Phosphohexose isomerase and carcinoembryonic antigen in the sera of patients with primary lung cancer

Phosphohexose isomerase (PHI) and carcinoembryonic antigen (CEA) were measured at the time of diagnosis in 300 patients with lung cancer. Serum levels were high in 75.7% and 53.0% of patients respectively. PHI levels were higher in large cell and small cell carcinomas (p less than 0.001). CEA levels were higher in adenocarcinomas (p less than 0.001). Metastatic carcinomas showed higher levels on PHI and CEA than localized cases. Survival was significantly longer in patients with normal PHI (p less than 0.001) and normal CEA (p less than 0.005) than in cases with elevated markers. The prognostic significance of PHI persisted in the different pathological types and stages, whereas CEA only had prognostic impact in non-small cell cases. Serial PHI determinations were useful for follow-up in 82.4% of cases with initial abnormal values and in 55.4% of cases with a normal value. Serial CEA was useful in 41% of cases with initially high value but in less than 15% of those with baseline normal. We conclude that PHI has prognostic significance independently of pathology and stage, whereas CEA was a prognostic indicator only in non-small cell cases; serial PHI determinations were useful more often than CEA for follow-up.