Is primary tumor resection associated with a longer survival in colon cancer and unresectable synchronous metastases? A 4-year multicentre experience

Primary tumor resection for asymptomatic colorectal cancer patients with synchronous unresectable metastases: a meta-analysis of randomized controlled trials and case-matched studies

PURPOSE

The value of upfront primary tumor resection (PTR) for asymptomatic unresectable metastatic colorectal cancer (mCRC) patients remains contentious. This meta-analysis aimed to assess the prognostic significance of upfront PTR for asymptomatic unresectable mCRC.

METHODS

A systematic literature search was performed on June 21st, 2024. To minimize the bias and ensure robust evidence, only randomized controlled trials (RCTs) and case-matched studies (CMS) that compared PTR followed by chemotherapy to chemotherapy alone were included. The primary outcome was overall survival (OS), while cancer-specific survival (CSS) served as the secondary outcome.

RESULTS

Eight studies (three RCTs and five CMS) involving 1221 patients were included. Compared to chemotherapy alone, upfront PTR followed by chemotherapy did not improve OS (hazard ratios [HR] 0.91, 95% confidence interval [CI] 0.79-1.04, P = 0.17), but was associated with slightly better CSS (HR 0.59, 95% CI 0.40-0.88, P = 0.009).

CONCLUSIONS

The current limited evidence indicates that upfront PTR does not improve OS but may enhance CSS in asymptomatic unresectable mCRC patients. Ongoing trials are expected to provide more reliable evidence on this issue.

Survival Benefit of Primary Tumor Resection Combined With Chemotherapy in Patients With Unresectable Colorectal Mucinous Adenocarcinoma With Liver Metastasis

OBJECTIVE

To evaluate the survival benefit of combining primary tumor resection (PTR) and chemotherapy in patients with unresectable colorectal mucinous adenocarcinoma with liver metastasis (UCR-MAC-LM).

METHODS

We obtained data from the surveillance, epidemiology, and end results database for patients with UCR-MAC-LM from 2010 to 2017. Clinicopathological characteristics were analyzed using the χ2 test. Propensity score matching was performed to balance baseline characteristics. Kaplan-Meier analysis and log-rank tests were used to estimate and compare survival outcomes. Univariate and multivariate Cox regression analyses were conducted to identify the prognostic factors.

RESULTS

A total of 10,178 patients with unresectable colorectal adenocarcinoma with liver metastasis were included, of whom 6.01% (n=612) had UCR-MAC-LM. The UCR-MAC-LM group had a higher proportion of female patients, a greater number of elderly patients, an increased incidence of right colon localization, larger tumor size, and higher T and N staging than the unresectable colorectal non-mucinous adenocarcinoma with liver metastasis group (P<0.05). Multivariate analysis identified several independent prognostic factors (P<0.05). Patients with unresectable colorectal adenocarcinoma with liver metastasis who underwent PTR+C had superior survival rates compared with those who received PTR/C alone or no treatment (cancer-specific survival, P<0.05; overall survival, P<0.05). Subgroup analysis revealed that 17 of 22 groups of patients with UCR-MAC-LM who received PTR+C had significantly prolonged long-term survival compared with those who received PTR/C alone.

CONCLUSIONS

This surveillance, epidemiology, and end results-based study indicates that PTR+C may offer a survival advantage for a specific subgroup of patients with UCR-MAC-LM compared with PTR/C alone. Nonetheless, additional clinical trials are necessary to validate these findings.

The impact of primary tumor resection for asymptomatic colorectal cancer patients with unresectable metastases: a systematic review and meta-analysis

BACKGROUND

Whether patients with asymptomatic primary tumors and unresectable metastases of colorectal cancer (CRC) should undergo primary tumor resection (PTR) remains controversial. This study aims to determine the appropriateness of PTR for these individuals by evaluating a number of outcome measures.

METHODS

A systematic literature search was performed. Outcome measures included overall survival, emergency surgery rates, incidence of postoperative complications, time to initiate chemotherapy, conversion rates, and chemotherapy-related toxicities.

