Complete response after neoadjuvant treatment for rectal cancer

TXN inhibitor impedes radioresistance of colorectal cancer cells with decreased ALDH1L2 expression via TXN/NF-κB signaling pathway

Background

Colorectal cancer (CRC) is prevalent worldwide and is often challenged by treatment failure and recurrence due to resistance to radiotherapy. Here, we aimed to identify the elusive underlying molecular mechanisms of radioresistance in CRC.

Methods

Weighted gene co-expression network analysis was used to identify potential radiation-related genes. Colony formation and comet assays and multi-target single-hit survival and xenograft animal models were used to validate the results obtained from the bioinformatic analysis. Immunohistochemistry was performed to examine the clinical characteristics of ALDH1L2. Co-immunoprecipitation, immunofluorescence and flow cytometry were used to understand the molecular mechanisms underlying radioresistance.

Results

Bioinformatic analysis, in vitro, and in vivo experiments revealed that ALDH1L2 is a radiation-related gene, and a decrease in its expression induces radioresistance in CRC cells by inhibiting ROS-mediated apoptosis. Patients with low ALDH1L2 expression exhibit resistance to radiotherapy. Mechanistically, ALDH1L2 interacts with thioredoxin (TXN) and regulates the downstream NF-κB signaling pathway. PX-12, the TXN inhibitor, overcomes radioresistance due to decreased ALDH1L2.

Conclusions

Our results provide valuable insights into the potential role of ALDH1L2 in CRC radiotherapy. We propose that the simultaneous application of TXN inhibitors and radiotherapy would significantly ameliorate the clinical outcomes of patients with CRC having low ALDH1L2.

Pathological Complete Response After Neoadjuvant Therapy in Rectal Adenocarcinoma: a 5-Year Follow-up

Neoadjuvant therapy is the gold standard treatment of locally advanced rectal cancer. It may induce complete sterilization of tumor cell and decreases its local recurrence rate. While 15–20% of patients were found to have pathological complete response (pCR) with combined multimodal therapy, Asian data were generally scarce. pCR rate can indicate the suitability of applying the “watch-and-wait” strategy, which advocates deferment of surgery that can alleviate surgery-associated morbidity.To determine the percentage of pCR of rectal cancer after neoadjuvant therapy. Patients diagnosed with rectal cancer underwent treatment from 2013 to 2017 were retrieved retrospectively. Demographic data, tumor localization, pre- and post-operative pathological reports, neoadjuvant therapy, and pCR status were collected from patients’ records. A total of 242 out of 259 patients were treated with definitive rectal surgery. Mean age was 67.1 years old. Chinese ethnicity and male gender were predominant (n = 131, 54.1% and n = 146, 64.3% respectively). More than half (n = 124, 51.2%) had tumor located at mid or low rectum. Histologically, moderate differentiated adenocarcinoma was predominant (n = 227, 93.8%). Merely half (n = 123, 50.8%) of the patients received neoadjuvant chemoradiation therapy, but only 12 (9.8%) had a pCR. From follow-up on these 12 pCR patients, most had 2-year disease-free survival but 1 (8.3%) of the pCR had distant metastasis within 1-year post-surgery. The pathological complete response rate in our center was lower than reported. Stringent patient selection with close follow-up for patients should be carried out if the “watch-and-wait” strategy is implemented in our population.

Transanal versus nontransanal surgery for the treatment of primary rectal gastrointestinal stromal tumors: a 10-year experience in a high-volume center

Background

Rectal gastrointestinal stromal tumor (GIST) is a rare digestive disease that has a distinct malignant tendency compared to that of gastric-derived GIST. At present, there is still no standard, and the surgical approach to rectal GIST is controversial.

Methods

The clinicopathological data and prognosis of rectal GIST patients admitted to the Sixth Affiliated Hospital of Sun Yat-sen University from 1998.01.01 to 2018.12.31 were collected retrospectively. All cases were divided into either the transanal (TA) group or the nontransanal (NTA) group.

Results

A total of 537 GIST cases were treated in 10 years, including 82 rectal GIST cases (64 cases underwent surgical resection, including 29 cases in the TA group and 35 cases in the NTA group). Preoperative neoadjuvant therapy (P=0.003), postoperative adjuvant therapy (P=0.017), operative time (P=0.013), blood loss (P=0.038), anus-preserver (P=0.048), 30-day complication rate (P=0.000), time to flatus (P=0.036), hospital stays (P=0.011), distance from the anus (P=0.047), tumor size (P=0.002), mitotic count (P=0.035) and National Institutes of Health (NIH) criteria (P=0.000) were significantly different between these two groups (all P<0.05). The median follow-up time was 41 (range, 1–122) months. Twelve patients had recurrence and metastasis, and 4 patients died. The 5-year disease-free survival (DFS) and overall survival (OS) were 74.4% and 91.2%, respectively, in the whole group. There were no statistically significant differences between the TA group and the NTA group at 5-year DFS (81.3% vs. 79.0%, P=0.243) and OS (88.7% vs. 93.3%, P=0.308).

Conclusions

In the treatment of rectal GIST, TA resection has a minimally invasive effect, less postoperative complications, high anal sphincter preservation rate, and R0 resection rate and a better prognosis. How to improve the proportion of neoadjuvant therapy and choose the appropriate cases for TA surgery is still a challenge.