Concomitant resistance and early-breast cancer: should we change treatment strategies?

The dynamics of disease recurrence shows a bimodal pattern with a fairly broad dominant peak at about 1.5-2 years after surgery followed by a second peak at about 5 years. Nowadays, this clinical pattern is explained by assuming that primary breast tumours as well as their metastases have phases of both arrested (tumour dormancy) and active Gompertzian growth. Tumour dormancy at metastatic sites is currently ascribed to biological particularities of local tissue microenvironments that inhibit the growth of tumour cells. However, in some patients, tumour dormancy appears to also depend on the direct interplay between the primary tumour and those metastases, a biological phenomenon called "concomitant resistance". Concomitant resistance is related to three biological processes: concomitant immunity, tumour-induced angiogenesis and athrepsia. Concomitant resistance can explain the bimodal relapse pattern of breast cancer patients as well as many other clinical phenomena such as the better clinical outcome among patients surgically treated during the putative early luteal phase, or the worse clinical outcome of African-American premenopausal women. Any therapeutic interventions (even surgery) can affect concomitant resistance with the potential to induce a worse as well as a better clinical outcome. This should be taken into account when planning new treatment strategies.