RESULTS

Patients who received PTR in addition to chemotherapy had a better overall survival rate than those who only received chemotherapy (HR = 0.62, 95%CI, 0.50-0.78, I2 = 84%, p < 0.00001). In the RCT subgroup, there were no significant differences with a HR of 0.72 (95%CI, 0.45-1.13, I2 = 17%, p = 0.15). More patients in the chemotherapy alone group could be converted to resectable status (OR = 0.47, 95%CI, 0.27-0.82, I2 = 0%, p = 0.008), but the incidence of emergency surgery was 23% (95%CI, 17-29%, I2 = 14%). The risk of chemotherapy-related toxicity was not significantly higher in the PTR group (OR = 1.5, 95%CI, 0.94-2.43, p = 0.09, I2 = 0%), with a 7% incidence of postoperative complications (95%CI, 0-14%, p = 0.05, I2 = 0%). The time to initiate chemotherapy after PTR was approximately 33.06 days (95%CI, 25.55-40.58, I2 = 0%).

CONCLUSION

PTR plus chemotherapy may be associated with improved survival in asymptomatic CRC patients with unresectable metastases. However, PTR did not provide a significant survival benefit in the subgroup of RCTs. Additionally, PTR did not result in a significantly increased risk of chemotherapy-related toxicity, with a postoperative complication rate of approximately 7%, and chemotherapy could be initiated at approximately 33.06 days after PTR. Compared with the PTR plus chemotherapy, chemotherapy alone could result in a significantly higher conversion rate. However, about 23% of patients receiving chemotherapy alone required emergency surgery for primary tumor-related symptoms. The above results needed to be validated in future larger prospective randomized trials.

Survival outcomes for patients with colorectal cancer with synchronous liver only metastasis

BACKGROUND

Colorectal cancer with synchronous liver-only metastasis is managed with a multimodal approach, however, optimal sequencing of modalities remains unclear.

METHODS

A retrospective review of all consecutive rectal or colon cancer cases with synchronous liver-only metastasis was conducted from the South Australian Colorectal Cancer Registry from 2006 to 2021. This study aimed to investigate how order and type of treatment modality affects overall survival.

RESULTS

Data of over 5000 cases were analysed (n = 5244), 1420 cases had liver-only metastasis. There were a greater number of colon than rectal primaries (N = 1056 versus 364). Colonic resection was the preferred initial treatment for the colon cohort (60%). In the rectal cohort, 30% had upfront resection followed by 27% that had chemo-radiotherapy as 1st line therapy. For the colon cohort, there was an improved 5-year survival with surgical resection as initial treatment compared to chemotherapy (25% versus 9%, P < 0.001). In the rectal cohort, chemo-radiotherapy as the initial treatment was associated with an improved 5-year survival compared to surgery or chemotherapy (40% versus 26% versus 19%, P = 0.0015). Patients who were able to have liver resection had improved survival, with 50% surviving over 5 years compared to 12 months in the non-resected group (P < 0.001). Primary rectal KRAS wildtype patients who underwent liver resection and received Cetuximab had significantly worse outcomes compared to KRAS wildtype patients who did not (P = 0.0007).

CONCLUSIONS

Where surgery is possible, resection of liver metastasis and primary tumour improved overall survival. Further research is required on the use of targeted treatments in patients undergoing liver resection.

Impact of Upfront Chemotherapy on the Effect of Primary Tumour Resection for Asymptomatic Synchronous Colorectal Cancer With Unresectable Metastases: A Propensity-Score-Matched Cohort Analysis

Background:

It is controversial whether primary tumour resection (PTR) and the sequencing of chemotherapy and PTR are associated with the survival of patients with incurable stage IV colorectal cancer. This study aimed to explore the effects of PTR and the sequencing of chemotherapy and PTR on asymptomatic colorectal cancer with synchronous unresectable metastases (asmCRC).

Patients and Methods:

Patients with asmCRC were retrospectively identified from a single centre and categorised into 3 groups: PTR followed by chemotherapy (POC), upfront chemotherapy followed by PTR (UFC), and palliative chemotherapy (PC). The primary end points included median overall survival (OS) and progression-free survival (PFS). Clinical features were analysed using χ² test, while survival curves were generated using the Kaplan-Meier test. Propensity-score matching (PSM) was performed when comparing survival between POC and UFC groups.

