Survival Benefit for Metformin Through Better Tumor Response by Neoadjuvant Concurrent Chemoradiotherapy in Rectal Cancer

Impact of Diabetes on Pathologic Response to Multimodality Therapy for Esophageal Cancer

BACKGROUND

The incidence of esophageal cancer has increased faster than that of most cancers. Evidence from other malignant neoplasms suggests that diabetic patients have a worse response to multimodality therapy. We hypothesized that diabetic patients with esophageal cancer will have a decreased response to neoadjuvant chemotherapy and radiation therapy compared with nondiabetic patients.

METHODS

A retrospective study of The Society of Thoracic Surgeons General Thoracic Surgery Database identified all patients who had an esophagectomy after neoadjuvant therapy for esophageal cancer between 2012 and 2019. Patients were compared on the basis of the presence of diabetes. A pathologic complete response (pCR) was defined as ypT0 N0. The χ2 and Wilcoxon rank sum tests were used to compare patients' demographic and clinical characteristics between those with and those without diabetes. Multivariable logistic regression was used to evaluate the predictors of response to neoadjuvant therapy.

RESULTS

Of the 9171 patients who met inclusion criteria, 2011 (22%) patients were diabetic and 7160 (78%) patients were nondiabetic. Patients with diabetes were older, more likely to be male, and more likely to have all comorbidities. Univariate analysis revealed that diabetic patients were less likely to have pCR (16% vs 18%; P = .026). Although multivariable analysis showed a trend toward diabetic patients' having lower odds of achieving pCR, diabetes was not independently associated with pCR (odds ratio, 0.89; 95% CI, 0.78-1.01; P = .075).

CONCLUSIONS

Diabetic patients may be less likely than nondiabetic patients to achieve pCR after neoadjuvant treatment of esophageal cancer. This suggests the need for further exploration as diabetic patients with esophageal cancer can potentially benefit from different treatment paradigms compared with their nondiabetic counterparts.

Metformin increases pathological responses to rectal cancers with neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

BACKGROUND

To summarize the chemo-radio effect of metformin in rectal cancers with neoadjuvant chemoradiotherapy on pathological response, tumor regression grade (TRG), and T/N downstaging.

METHODS

PubMed, MEDLINE, Embase, and Cochrane Database of collected reviews were searched up to June 30, 2022. This study conducted systematic review and meta-analysis based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) sheet. Odds ratios (ORs) and confidence intervals (CIs) which calculated by random-effects models were displayed in forest plots. Newcastle-Ottawa scale was used to assess the risk of bias of the observational cohort studies.

RESULTS

This systematic review and meta-analysis comprised eight cohorts out of seven studies, with 2294 patients in total. We performed two-way comparison for metformin in diabetic patients vs (1) non-metformin drugs in diabetic patients and (2) nondiabetic patients. In diabetes patient studies, the metformin group had a significantly increased pathological response on TRG (OR: 3.28, CI: 2.01-5.35, I² = 0%, p < 0.001) and T downstaging (OR: 2.14, CI: 1.24-3.67, I² = 14%, p = 0.006) in comparison with a non-metformin group. When compared with nondiabetic patients, the pathological response on TRG (OR: 2.67, CI: 1.65-4.32, I² = 43%, p < 0.001) and T downstaging (OR: 1.96, CI: 1.04-3.71, I² = 66%, p = 0.04) were also higher in metformin group. The limitation was that no randomized controlled trials were available based on current literature review. Small sample sizes for diabetic metformin or non-metformin users in rectal cancer patients reduced the power of the study.

CONCLUSIONS

For patients with rectal cancer and treated with neoadjuvant chemoradiotherapy, metformin administration in diabetic patients increased the pathological response on tumor-regression grade and T downstaging. Further well-designed, high-quality randomized controlled trials are required to reveal the actual effect of metformin.

Association of Tumor Pathological Response with the Use of Metformin During Neoadjuvant Chemoradiotherapy in Rectal and Esophageal/Gastroesophageal Cancer Patients: a Systematic Review and Meta-analysis

PURPOSE

Metformin has been reported to be associated with improved cancer prognosis when used in combination with chemotherapy and/or radiotherapy. In this study, we present a systematic review and meta-analyses of studies evaluating the association of tumor pathological response with the use of metformin during neoadjuvant chemoradiotherapy (NACRT) in rectal and esophageal/gastroesophageal cancer patients.

