The impact of extended waiting time on tumor regression after neoadjuvant chemoradiotherapy for locally advanced rectal cancer / 中华外科杂志

Objective: To investigate the influence of extending the waiting time on tumor regression after neoadjuvant chemoradiology (nCRT) in patients with locally advanced rectal cancer (LARC). Methods: Clinicopathological data from 728 LARC patients who completed nCRT treatment at the First Affiliated Hospital, Naval Medical University from January 2012 to December 2021 were collected for retrospective analysis. The primary research endpoint was the sustained complete response (SCR). There were 498 males and 230 females, with an age (M(IQR)) of 58 (15) years (range: 22 to 89 years). Logistic regression models were used to explore whether waiting time was an independent factor affecting SCR. Curve fitting was used to represent the relationship between the cumulative occurrence rate of SCR and the waiting time. The patients were divided into a conventional waiting time group (4 to <12 weeks, n=581) and an extended waiting time group (12 to<20 weeks, n=147). Comparisons regarding tumor regression, organ preservation, and surgical conditions between the two groups were made using the t test, Wilcoxon rank sum test, or χ2 test as appropriate. The Log-rank test was used to elucidate the survival discrepancies between the two groups. Results: The SCR rate of all patients was 21.6% (157/728). The waiting time was an independent influencing factor for SCR, with each additional day corresponding to an OR value of 1.010 (95%CI: 1.001 to 1.020, P=0.031). The cumulative rate of SCR occurrence gradually increased with the extension of waiting time, with the fastest increase between the 9th to <10th week. The SCR rate in the extended waiting time group was higher (27.9%(41/147) vs. 20.0%(116/581), χ2=3.901, P=0.048), and the organ preservation rate during the follow-up period was higher (21.1%(31/147) vs. 10.7%(62/581), χ2=10.510, P=0.001). The 3-year local recurrence/regrowth-free survival rates were 94.0% and 91.1%, the 3-year disease-free survival rates were 76.6% and 75.4%, and the 3-year overall survival rates were 95.6% and 92.2% for the conventional and extended waiting time groups, respectively, with no statistical differences in local recurrence/regrowth-free survival, disease-free survival and overall survival between the two groups (χ2=1.878, P=0.171; χ2=0.078, P=0.780; χ2=1.265, P=0.261). Conclusions: An extended waiting time is conducive to tumor regression, and extending the waiting time to 12 to <20 weeks after nCRT can improve the SCR rate and organ preservation rate, without increasing the difficulty of surgery or altering the oncological outcomes of patients.

Surgical treatment strategies for locally advanced rectal cancer after neoadjuvant radiation / 中华胃肠外科杂志

For locally advanced rectal cancer after neoadjuvant radiation, it is difficult to make a choice between close observation, local resection, and radical resection. The decision should be made after carefully weighing postoperative complications, anal function, local recurrence and long-term survival. There is a high consistency of the radiosensitivity between primary tumor and mesenteric lymph node, which may be used to guide the treatment decisions. If the primary tumor shrinks significantly after neoadjuvant radiation, local resection is recommended, and the next treatment plan should be made based on the pathological examination of resected specimen. Transabdominal radical resection is recommended for unfavorable tumors. Distal resection margin should be at least 1 cm, and marking the inferior margin of tumor is also recommended before neoadjuvant radiation since it would shrink significantly after radiation.

Association of epithermal growth factor receptor expression and its downstream gene mutation status with radiosensitivity of colorectal carcinoma cell lines in vitro / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of epithermal growth factor receptor (EGFR) expression and K-ras, B-raf and PIK3CA mutation status on the radiosensitivity of human colorectal carcinoma (CRC) cell lines in vitro.</p><p><b>METHODS</b>Real-time RT-PCR was used to measure EGFR mRNA expression in nine human CRC cell lines, and K-ras, B-raf and PIK3CA mutation status of each CRC cell line was also identified respectively. After treatment with irradiation at graded dose, the cell viability was measured by clonogenic survival assay. The rate of cell apoptosis and cell cycle distribution were tested by flow cytometry. The cell morphology was observed with hoechst 33258 staining to analyze the correlation between EGFR mRNA expression and radiosensitivity of CRC cell lines.</p><p><b>RESULTS</b>A positive correlation between EGFR mRNA expression and survival fraction of 2 Gy(SF2) was observed (r=0.717, P=0.030). Association was also identified between the mutation status of PIK3CA and radiosensitivity (t=2.401, P=0.047), while mutation status of K-ras and B-raf was not associated with radiosensitivity. At 48-hour after exposing to irradiation, the apoptosis rate of radiosensitive cell line (HCT116) was significantly increased in a dose-dependent manner (P<0.05), while the apoptosis rate of radioresistant cell line (HT29) was significantly increased only when radiation dose increased to 6 Gy. The ratio of G0/G1 phase was reduced significantly with the increase of radiation dose in radiosensitive cell line (HCT116, P<0.05), while this trend was not observed in radioresistant cell line (HT29, P>0.05).</p><p><b>CONCLUSIONS</b>Over-expression of EGFR mRNA is correlated to radioresistance of human CRC cell lines, and mutation status of PIK3CA is closely related with radiosensitivity of CRC cells. The inhibition of apoptosis and G0/G1 arrest may induce the radioresistance of CRC cell lines.</p>