Results:

From 2008 to 2014, 255 patients were identified and included into the POC (n = 101), UFC (n = 40), and PC (n = 114) groups. The UFC and POC groups had significantly better median OS compared with the PC group (40.7 vs 16.3 months, P < .0001; 39.7 vs 16.3 months, P < .0001). Before PSM, the UFC group had better median PFS than the POC and PC groups (18.5 vs 9.7 months, P = .038; 18.5 vs 6.1 months, P < .0001). After PSM, UFC has better PFS than POC (P = .038). And the UFC group did not have higher postoperative or preoperative morbidity compared with the POC group (P = .235).

Conclusions:

Primary tumour resection could improve the survival of patients with asmCRC. Compared with POC or PC, UFC was associated with a better median PFS without significantly increasing preoperative or postoperative morbidity.

Surgery improves the prognosis of colon mucinous adenocarcinoma with liver metastases: a SEER-based study

BACKGROUND

Mucinous adenocarcinoma (MC) is the second most common pathological type of colon carcinoma (CC). Colon cancer liver metastases (CLMs) are common and lethal, and complete resection of the primary tumour and metastases for CLM patients would be beneficial. However, there is still no consensus on the role of surgery for MC with liver metastases (M-CLM).

METHODS

Patients diagnosed with M-CLM or classical adenocarcinoma with CLM (A-CLM) from 2010 to 2013 in the Surveillance, Epidemiology, and End Results (SEER) database were retrieved. The clinicopathological features and overall survival (OS) and cancer-specific survival (CSS) data were compared and analysed.

RESULTS

The results showed that the M-CLM group had a larger tumour size, more right colon localizations, higher pT and pN stages, more female patients, and more retrieved and positive lymph nodes and accounted for a higher proportion of surgeries than the A-CLM group. The OS and CSS of M-CLM patients who underwent any type of surgery were significantly better than those of patients who did not undergo any surgery, but poorer than those of A-CLM patients who underwent surgery. Meanwhile, the OS and CSS of M-CLM and A-CLM patients who did not undergo any surgery were comparable. Compared with hemicolectomy, partial colectomy led to similar or better OS and CSS for M-CLM, and surgery was an independent protective factor for long-term survival in M-CLM.

CONCLUSIONS

M-CLM had distinct clinicopathological characteristics from A-CLM, and surgery could improve the survival and is an independent favourable prognostic factor for M-CLM. In addition, partial colectomy might be a non-inferiority choice as hemicolectomy for M-CLM according to the results from this study.

Survival outcome of palliative primary tumor resection for colorectal cancer patients with synchronous liver and/or lung metastases: A retrospective cohort study in the SEER database by propensity score matching analysis

BACKGROUND

There is a great matter of controversies whether some of these synchronous metastatic colorectal cancer patients can benefit from palliative primary tumor resection (pPTR) and there is still no reported randomized control trial to address this issue.

METHODS

Patients with microscopically proven metastatic colorectal cancer were identified within the SEER database (2010-2016). Patients were propensity matched 1:1 into pPTR and non-surgery groups and among the matched cohort, the univariable and multivariable Cox proportional hazards regression models were performed to identify predictors of survival. Median survival was calculated by using the Kaplan-Meier method.

RESULTS

Of 21,405 colorectal cancer patients diagnosed with synchronous liver and/or lung metastases, 7386 were identified in the matched cohort. The median overall survival was 12.0 months, 22.0 months in the non-surgery, surgery groups, respectively (p < 0.001) and the corresponding median cancer-specific survival was 13.0 months, 22.0 months, respectively (p < 0.001). Multivariable Cox regression analysis demonstrated that surgery was independently associated with improved overall survival (hazard ratio, 0.531) as well as cancer-specific survival (hazard ratio, 0.516). In stratified analyses by primary site and patterns of distant metastases, those patients with pPTR had better prognosis. In addition, stratified analysis revealed that trimodality therapy was linked with the greatest therapeutic effect followed by addition of chemotherapy to pPTR.

CONCLUSIONS

pPTR may offer some therapeutic benefits among carefully selected patients, and surgery-based multimodality therapy was associated with better survival.