METHODS

We systematically searched databases for articles that compared concurrent metformin use with no metformin use in cancer patients treated with NACRT following the PRISMA 2020. The design and quality of the collected studies were reviewed, and meta-analyses were performed on the pathologic complete response (pCR) rate, tumor regression grade (TRG), T factor downstaging, and N factor downstaging.

RESULTS

Three databases were searched, and 220 papers were screened. Five retrospective cohort study papers were eligible for the meta-analysis, with a total of 2041 patients. The included papers contained only rectal and esophageal/gastroesophageal cancers. In the metformin group, the pCR rate was 26% [20-32%], and metformin was associated with the pCR rate (odds ratio [OR] = 0.51 [0.34-0.76], p < 0.01). Meta-regression analysis of the pCR rate showed a positive correlation with adenocarcinoma (coefficient = 0.13 [0.02-0.25], p = 0.03) and fluoropyrimidine anticancer drug use (coefficient = 0.01 [0.001-0.02], p = 0.03).

CONCLUSIONS

The results suggest that metformin is associated with pCR rate when used in combination with NACRT. The association of metformin and pCR rate in combination with fluoropyrimidine anticancer drugs was observed mostly for adenocarcinoma patients.

Zebrafish Avatars of rectal cancer patients validate the radiosensitive effect of metformin

Neoadjuvant chemoradiation (nCRT) followed by surgery represents the standard of care in patients with locally advanced rectal cancer. Increasing radiotherapy (RT) doses and chemotherapy cycles with 5FU have been associated with increased rates of complete response, however these strategies imply significant toxicity. In the last years, epidemiologic findings have demonstrated that metformin is associated with significantly higher rates of pathological complete response to nCRT. Also, pre-clinical studies using cell lines provide evidence for the radiosensitive effect of metformin. However, no studies have been performed using rectal cancer patient samples to test this radiosensitive effect of metformin and compared it to the standard 5FU. Here, we designed an experimental study to compare both radiosensitizers in the zebrafish xenograft model (zAvatar), using rectal cancer surgical specimens and diagnostic biopsies. Patient zAvatars confirmed that metformin has indeed a powerful in vivo radiosensitizer effect, similar to 5FU. Our work confirms that metformin constitutes a promising less toxic alternative to the standard 5FU, which could be game changing in elderly/frail patients to optimize tumor regression.

The Association of Metformin, Other Antidiabetic Medications and Statins on the Prognosis of Rectal Cancer in Patients with Type 2 Diabetes: A Retrospective Cohort Study

Metformin and statin use have been associated with an improved prognosis for colorectal cancer in persons with type 2 diabetes (T2D). Data regarding rectal cancer (RC) have been inconclusive; therefore, we investigated the issue with high-quality data and a robust study design. We identified 1271 eligible patients with T2D and incident RC between 1998 and 2011 from the Diabetes in Finland (FinDM) database. Cox models were fitted for cause-specific mortality rates to obtain adjusted estimates of the hazard ratios (HR) with 95% confidence intervals (CI) in relation to use of antidiabetic medication (ADM) and statins before the RC diagnosis and for post-diagnostic use in a time-dependent exposure manner. No sufficient evidence was found for either pre- or post-diagnostic metformin use and RC mortality (HR 0.96, 95% CI 0.67–1.38, and 0.70, 95% CI 0.45–1.10, respectively) when compared to other oral ADMs. Both pre- and post-diagnostic statin use appeared to be inversely associated with mortality from RC (HR 0.77 95% CI 0.63–0.94, and 0.57, 95% CI 0.42–0.78, respectively). Our study was inconclusive as to the association of metformin use with the prognosis of RC, but statin use was found to predict reduced mortality, both from RC and from other causes of death in persons with T2D.

