Comparing the histological groups we found significantly lower circulating survivin levels in patients with SqCC (0/0–171.24/pg/ml) than in patients with ADC (24.94/0–626.46 pg/ml) or SCLC (45.51/0–829.74/pg/ml) (ADC vs. SqCC p < 0.0001, ADC vs. SCLC p = 0.0405, SqCC vs. SCLC p < 0.0001). This evidence concerns the gene BIRC5 and AIDS dementia complex.