Colonoscopy and carcinoembryonic antigen variations.
BACKGROUND
Colonoscopy is essential for synchronous and metachronous cancer detection. Carcinoembryonic antigen is a colorectal cancer tumor marker, important as a follow-up tool in patients with previous colorectal cancer. False-positive carcinoembryonic antigen elevation results in multiples exams and in patient anxiety. In literature, there is reference to transient carcinoembryonic antigen increase with colonoscopy.


OBJECTIVE
To evaluate the influence of bowel preparation and colonoscopy in carcinoembryonic antigen blood levels.


METHODS
We prospectively studied subjects that underwent routine colonoscopy in our institution. Blood samples were collected (1) before bowel cleaning, (2) before colonoscopy and (3) immediately after colonoscopy. Blood carcinoembryonic antigen levels were determined by "Sandwich" immunoassay. The statistical methods used were the paired t-test and ANOVA.


RESULTS
Thirty-seven patients (22M/15F) were included; age range 28-84 (mean 56 years). Mean carcinoembryonic antigen values were 1.9, 2 and 1.8 for (1), (2) and (3), respectively. An increase in value (2) compared with (1) was observed in 20/37 patients (P = 0.018), mainly in younger patients and in patients requiring more endoluminal interventions. In 29/37 patients, the CEA value decreased from (2) to (3) (P = 1.3x10-7).


CONCLUSIONS
A trend for carcinoembryonic antigen increase after bowel cleaning was observed, especially in younger patients and in patients with more endoluminal interventions, but without clinical meaning.
Departamento de Gastroenterologia, Lisboa, Lisboa, Portugal.
Rita G
RG
Sousa
Departamento de Gastroenterologia, Lisboa, Lisboa, Portugal.
Ana
A
Nunes
Departamento de Gastroenterologia, Lisboa, Lisboa, Portugal.
Tânia
T
Meira
Departamento de Patologia Clinica, Hospital Garcia de Orta, Almada, Setúbal, Portugal.
Olga
O
Carreira
Departmento de Matemática e Centro de Matemática e Aplicações - CEMAT, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Lisboa, Portugal.
Ana M
AM
Pires
Departamento de Gastroenterologia, Lisboa, Lisboa, Portugal.
João
J
Freitas
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002272:Carcinoembryonic Antigen / Q000097:blood*; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000097:blood / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies
D002272:Carcinoembryonic Antigen