Statins increase pathological response in locally advanced rectal cancer treated with chemoradiation: a multicenter experience

Aims: To investigate the influence of various concomitant medications on outcomes in patients with locally advanced rectal cancer undergoing neoadjuvant chemoradiation. Materials & methods: The authors retrospectively identified 246 patients from 2003 to 2018, collecting demographic and clinicopathological data of interest. Odds ratio (OR) was used to assess the association between concomitant drugs and outcomes. Results: The authors found an association between statins and a Dworak regression grade of 3-4 (OR = 8.78; p = 0.01). Furthermore, statins were significantly associated with more frequent chemoradiation-related toxicity (OR = 2.39; p = 0.0098) and chemotherapy dose reduction or discontinuation (OR = 2.26; p = 0.03). Conclusion: Despite higher frequency of radiotherapy and chemotherapy interruption or dose reduction, the concomitant use of statins during neoadjuvant chemoradiation proved to be associated with better tumor regression.

Metformin combined with local irradiation provokes abscopal effects in a murine rectal cancer model

Although preoperative chemoradiation therapy can down-stage locally advanced rectal cancer (LARC), it has little effect on distant metastases. Metformin exerts an anti-cancer effect partly through the activation of host immunity. LuM1, a highly lung metastatic subclone of colon 26, was injected subcutaneously (sc) in BALB/c mice and treated with metformin and/or local radiation (RT). Lung metastases and the primary tumors were evaluated and the phenotypes of immune cells in the spleen and lung metastases were examined with flow cytometry and immunohistochemistry. Local RT, but not metformin, partially delayed the growth of sc tumor which was augmented with metformin. Lung metastases were unchanged in metformin or RT alone, but significantly reduced in the combined therapy. The ratios of splenic T cells tended to be low in the RT group, which were increased by the addition of metformin. IFN-γ production of the splenic CD4(+) and CD8(+) T cells was enhanced and CD49b (+) CD335(+) activated NK cells was increased after combined treatment group. Density of NK cells infiltrating in lung metastases was increased after combination treatment. Metformin effectively enhances local and abscopal effects of RT though the activation of cell-mediated immunity and might be clinically useful for LARC.

Risk factors for long-term survival in patients with ypN+ M0 rectal cancer after radical anterior resection

Background

Regional lymph node metastases are the main adverse prognostic factor in patients with rectal cancer without distant metastases. There are discrepancies, however, regarding additional risk factors in the group of ypN + M0 patients. The purpose of the study was to assess clinical and pathological factors affecting long-term oncological outcomes in the group of ypN + M0 patients after radical rectal anterior resection.

Methods

112 patients with ypN + M0 rectal cancer after neoadjuvant therapy and radical anterior resection were subject to a retrospective analysis. The effect of potential factors on survival was assessed with the use of Kaplan–Meier curves together with a log-rank test and multiple factor Cox proportional hazards model.

Results

In the multiple factor Cox analysis, adverse factors affecting disease-free survival (DFS) were: the use of angiotensin-converting enzyme inhibitors (ACEIs) (hazard ratio HR: 3.11, 95% CI 1.01–9.56, p = 0.047), presence of perineural invasion (HR: 7.27, 95% CI 2.74–19.3, p < 0.001) and occurrence of postoperative complications (HR: 6.79, 95% CI 2.09–22.11, p = 0.001), while a positive factor was the negative lymph node (NLN) count > 7 (HR: 0.33, 95% CI 0.12–0.88, p = 0.026). In the disease-specific survival (DSS) analysis, an adverse factor was the use of ACEIs (HR: 4.275, 95% CI 1.44–12.694, p = 0.009), while a positive effect was caused by NLN > 5 (HR: 0.22, 95% CI 0.082–0.586, p = 0.002).

Conclusions

The use of ACEIs may have a negative effect on long-term treatment outcomes in patients with ypN + M0 rectal cancer. In this group of patients, the NLN count seems to be an important prognostic factor, as well.