Competing endogenous RNA regulation mechanism and its role in the development and progression of colorectal cancer / 中华胃肠外科杂志

MicroRNAs are negative regulators of mRNA, and latest studies show that "mRNAs can also inhibit microRNAs". With these reciprocal interactions, different mRNAs with identical "microRNA binding site" cim regulate each other by competitively binding to the same microRNA pool. This is the novel competing endogenous RNA (ceRN A)regulating mechanism. The ceRN A mechanism, which is a totally new regulating mechanism , greatly expands the regulatory network across genes. It has been proved by experimental evidence that, in HCT116 colon cancer cells,KRAS and PTEN , ZEB2 and PTEN can regulate each other by ceRNA mechanism.

Management of colorectal high-grade intraepithelial neoplasia based on colonoscopic biopsy / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the principle of management of colorectal high-grade intraepithelial neoplasia(HGIN) based on colonoscopic biopsy.</p><p><b>METHODS</b>Patients diagnosed as colorectal HGIN based on colonoscopic biopsy in the Changhai Hospital from January 2002 to December 2009 were enrolled in the study. The clinical data of all the patients were collected and analyzed. According to the subsequent operation, cases were divided into local complete resection group and radical operation group. The discrepancy between the biopsy diagnosis and postoperative diagnosis was investigated.</p><p><b>RESULTS</b>Of the 203 biopsy-based colorectal HGIN lesions, 156 underwent radical resection, while 47 received local complete resection. Univariate analyses indicated that tumors located in colon(P=0.02), tumors with sessile growth (P=0.00) and large tumors (P=0.00) were more likely to be treated with radical resection. Postoperative diagnosis revealed that 163 cases(80.3%) were invasive cancers, while the other 40 cases(19.7%) were HGIN lesions. Of the 156 cases resected radically, 140 cases were invasive cancers, 16 cases were diagnosed as HGIN. Of the 47 cases who underwent local complete resection, 24 cases were confirmed as HGIN but the other 23 cases were invasive cancers, in which 15 cases received subsequent radical operation.</p><p><b>CONCLUSIONS</b>A large proportion of biopsy-proven colorectal HGIN lesions are invasive cancers. Therefore, local resection should be performed to confirm diagnosis. For highly suspected malignant tumors which can not be removed completely by local resection, if anus can be reserved, a radical transabdominal surgery is recommended even without biopsy-proven malignancy in order to avoid treatment delay.</p>

Down regulation of multidrug resistance-associated protein 4 expression by RNA interference enhances radiosensitivity of colorectal carcinoma cell lines in vitro / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of multidrug resistance-associated protein 4 (MRP4) expression on the radiosensitivity of colorectal carcinoma cell lines in vitro.</p><p><b>METHODS</b>The vector of shRNA for RNA interference was constructed and then transfected into HCT116 cell line to steadily down-regulate the expression of MRP4. HCT116 cells were divided into 3 groups including the CON group(non-transfected), NC group (negative control virus was added), and KD group (RNAi target was added for transfection). To test the effectiveness of RNA interference, real-time polymerase chain reaction and Western blot were used to measure the expression pattern of MRP4 at both mRNA and protein levels, respectively. For the examination of the effect of RNA interference of MRP4 on the radiosensitivity, flow cytometry was used to calculate the rate of apoptotic cells 24 h after 4 Gy radiation. Proliferation of the cells was measured via MTT assay at different time points.</p><p><b>RESULTS</b>ShRNA plasmid was successfully constructed. Transfection of this constructed vector into HCT116 cell line caused steady silencing of MRP4 expression (HCT116-KD). MRP4 mRNA and protein expression were significantly down-regulated following RNA interference(P<0.05). Twenty-four hours after radiation, the apoptosis rate of KD cell line was (71.7±0.8)%, significantly higher than that in the CON group [(56.1±0.9)%] and NC group[(59.8±0.8)%](P<0.05). Fourty-eight hours and 72 hours after radiation, the proliferation was significantly inhibited in KD cells compared to the control groups(P<0.05).</p><p><b>CONCLUSIONS</b>Expression of MRP4 is closely related to radio-tolerance of colorectal carcinoma. Down-regulation of MRP4 expression by RNA interference enhances radiosensitivity of colorectal carcinoma cell lines in vitro. MRP4 may be an effective molecular marker for predicting the radiosensitivity of colorectal carcinoma.</p>

