Surgical stress and accelerated tumor growth

Delay in the initiation of radiotherapy after surgery is associated with an increase in local regional recurrence. A possible mechanism might be that remaining tumor cells proliferate significantly faster as a result of induced angiogenic cytokines. The growth rate of tumors arising from the inoculation of L44 tumor cells in the wound bed after surgical removal of L44 tumors was determined.

L44 tumors growing in the flank of female BN rats were surgically removed. In the wound bed, 5x10(6) L44 cells, harvested from the in vitro cell line, were injected. L44 cells were also injected in the contralateral flank and in control rats with and without surgical intervention. Tumor volumes as a function of time after injection of cells were recorded. From the attained volume at day 7, the cell doubling time was calculated, assuming 10(9) cells per cm3.

Tumors arising in the wound bed had the fastest growth rate as compared to the tumors in the contralateral flank or tumors in control rats with or without surgical intervention.

The results clearly indicate accelerated tumor growth after surgical stress. This indicates that delay in the initiation of radiotherapy after surgery with tumor cells remaining, results in a larger tumor burden and hence a higher probability of local recurrence.