Method
Thirty-one breast cancer patients who had undergone curative surgery were randomly assigned to an exercise group (n=16) and a non-exercise group (n=15). Exercise therapy was consisted of aerobic activity such as bicycle ergometer for 30 minutes, twice a day, five times each week for 2 weeks. The venous blood samplings were obtained on postoperative days 1, 7 and 14. NKCA was assayed by cytotoxic response against K562 cells. The venous blood samplings were obtained on postoperative days 1, 7 and 14. NKCA was assayed by cytotoxic response against K562 cells.

Results
The baseline study did not show any statistical difference between exercise group and non-exercise group. Mean NKCA of day 7 decreased in both groups compared with that at postoperative day 1 (p＜0.05). At day 14, the difference of the mean NKCA between two groups was not significant, but the mean NKCA of the exercise group without metastasis demonstrated a significant increase compared with that of the non-exercise group without metastasis (p＜0.05).

Conclusion
This study suggested that early moderate exercise had a beneficial effect on the function of NK cells in early stage of breast cancer patients after curative surgery. A further study will be needed to evaluate long-term effect of exercise on NK cell. (J Korean Acad Rehab Med 2003; 27: 250-254)