Incidence of Pathological Complete Response after Neoadjuvant Treatment in Current Vajira Hospital Rectal Cancer Practice

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Punnawat Chandrachamnong
Kullawat Bhatanaprabhabhan
Marisa Chongthanakorn
Boonchai Ngamsirimas


Background and Objective: Colorectal cancer is the third most common cancer worldwide. The current standard treatment for locally advanced rectal cancer is neoadjuvant concurrent chemoradiation therapy (CCRT) followed by total mesorectal excision (TME). The responses to CCRT differ significantly in each study, and approximately 15-30% of patients have pathological complete response(pCR). This research aims to investigate the pCR rate and the factors affecting the pCR after neoadjuvant CCRT in rectal cancer.

Method: A retrospective study of locally advanced rectal cancer, diagnosed with cT3-4, N0 or any cT, cN1-2, who underwent neoadjuvant CCRT during 2014-2020.

Results: A total of 234 rectal cancer patients, there were 101 (43.1%) patients treated with neoadjuvant CCRT, with 68 (67.3%) male patients and a mean age of 58.5 years (+/- 11.5). The most common cancer location was the lower rectum, 60 (59.4%). For clinical staging, 76 patients had cT3 (75.2%) and 54 patients had cN1-2 (53.5%). A total of 14 patients (13.9%) had pCR. When univariate analysis and multivariate analysis were calculated, it was found that CEA> 2.5, cN1-2 and capecitabine as a radiosensitizing agent affected pCR with OR 0.23 P = 0.04 (95% CI 0.59-0.93), OR 0.15 P = 0.02 (95% CI 0.03-0.79) and OR 9.89 P = 0.01 (95% CI 1.62-60.25), respectively.

Conclusion: The pCR rate was 13.9%, with factors affecting pCR were CEA> 2.5, cN1-2 and capecitabine as a radiosensitizing agent.


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Chandrachamnong P, Bhatanaprabhabhan K, Chongthanakorn M, Ngamsirimas B. Incidence of Pathological Complete Response after Neoadjuvant Treatment in Current Vajira Hospital Rectal Cancer Practice. SRIMEDJ [Internet]. 2022 Feb. 28 [cited 2023 Feb. 7];37(1):1-6. Available from:
Original Articles


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