Long non-coding RNA influences radiosensitivity of colorectal carcinoma cell lines by regulating cyclin D1 expression / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To screen long non-coding RNA which influences radiosensitivity of colorectal carcinoma cell lines and investigate the mechanism.</p><p><b>METHODS</b>Under different doses of radiation, colony formation assay and single-hit multi-target model were conducted to draw dose-survival curve and SF2 value of colorectal carcinoma cell lines(RKO, Lovo) was calculated. High-throughput lncRNA/mRNA chips were used to screen lncRNA genes and protein coding genes with expression differences more than 2 folds between RKO, Lovo cell lines and RKO cell line receiving 2Gy radiation. The main action pathway was computed by Gene Ontology analysis combined with Pathway analysis in order to explore the mechanism which induces the effect of lncRNA on radiosensitivity of colorectal carcinoma cell lines. Further experiment on P53, P21, cyclin D1 expression contents of RKO cell line was confirmed by real-time RT-PCR.</p><p><b>RESULTS</b>Lovo(SF2=0.47) was more sensitivity to radiation than RKO(SF2=0.53) according to the outcome of colony formation assay. High-throughput lncRNA/mRNA chips identified a total of 268 lncRNA genes and 270 protein coding genes. Gene Ontology analysis showed that the expression of genes associated with cell cycle process were significantly different (38.6%). There was a significant relationship between expression of several lncRNAs and CCND1 gene. Real-time RT-PCR showed no significant differences of P53 and P21 expression in RKO and Lovo cell lines(P>0.05), while cyclin D1 expression of RKO cell line was higher than that of Lovo cell lines(P<0.05). After exposed to 2 Gy doses of radiation, there was an obvious decrease of cyclin D1 expression in RKO cell lines(P<0.05), while P53 and P21 expressions were not different(P>0.05).</p><p><b>CONCLUSION</b>The possible mechanism is that lncRNAs compose transcription compound to combine with CCND1 gene and influence radiosensitivity of colorectal carcinoma cell lines by regulating expression of cyclin D1, which is independent of P53-P21-cyclin D1 pathway.</p>

Impacts of preoperative radiochemotherapy on operation and postoperative complications in patients with mid-low rectal carcinomas / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the impact of preoperative radiochemotherapy on postoperative complications in patients with mid-low rectal carcinomas.</p><p><b>METHODS</b>Clinicopathologic data of T3 and T4 patients with mid-low rectal carcinomas in the Department of Colorectal Surgery at the Changhai Hospital of The Second Military Medical University from January 2009 to December 2010 were analyzed retrospectively. This cohort included 81 patients treated with preoperative radiochemotherapy followed by operation(radiochemotherapy group) and 93 cases who underwent surgery alone(control group).</p><p><b>RESULTS</b>Both resection rate and sphincter preservation rate were higher in the radiochemotherapy group(100% and 86.4%) than those in the control group(94.6% and 73.1%), and the difference in sphincter preservation rate was statistically significant(P=0.039). There were no significant differences in the mean operative time [(130±15) min vs.(125±20) min, P>0.05] and mean amount of bleeding [(100±15) ml vs. (95±10) ml, P>0.05] between the two groups. The overall incidence of postoperative complications was similar(9.9% vs. 9.7%, P>0.05).</p><p><b>CONCLUSIONS</b>Preoperative radiochemotherapy can significantly increase sphincter preservation rate of mid-low rectal carcinomas, and does not increase the difficulty in surgical procedure and postoperative complications.</p>