The outcome of primary tumor resection in the unresectable stage IV colorectal cancer patients who received the bevacizumab-containing chemotherapy

Primary tumor resection (PTR) for unresectable metastatic colorectal cancer (mCRC) patients has been documented to be associated with postoperative hyper-neovascularization and enhanced growth of metastases, which may be prevented by bevacizumab. This study aimed to investigate the survival outcome of PTR in patients who received palliative bevacizumab-containing chemotherapy (BCT).From January 2006 to December 2018, medical records of 240 mCRC patients who received palliative BCT at a single tertiary colorectal cancer center were retrospectively reviewed. Patients were classified into three groups: PTR-a (PTR before BCT, n = 60), PTR-b (PTR during BCT, n = 17), and BCT-only group (n = 163). Resectable mCRCs or recurrent diseases were excluded, and the end-point was overall survival (OS) rate.Three groups had similar age, cell differentiation, location of the primary tumor, and the number of metastatic organs. More than two-thirds of patients who received PTR experienced disease-progressions (PD) during their postoperative chemotherapy-free time (PTR-a vs PTR-b; 66.7% vs 76.5%, P = .170), but OS was not inferior to the BCT-only group (PTR-a vs BCT-only; HR 0.477 [95% CI 0.302-0.754], P = .002/PTR-b vs BCT-only; HR 0.77 [95% CI 0.406-1.462], P = .425). The postoperative chemotherapy-free time was similar between PTR-a and PTR-b (median 32.0 [14-98] days vs 41.0 [18-71] days, P = .142), but non-obstructive indications (perforation, bleeding, pain) were the more frequent in the PTR-b than PTR-a. Young age, the number of BCT, and PTR-a were the independent factors for OS.The efficacy of the PTR for unresectable mCRC has been controversial, but this study demonstrated that PTR should be considered for the unresectable mCRC patients regardless before and during BCT.

Bevacizumab improves survival in metastatic colorectal cancer patients with primary tumor resection: A meta-analysis

It is not well determined whether primary tumor resection is associated with better outcomes in metastatic colorectal cancer (mCRC) patients treated with bevacizumab. In this meta-analysis, we aimed to assess the prognostic role of primary tumor resection in mCRC treated with bevacizumab. Electronic databases including the Cochrane library, Embase, and Pubmed were searched until April 2018. Clinical studies assessing the influence of primary tumor resection on the efficacy of bevacizumab in patients with mCRC were identified. The primary endpoint was overall survival (OS), and the secondary endpoint was progression-free survival (PFS). Seven studies including 2760 mCRC patients were finally included. The results of the meta-analysis were in favor of bevacizumab to patients with resected primary tumor in terms of OS (HR = 0.50, 95%CI: 0.39–0.64; p < 0.01), and PFS (HR = 0.65, 95%CI: 0.51–0.81; p < 0.01). Administration of bevacizumab in mCRC patients with resected primary tumor had a better OS (HR = 0.65, 95%CI: 0.56–0.74; p < 0.01), when compared to chemotherapy(CT). Adding bevacizumab to mCRC patients without resection of primary tumor also had a better OS (HR = 0.78, 95%CI: 0.65–0.94; p < 0.01) and PFS (HR = 0.71, 95%CI: 0.57–0.88; p < 0.01) compared to chemotherapy alone. In conclusion, mCRC patients with resected primary tumor have better survival than those without surgery of primary tumor when treated with bevacizumab. Primary tumor resection status should be taken into consideration when using bevacizumab in mCRC.

Is metastasectomy a worthy option?-the role of surgery in metastatic colon cancer to liver and lungs

Background

The role of surgery and metastasectomy is controversial in the treatment of stage IV colon cancer (CC). The aim of this study was to investigate the relationship between primary tumor resection (PTR) with metastasectomy and survival in patients diagnosed with metastatic CC.

Methods

The National Cancer Data Base (NCDB) was retrospectively queried for patients diagnosed with colon adenocarcinoma from 2004 to 2013. Patient demographics, clinical characteristics, and short-term outcomes were collected. Groups were generated based on if surgery was performed and, if so, was metastasectomy involved. Associations between groups were evaluated using Kruskal-Wallis and Pearson Chi-square tests. Overall survival (OS) was summarized using standard Kaplan-Meier methods. The association between surgical group and OS was evaluated using the log-rank test.

Results

Of 31,172 patients, 13,214 (42.4%) had surgery while 17,958 (57.6%) did not. Among these, 81.3% of patients had liver metastases only, while 18.7% of patients had both liver and lung metastases. Median OS was 15.1 months (95% CI: 14.8 to 15.5 months) for the entire cohort. However, median OS was significantly better for those who had surgery (either PTR alone or PTR with metastasectomy) compared to those who did not (21.8 vs. 7.5 months, P<0.001). Patients who received PTR with metastasectomy had worse median OS (20.5 vs. 21.8 months, P=0.035) compared to those who only received PTR (P=0.211).

