Objective   To investigate the effect of subcutaneous or intravenous postoperative patient-controlled analgesia on T-lymphocyte subtypes and natural killer cells in patients after breast cancer surgery.  Methods   Forty female patients in our hospital

mean age 45±10

with American Society of Anesthesiologists (ASA) classificationⅠ to Ⅱ undergoing elective breast cancer surgery were randomly divided into 2 groups by the envelope method

patientcontrolled subcutaneous analgesia group (PCSA

n=20)

and patientcontrolled intravenous analgesia group (PCIA

n=20). Visual analogue scaling (VAS) were evaluated at 6

12

18

24 and 48 h after operation respectively. Blood samples were collected before anesthesia (T1)

at the end of surgery (T2) and 1 (T3)

2 (T4)

and 5 d (T5) after surgery to measure Tlymphocyte subsets (CD3+

CD4+

CD8+

CD4+/CD8+ and CD45+) and NK cells by flow cytometry.  Results  VAS scores was lower than 3 in both groups

and there was no any difference between them (P0.05). Compared with baseline

the levels of CD3+

CD4+ and CD8+ were decreased significantly at T3

T4 and T5 in both groups. (P0.01). The level of NK cells was decreased significantly at T4 in PCSA group (P0.05) and at T3 and T4 in PCIA group (P0.01). CD4+/CD8+ratio was decreased significantly at T2 and increased significantly at T3 in PCIA group (P0.05)

but the ratio was increased significantly at T4 and T5 in PCSA group (P0.05). The level of CD4+ in PCSA group and the CD4+/CD8+ ratio in PCIA group were decreased significantly at T2 (P0.05). There was no significant difference in CD3+

CD4+

CD8+

CD4+/CD8+

CD45+and NK cells in both groups at anytime points after operation (P0.05).  Conclusion  PCSA and PCIA are excellent  Methods   for analgesia in patients after breast cancer surgery

and they have the same effects on the immune system.