Does CEA decrease after radical treatment of unresectable rectal cancer predicts the outcome?
PO-1095
Abstract
Does CEA decrease after radical treatment of unresectable rectal cancer predicts the outcome?
Authors: Kraszkiewicz|, Malgorzata(1)*[jump81@wp.pl];Napieralska|, Aleksandra(1);Miszczyk|, Leszek(1);Majewski|, Wojciech(1);
(1)Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Radiotherapy Department, Gliwice, Poland;
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Purpose or Objective
To evaluate how post-treatment carcinoembryonic antigen (CEA) serum concentration decrease corresponds with the outcome of definitive radiotherapy (RT) or radiochemotherapy (RT-CHT) in primary unresectable rectal cancer patients (pts).
Material and Methods
Inclusion criteria of this retrospective study were: primary unresectable, locally advanced rectal cancer with histopathological confirmation, RT/RT-CHT as radical treatment and measured CEA post-treatment level.
Between 2000 and 2016 145 pts were treated due to unresectable rectal cancer. The aim of the treatment was tumour downsizing allowing further radical surgery.
Among them, 71 had pre- and post-treatment CEA and 10 post-treatment CEA measurements, therefore the group of 81 pts (60 men, 21 women) was evaluated in this study. Out of 81 pts: 33 (41%) received RT (accelerated hyperfractionation: 66 Gy in 1.5 Gy fx, twice a day or conventional fractionation 60-66 Gy in 2 Gy fx) and 48 (59%) RT-CHT (54 Gy/1.8 Gy fx +2 cycles of 5-Fu LV).
Six to eight weeks after RT or RT-CHT tumor resectability was evaluated again using physical examination and imaging studies.
Pts were divided in two groups. (group A): pts with CEA post-treatment decrease or below 5 ng/ml and (group B): pts without post-treatment decrease of CEA or level above 5 ng/ml.
Statistical test used were Kaplan-Meyer survival analysis, log rank test and Cox regression model.
Results
Median follow-up after the end of RT/ RT-CHT was 5.5 years. Fifty four pts (67%) had radical resection after neoadjuvant RT/RT-CHT and 27 (33%) were still unresectable.
CEA serum concentration decrease or level below 5ng/ml (group A) was observed in 63 pts (77%), CEA serum concentration increase/level above 5ng/ml (group B) in 18 (22%).
In univariate analysis pts in group A had better overall survival compared to group B (p=0.039, median OS of 40 months vs 87 months, respectively).
Five-year OS was 62% in group A compared to 30% in group B. Moreover, pts who received RT-CHT had better 5-year OS compared to RT (63 vs 44%) respectively (p=0.04).
Pts after radical resection had better 5-year OS than those still uresectable (71% vs 21%, p=0,000).
Significant factors were then checked in multivariate analysis. Only radical surgery had reached statistical significance (p=0,000) for OS.
Conclusion
Pts with post-treatment serum CEA concentration decrease or level below 5 ng/ml tend to have better overall survival compared to those in whom CEA concentration did not decrease after the neoadjuvant treatment.
Post-treatment decrease in serum CEA concentration in primary unresectable rectal cancer patients who received definitive RT/RT-CHT can be a useful predictor of outcome. Analysis on larger group of pts is needed to evaluate these results.