Conclusions

PTR in select patients diagnosed with metastatic CC provides a remarkable improvement to survival rate. The role of metastasectomy remains controversial as no difference in survival outcomes exists between patients who received it and who did not.

ACORN: Observational Study of Bevacizumab in Combination With First-Line Chemotherapy for Treatment of Metastatic Colorectal Cancer in the UK

INTRODUCTION

Survival in metastatic colorectal cancer is worse than expected in the United Kingdom. Real-world data are needed to better understand UK-specific treatment practices that may explain this.

PATIENTS AND METHODS

The Avastin ColORectal Non-interventional (ACORN) study is a multicenter, prospective, UK-based, observational, phase 4 study (ClinicalTrials.gov, NCT01506167) that recruited patients with metastatic colorectal cancer scheduled to receive bevacizumab in combination with first-line chemotherapy as part of routine clinical practice. Primary end points included progression-free survival, overall survival (OS), serious adverse events (AEs), and grade 3 to 5 bevacizumab-related AEs.

RESULTS

A total of 714 patients were recruited between August 30, 2012, and February 4, 2014. Median follow-up was 16.4 months. Median first-line chemotherapy duration was 5.6 months, with capecitabine/oxaliplatin (265 [37.1%]) being the most common regimen. Median total chemotherapy duration was 8.1 months and did not vary by geographic location in the UK. Median progression-free survival (95% confidence interval) was 8.7 (8.2-9.1) months, and median OS was 17.8 (16.1-19.3) months. There was no significant difference in efficacy by chemotherapy regimen administered. Ninety-nine patients (13.9%) received bevacizumab after disease progression. The safety profile of bevacizumab was consistent with previous studies.

CONCLUSION

ACORN provided evidence that there were no clear differences observed in outcomes between bevacizumab with capecitabine-based chemotherapy and fluorouracil-based regimens, and confirmed the safety profile of bevacizumab in a real-world UK-based population. The lower-than-expected OS is likely due to the short total chemotherapy duration, less frequent use of bevacizumab after disease progression, and higher rates of in-situ primary tumors.

Survival outcomes following primary tumor resection for patients with incurable metastatic colorectal carcinoma: Experience from a single institution

OBJECTIVE

Palliative primary tumor resection (PTR) has been used for preventing and treating tumor-related complications. We aimed to determine whether PTR can increase overall survival (OS) in patients with unresectable metastatic colorectal cancer (CRC).

METHODS

A retrospective review of a prospectively collected database in a single center was performed. Patients diagnosed with metastatic CRC from January 2004 to December 2014 were included. Patients who had attained curative resection or had disease recurrence were excluded. All patients were discussed at a multidisciplinary tumor board where subsequent treatment decisions were made.

RESULTS

Altogether 408 patients were analyzed. Of these 145 received PTR with palliative chemotherapy (PC; group A), 110 received PC only (group B), 52 received PTR only (group C), while 101 received neither PTR nor PC (group D). Undergoing PTR led to statistically significant improvement in OS (22.7 months vs 12.1 months vs 6.9 months vs 2.7 months, P < 0.001). We performed subgroup analyses to control for potential confounders and found that the influence of PTR on OS persisted. With multivariate analysis, the predictors of poor OS were no PTR (hazards ratio [HR] 2.32, 95% confidence interval [CI] 1.82-2.96, P < 0.001), no PC (HR 4.25, 95% CI 3.27-5.33, P < 0.001) and the presence of peritoneal metastases (HR 1.37, 95% CI 1.06-1.78, P = 0.018). Diversion surgery did not lead to a statistical difference in OS.

CONCLUSIONS

The absences of PTR and PC, and peritoneal metastases are independently associated with decreased OS in patients with unresectable metastatic CRC. Randomized controlled trials are needed to verify this observation.

Modern-day palliative chemotherapy for metastatic colorectal cancer: does colonic resection affect survival?

BACKGROUND

Patients with metastatic colorectal cancer (mCRC) with surgically incurable metastases would be recommended for palliative chemotherapy (PC). The role of surgical intervention is debatable with no conclusive evidence for routine primary tumour resection (PTR) or stoma creation. We aimed to study if surgical intervention conferred a survival benefit in patients with mCRC who received upfront systemic therapy.

