Kinetic analysis of recurrence and survival after potentially curative resection of nonsmall cell lung cancer

Abstract

Background About two-thirds of the patients with nonsmall cell lung cancer (NSCLC) who undergo a potentially curative resection eventually suffer from recurrent disease. However, it has yet to be elucidated as to how survival after recurrence is influenced by different variables, including timing, type of recurrence, or other clinicopathological features. There have been few studies concentrating on the kinetics of growth of occult micrometastatic tumor cells that eventually manifest as tumor recurrence. Methods We retrospectively reviewed the charts of 197 patients who developed recurrence after a potentially curative resection for NSCLC. Results The median disease-free interval was a little over 1 year (395 days), as was the median postrecurrence survival—383 days. We created a model for the kinetics of recurrence by assuming that: (1) a tumor of 10⁹ cells is the usual limit of detection, (2) patients generally die before the tumor reaches 10¹² cells, and (3) it takes 1 year for average lung cancer cells to show a 10-fold increase. The model indicated that as much as 10⁹ tumor cells should have been present immediately after the operation. Alternatively, the residual tumor cells should have an accelerated growth after the surgery. Conclusions These models indicate the importance of developing a sensitive detection method for occult metastatic cells and to understand the tumor dormancy mechanism.