Neoadjuvant therapy of metformin is associated with good tumor response after preoperative concurrent chemoradiotherapy for rectal cancer

Metformin is associated with good tumor response in preoperative concurrent chemoradiotherapy (CCRT) for rectal cancer. This study aims to demonstrate that the timing of metformin is related to the tumor response on preoperative CCRT for rectal cancer. From January 2010 to December 2017, 232 patients who underwent curative resection after preoperative CCRT were reviewed. Patients were divided into groups with or without diabetes or metformin. The timing of metformin administration was divided based on before and from initiation of CCRT. Multivariate logistic regression analysis was used to identify predictors for tumor response. Tumor downstaging (p = 0.02) and good response rates of tumor regression grade (TRG) (p = 0.008) were significantly higher in the group administered metformin before CCRT than other groups. In the multivariate analysis, metformin administration before CCRT was a significant factor in predicting tumor downstaging [odds ratio (OR) 10.31, 95% confidence interval (CI) 1.76–102.08, p = 0.02] and good TRG (OR 12.55, 95% CI 2.38–80.24, p = 0.004). In patients with rectal cancer who underwent preoperative CCRT, neoadjuvant therapy of metformin before CCRT was significantly associated with good tumor response.

Metformin use and the risk of anal intraepithelial neoplasia in type II diabetic patients

AIM

Emerging evidence has suggested that metformin may be protective against the development of human-papillomavirus-related cancers. Anal intraepithelial neoplasia (AIN) is highly associated with human papillomavirus infection and a precancerous status of anal cancer. The aim of this study was to investigate the relationship between metformin usage and the development of AIN in a large national sample.

METHODOLOGY

The IBM MarketScan dataset was used to design a nested case-control study from 2010 to 2017. Patients aged 18-65 years with type 2 diabetes mellitus (DM) were evaluated, and cases of AIN were identified. Four controls were randomly selected in the risk set of each case by using incidence density sampling. The association between metformin usage and AIN was assessed using multivariate logistic regression modelling.

RESULTS

A total of 258 patients with type 2 DM were diagnosed with AIN during the study interval, and these were matched to 1032 control patients without a diagnosis of AIN. Patients who developed AIN had 38% lower odds of prior metformin use compared to those without a history of AIN (P < 0.01) and this finding remained robust after adjusting for age, sex, human immunodeficiency virus infection and DM complications (P = 0.02). Patients with AIN had 56% lower odds of long-term metformin use compared to control patients (P = 0.01).

CONCLUSIONS

An AIN diagnosis in patients with DM is associated with 56% lower likelihood of prior metformin use. This relationship suggests that metformin could potentially play a protective role against AIN. Prospective studies in non-diabetic patients are warranted to examine these findings further.

Is Metformin Associated With Improved Response to Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer?

Efforts to determine whether metformin can increase the effectiveness of neoadjuvant chemoradiotherapy in rectal cancer have increased in recent years. However, retrospective studies have yielded inconclusive results.

OBJECTIVES

The aim of this study was to compare oncological outcomes and survival after neoadjuvant chemoradiotherapy in patients with rectal cancer taking metformin versus in those not taking metformin.

METHODS

This study analyzed 423 consecutive patients with locally advanced rectal cancer who underwent neoadjuvant chemoradiotherapy and curative surgery between January 2010 and May 2020; of these, 59 were taking metformin and 364 were not taking metformin.

RESULTS

Patients taking metformin had a lower proportion of tumor regression (6.8% versus 22.0%, P = 0.012) as well as a lower proportion of patients achieving a pathological complete response (6.8% versus 20.6%, P = 0.011). In the multivariate analysis, independent predictors of pathologic complete response were not taking metformin (OR: 5.26, 95% CI: 1.12-24.85, P= 0.035) and cT2 stage (OR: 3.49, 95% CI: 1.10-11.07, P= 0.034); the interval was also an independent predictor of tumor regression (OR: 1.78, 95% CI: 1.06-2.96, P= 0.028). No differences were observed in survival between groups.

CONCLUSION

Metformin was not associated with better tumor responses or survival after neoadjuvant treatment.

Metformin with neoadjuvant chemoradiation to improve pathologic response in rectal cancer: A pilot phase I/II trial

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A prospective pilot phase I/II study on metformin given concurrently with neoadjuvant chemoradiation (CRT) in non-diabetic rectal cancer patients.

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Three patients had a clinical complete response (cCR) and did not have surgical resection.