METHODS

A retrospective review of a prospectively collected database in a single centre was performed. Patients diagnosed with mCRC from January 2004 to December 2014 were included. We excluded patients who had an upfront surgical intervention, had no treatment with systemic therapy or had attained curative resection. The decision for surgery was based on the outcome of a multidisciplinary tumour board. Demographic, clinicopathological, treatment and follow-up data were collected. Univariate and multivariate analyses were performed.

RESULTS

Out of 408 patients with mCRC with incurable metastases, we analysed 124 patients who had upfront PC. Twenty-nine had PC + PTR (group A), 10 had PC + stoma (group B) and 85 had PC only (group C). Undergoing PTR led to significant improvement in overall survival (OS; 30.8 versus 13.4 versus 11.0 months, P < 0.001). With multivariate analysis, undergoing PTR and receiving biologics were independent good prognostic variables. Surgical resection was safe with minimal complications.

CONCLUSIONS

PTR was found to increase OS while stoma creation had no impact on OS. The benefits and safety of undergoing PTR may be a result of selection bias. Further prospective studies are required to confirm the observations of this study.

Meta-analysis of outcomes following resection of the primary tumour in patients presenting with metastatic colorectal cancer

BACKGROUND

It is not clear whether resection of the primary tumour (when there are metastases) alters survival and/or whether resection is associated with increased morbidity. This systematic review and meta-analysis assessed the prognostic value of primary tumour resection in patients presenting with metastatic colorectal cancer.

METHODS

A systematic review of MEDLINE/PubMed was performed on 12 March 2016, with no language or date restrictions, for studies comparing primary tumour resection versus conservative treatment without primary tumour resection for metastatic colorectal cancer. The quality of the studies was assessed using the MINORS and STROBE criteria. Differences in survival, morbidity and mortality between groups were estimated using random-effects meta-analysis.

RESULTS

Of 37 412 initially screened articles, 56 retrospective studies with 148 151 patients met the inclusion criteria. Primary tumour resection led to an improvement in overall survival of 7·76 (95 per cent c.i. 5·96 to 9·56) months (risk ratio (RR) for overall survival 0·50, 95 per cent c.i. 0·47 to 0·53), but did not significantly reduce the risk of obstruction (RR 0·50, 95 per cent c.i. 0·16 to 1·53) or bleeding (RR 1·19, 0·48 to 2·97). Neither was the morbidity risk altered (RR 1·14, 0·77 to 1·68). Heterogeneity between the studies was high, with a calculated I² of more than 50 per cent for most outcomes.

CONCLUSION

Primary tumour resection may provide a modest survival advantage in patients presenting with metastatic colorectal cancer.

Meta-analysis of oncologic effect of primary tumor resection in patients with unresectable stage IV colorectal cancer in the era of modern systemic chemotherapy

Purpose

The management of primary tumors in patients with stage IV colorectal cancer remains unclear. This meta-analysis evaluated the survival benefits of primary tumor resection (PTR) in patients with unresectable stage IV colorectal cancer in the era of modern chemotherapy.

Methods

Multiple comprehensive databases were searched for studies comparing survival outcomes in patients with metastatic colorectal cancer who did and did not undergo PTR. Outcome data were pooled, and overall effect size was calculated using random effect models.

Results

Seventeen nonrandomized studies involving 18,863 patients met the inclusion criteria. Meta-analysis showed that PTR significantly improved overall survival (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.56–0.71; P < 0.001) and progression free survival (HR, 0.76; 95% CI, 0.67–0.87; P < 0.001). Subgroup analyses and sensitivity analyses, performed by predefined methods, also indicated that PTR improved overall patient survival.

Conclusion

Palliative resection of the primary tumor may have survival benefits in patients with unresectable stage IV colorectal cancer. Randomized controlled trials are needed to determine the optimal treatment for these patients.

Asymptomatic primary tumour in incurable metastatic colorectal cancer: is there a role for surgical resection prior to systematic therapy or not?

INTRODUCTION

The role of the resection of asymptomatic primary colorectal cancer in patients with incurable disease is questionable.

AIM

To evaluate the impact of the resection of asymptomatic primary tumour on overall survival in patients with unresectable distant metastases.

