CEA and CA 19-9 measurement as a monitoring parameter in metastatic colorectal cancer (CRC) under palliative first-line chemotherapy with weekly 24-hour infusion of high-dose 5-fluorouracil (5-FU) and folinic acid (FA)

Background: There have been contradictory reports on the benefit of CEA and CA 19-9 measurements in patients with metastatic colorectal cancer using p alliative chemotherapy. The object of this study was to examine the diagnos tic accuracy of monitoring of palliative chemotherapy by means of CEA and C A 19-9. Patients and methods: The tumour markers CEA and CA 19-9 were subjected to serial measurement in patients with metastatic colorectal cancer (n = 90) u sing palliative first-line chemotherapy with weekly 24-hour infusion of hig h-dose 5-FU with FA and were compared with objective response according to WHO criteria. 85 patients could be evaluated. 43 patients (51%) initially h ad elevated CEA (greater than or equal to 10 ng/ml) and 33 patients (39%) e levated CA 19-9 (greater than or equal to 50 IE/ml). In 24 patients (28%), both markers were initially increased. With CEA positive patients, 143 cycl es of chemotherapy were carried out, which showed the following response in the various cycles: 21 episodes with progressions (ePD), 69 episodes with no change (eNC), 53 episodes with partial/complete remission (ePR/eCR). Wit h CA 19-9 positive patients, 100 cycles of chemotherapy were carried out wi th the following results: 21 episodes with progressions (ePD), 48 episodes with eNC, and 31 episodes with ePR/eCR. Results: A CEA rise by at least 50% differentiated between ePD versus eNC/e PR/eCR with a sensitivity of 76% and specificity of 90%. With CEA decreases of at least 30% in 99% of these patient episodes (78 of 79), a tumour prog ression could be excluded. Patients with an initial drop in CEA after the f irst cycle of chemotherapy of at least 50% of the initial level had a signi ficantly higher probability of achieving an ePR/eCR in further therapy (rel ative risk 2.9; P = 0.002). With an CA 19-9 increase of at least 30%, a sen sitivity progression of 62% and a specifity of 90% could be calculated. A C A 19-9 decrease of at least 60% excludes a progression in 95% of the patien t episodes. Conclusions: A CEA or CA 19-9 rise is only conditionally appropriate for re cording progressions. A progression however, can be excluded with falling l evels with high diagnostic accuracy, in which CEA offers a greater degree o f certainty than CA 19-9. With a drop in CEA 79 of 143 (= 55%) of the CT sc ans could be saved, in which case 78 of 79 patient episodes (99%) were corr ectly assessed as 'no progression'. In patients with an increased CEA and C A 19-9 the CEA determination is sufficient for the further monitoring. A co nfirmation of these results by multicenter trials can result in a considera ble decrease of monitoring costs for palliative treatment.