Serum pro-gastrin-releasing peptide is a useful marker for treatment monitoring and survival in small-cell lung cancer

We investigated the usefulness of serum pro-gastrin-releasing peptide (Pro- GRP) as a tumor marker for diagnosis, treatment monitoring and the predicti on of relapse and prognosis in patients with small-cell lung cancer (SCLC). Serum samples were obtained from 127 patients with primary lung cancer (48 patients with small-cell carcinoma, 31 with adenocarcinoma, 36 with squamo us cell carcinoma and 11 with large-cell carcinoma). The cutoff levels of s erum Pro-GRP and neuron-specific enolase (NSE) were set at 46 pg/ml and 10 ng/ml, respectively. The specificity of Pro-GRP was significantly higher th an that of NSE (Pro-GRP: 93.7%, NSE: 65.8%, p < 0.01). According to the his tological type of lung cancer, the positive rates of Pro-GRP were 75% (36/4 8) in the small-cell carcinomas, 9.7% (3/31) in the adenocarcinomas, 5.6% ( 2/36) in the squamous cell carcinomas and 0% (0/10) in the large cell carci nomas. The median levels of Pro-GRP in limited disease (LD) and extensive d isease (ED) patients were 199 and 295.5 pg/ml, whereas those of NSE were 14 .8 and 29.3 ng/ml, respectively. The positive rates of Pro-GRP in LD and ED patients were 80.0% (16/20) and 71.4% (20/28), whereas those of NSE were 7 0.0% (14/20) and 89.3% (25/28), respectively. The positive rate of NSE tend ed to elevate with the progression of disease, whereas that of Pro-GRP was already high at an early stage, Among the 29 patients with SCLC who could b e followed, the serum Pro-GRP levels of 18 responders were significantly de creased after treatment (p < 0.01), whereas those of the 11 nonresponders w ere not significantly different between before and after treatment (p = 0.7 2). In the 9 patients with SCLC who relapsed, the serum Pro-GRP levels were again elevated at the time of relapse. Seventeen patients whose ratio of t he Pro-GRP level after treatment to the level before treatment was below 50 % (taking the levels before treatment as 100%) survived significantly longe r than did the patients whose ratio was over 50% (p < 0.01). The results of the present study suggest that serum Pro-GRP has high specificity and coul d be a useful marker of SCLC for treatment monitoring and prognosis.