Clinical significance of adjuvant chemotherapy for pathological complete response rectal cancer patients with acellular mucin pools after neoadjuvant chemoradiotherapy

Mian Chen; Jianwei Zhang; Yujie Hou; Huashan Liu; Xinjuan Fan; Shuangling Luo; Zhanzhen Liu; Huanxin Hu; Sicong Lai; Liang Kang; Liang Huang

doi:10.1177/17562848221117875

Clinical significance of adjuvant chemotherapy for pathological complete response rectal cancer patients with acellular mucin pools after neoadjuvant chemoradiotherapy

Therap Adv Gastroenterol. 2023 Feb 3:16:17562848221117875. doi: 10.1177/17562848221117875. eCollection 2023.

Authors

Mian Chen^{1

2

3}, Jianwei Zhang^{3

4}, Yujie Hou^{1

2

3}, Huashan Liu^{1

2

3}, Xinjuan Fan^{3

5}, Shuangling Luo^{1

2

3}, Zhanzhen Liu^{1

2

3}, Huanxin Hu^{1

2

3}, Sicong Lai^{1

2

3}, Liang Kang⁶, Liang Huang⁶

Affiliations

¹ Department of Colorectal Surgery, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
² Guangdong Institute of Gastroenterology, Guangzhou, Guangdong, China.
³ Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
⁴ Department of Medical Oncology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
⁵ Department of Pathology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
⁶ Department of Colorectal Surgery, Guangdong Institute of Gastroenterology, and Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong 510655, China.

Abstract

Background: Approximately 15-30% of locally advanced rectal cancer (LARC) patients achieved pathological complete response (pCR) after neoadjuvant chemoradiotherapy (CRT) and total mesorectal excision, but the clinical significance of adjuvant chemotherapy (ACT) for pCR patients remains unclear.

Objectives: To determine whether LARC pCR patients can benefit from the administration of ACT.

Design: Single center retrospective study.

Methods: This study retrospectively included 280 LARC patients who achieved pCR after CRT and surgery from 2011 to 2019. The information of patients was recorded. Main outcome measures included 5-year disease-free survival (DFS) and 5-year overall survival. Subgroup analysis was conducted on whether pCR patients with acellular mucin pools received ACT or not.

Results: A total of 74/280 (26.4%) patients were identified with acellular mucin pools. Disease recurrence occurred in 38/280 (13.6%) patients, and in the subgroup of patients with acellular mucin pools, 15/74 (20.3%) patients developed distant metastases. The existence of acellular mucin pools was associated with worse DFS (79.7% versus 88.8%, P = 0.037). Among pCR patients with acellular mucin pools, 9/25 (36.0%) of non-ACT patients occurred recurrence, and ACT was beneficial for improving DFS (hazard ratio: 0.245; 95% confidence interval: 0.084-0.719; P = 0.010).

Conclusions: The existence of acellular mucin pools may represent a sign of invasive tumor biology, which indicated a negative prognosis. ACT can improve the prognosis of patient with acellular mucin pools, so ACT should be considered for them.

Keywords: acellular mucin pools; adjuvant chemotherapy; pathological complete response.