers of known doubling times were studied to assess the prognostic significance and clinical implications of the growth characteristics of primary breast cancer. Fast-growing tumours, N+ greater than 3, showed a prognosis significantly worse (P less than 0.01) than that of slow-growing tumours of the same class; no significant differences were found among N- or N+ (1-3) fast-, intermediate- and slow-growing tumours. Highly significant differences were found among fast- and intermediate-growing tumours with different degrees of lymph node involvement (respectively P less than 0.0001 and P less than 0.001), with the worst prognosis for N+ greater than 3 tumours. In contrast, no significant differences were found among slow-growing tumours of the different N classes. When the Cox model was applied, the relationship between lymph node involvement and doubling time was significant, as was the interaction term. It is suggested that growth rate and metastatic potential are not the same in primary breast cancers, and their relation should be investigated.