By the time a tumor is 5 mm in diameter it has undergone approximately 20 doubling times and represents almost 10th to the 8th cells.
An occult 1 gm tumor may contain up to 1×10 to the eighth cells, all of which are connected to the circulation due to the need for oxygen and nutrients.
A 10 mm mass has approximately 10th to the 9th cells.
A 30 mm mass has approximately 2.7 x 10 to 10th cells.
Death usually results when a tumor burden reaches 10 to the 12th cells.
Neovascularization required for a tumor to grow beyond 1-3mm.
Production rate of new cells determined by number of cells in the growth fraction and length of their cell cycle.
Net growth rate of a tumor must account for cell loss which is due to differentiation, degeneration, necrosis, apoptosis, resorption by immunologic cells, exfoliation and metastases.
Unlike normal tissues the production of cells in a tumor exceeds cell loss.
Studies in animal models suggest surgery increases the number of circulating tumor cells and can potentiate the growth of metastatic disease.
Metastatic tumor growth correlates with a reduction and angiogenesis inhibitors following removal of the primary tumor.
Resection of a primary tumor in the presence of metastatic disease will enhance the growth of distant lesions (Gunduz N et al, Fisher B et al).
Protein factor is synthesized by primary tumors restrict tumor growth at metastatic sites, so that such lesions grow once the primary lesion is resected (Fisher B et al, Folkman J).
Surgery enhances the production of oncogenic growth factors such as transforming growth factor alpha which can increase tumor growth.