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Of the 12 patients who underwent surgery, there were two pCRs. For the combined pCR/cCR rate of 33% (95% CI 19–47%), a total of 85 patients will be required to yield a 95% CI with a 10% margin of error.

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These pilot results are encouraging, and will serve to refine the design and conduct of a future phase 2 trial to determine whether adding metformin to CRT improves pCR/cCR rates.

Purpose

Neoadjuvant radiotherapy with or without chemotherapy decreases the risk of local recurrence after surgery for rectal cancer. Emerging data suggest that diabetic patients on metformin may have improved cancer outcome after radiotherapy. A single institutional pilot study was performed to determine if metformin given concurrently with long course chemoradiation (CRT) may improve pathologic complete response (pCR) in non-diabetic rectal cancer patients. The study was designed to construct a confidence interval (CI) for the pCR rate to determine the sample size for a phase 2 trial.

Methods

Non-diabetic patients with biopsy confirmed rectal cancer deemed candidates for long course neoadjuvant CRT were invited to participate. Radiation consisted of 50.4 Gy in 28 daily fractions with concurrent daily capecitabine (825 mg/m² twice daily). Participants self-administered metformin (500 mg of twice daily) 2 weeks prior to, during and for 4 weeks after CRT.

Results

A total of 16 patients were accrued. One patient withdrew from the study. Only grade 1 or 2 adverse events were observed. Three patients had a clinical complete response (cCR) and did not undergo surgery. Of the 12 patients who underwent surgery, there were two pCRs. For the combined pCR/cCR rate of 33% (95% CI 19–47%), a total of 85 patients will be required to yield a 95% CI with a 10% margin of error.

Conclusions

Adding metformin to neoadjuvant CRT for rectal cancer does not appear to enhance toxicities. These results will be used to refine the design and conduct of a future phase 2 trial to determine whether adding metformin to CRT improves pCR/cCR rates.

Effect of mistletoe extract on tumor response in neoadjuvant chemoradiotherapy for rectal cancer: a cohort study

Background

Mistletoe extract, used as a complementary chemotherapeutic agent for cancer patients, has anticancer effects against various malignancies. The aim of the present study was to evaluate the effect of mistletoe extract (Abnoba Viscum Q®) on tumor responses to neoadjuvant chemoradiotherapy (NCRT) for locally advanced rectal cancer.

Methods

This study included patients with rectal cancer who underwent NCRT between January 2018 and July 2020. In the mistletoe group (MG), the patients were administered Abnoba Viscum Q® subcutaneously during chemoradiotherapy—maintained just before surgery. Patient demographics, clinical outcomes, histopathological outcomes, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) assay results were compared between the MG and non-mistletoe group (NMG). Two rectal cancer cell lines (SNU-503 and SNU-503R80Gy) were treated with Abnoba Viscum Q® to assess its mechanistic effects in vivo.

Results

Overall, the study included 52 patients (MG: n = 15; NMG: n = 37). Baseline demographics between the two groups were similar, except carbohydrate antigen 19-9 levels and tumor location from the anal verge. There was no difference in the clinical stage between the two groups. A better tumor response in the MG, relative to the NMG, was observed with respect to tumor regression grade (TRG), T stage, and overall tumor–node–metastasis stage. Tumor response was significantly better in the MG than in the NMG in terms of pathologic complete response rate (53.3% vs. 21.6%, P = 0.044), good TRG response (66.7% vs. 32.4%, P = 0.024), T downstaging (86.7% vs. 43.2%, P = 0.004), and overall downstaging (86.7% vs. 56.8%, P = 0.040). The toxicities during NCRT were minimal in both groups. More apoptotic cells were noted in MG samples than in the NMG samples on TUNEL staining. Cleaved caspase-3 level following treatment with Abnoba Viscum Q® was higher in SNU-503R80Gy cells than in SNU-503 cells.

Conclusion

Patients treated with chemoradiation combined with mistletoe extract showed better outcomes than patients not treated with mistletoe extract in terms of tumor responses. This diversity in treatment may improve the efficacy of NCRT, leading to better oncologic outcomes. Prospective and randomized studies with long-term follow-up are warranted to confirm and extend these results.