MATERIAL AND METHODS

Patients treated in the National Cancer Institute, Lithuania, in the period 2008-2012, were selected retrospectively. The main inclusion criteria were: metastatic colorectal cancer (mCRC), endoscopically and histologically confirmed adenocarcinoma, without any symptoms for urgent operation, and at least one cycle of palliative chemotherapy administered. Information on patients' age, gender, tumour histology, localization of the tumour, regional lymph node involvement, number of metastatic sites, surgery and systemic treatment was collected prospectively. Eligible patients for the study were divided into two groups according to the initial treatment - surgery (patients who underwent primary tumour resection) and chemotherapy (patients who received chemotherapy without surgery). The impact of initial treatment strategy, tumour size and site, regional lymph nodes, grade of differentiation of adenocarcinoma and application of biotherapy on overall cumulative survival was estimated using the Kaplan-Meier method. To compare survival between groups the log-rank test was used. Cox regression analysis was employed to assess the effects of variables on patient survival.

RESULTS

The study group consisted of 183 patients: 103 men and 80 women. The median age was 66 years (range: 37-91). There were no notable imbalances with regard to age, gender, number of metastatic sites, metastases (such as pulmonary, peritoneal, liver, metastases into non-regional lymph nodes and other metastases), the number of received cycles of chemotherapy, first line chemotherapy type or biological therapy. Only 27 (14.8%) patients received biological therapy and the majority of them (n = 25, 92.6%) were treated with bevacizumab. For surgically treated patients 1-year survival was 71.2% (95% CI: 62.1-78.5) and 5-year survival was 4.0% (95% CI: 1.0-10.5). In the chemotherapy group, survival rates were lower - 43.9% (95% CI: 31.4-55.7) and 1.7% (95% CI: 0.1-8.1), respectively. Better survival rates were in the palliative surgery group. Multivariate analysis using the Cox proportional hazards model revealed that the initial palliative surgery and the application of biological therapy were statistically significant independent prognostic factors for survival.

CONCLUSIONS

Our findings suggest that palliative resectional surgery for the primary tumour in patients with incurable mCRC improves survival. Of course, one can argue that patients in the surgery group were "less problematic". Prospective randomized trials are needed to delineate precisely the role of palliative surgery of the primary tumour in these patients.

Bevacizumab Efficacy Is Influenced by Primary Tumor Resection in First-Line Treatment of Metastatic Colorectal Cancer in a Retrospective Multicenter Study

INTRODUCTION

There is no predictive factor of response to bevacizumab in metastatic colorectal cancer. Nevertheless, preclinical studies demonstrated an interaction between primary tumor and metastatic sites for the neoangiogenesis regulation. The primary objective of our study was to identify an effect of up-front primary tumor resection (UPTR) on bevacizumab efficacy.

PATIENTS AND METHODS

Between 2008 and 2010, we retrospectively analyzed progression-free survival (PFS) and overall survival (OS) of 316 patients with synchronous and metachronous metastatic colorectal cancer according to bevacizumab addition to first-line chemotherapy and UPTR.

RESULTS

Among 206 patients with UPTR, the addition of bevacizumab to chemotherapy significantly improved OS compared to chemotherapy alone (29.8 vs. 23.9 months respectively; hazard ratio [HR] 0.58; 95% confidence interval [CI], 0.40-0.83; P = .003). This effect was confirmed in multivariate analysis. There was also a nonsignificant trend toward improved PFS (9.7 vs. 8.4 months respectively; HR 0.71; 95% CI, 0.50-1.02; P = .062). Conversely, among 110 patients without UPTR, the addition of bevacizumab to chemotherapy had no effect on OS compared to chemotherapy alone (18.2 vs. 19.3 months respectively; HR 0.96; 95% CI, 0.65-1.42; P = .853). Bevacizumab significantly improved PFS (8.1 vs. 5.7 months respectively; HR 0.66; 95% CI, 0.45-0.96; P = .032) without confirmation in multivariate analysis.

CONCLUSION

In this retrospective study, bevacizumab seems to improve OS only in patients with UPTR, which could suggest a complementarity of both therapeutic modalities for antiangiogenic effect.

Moving towards best practice when using inverse probability of treatment weighting (IPTW) using the propensity score to estimate causal treatment effects in observational studies

The propensity score is defined as a subject's probability of treatment selection, conditional on observed baseline covariates. Weighting subjects by the inverse probability of treatment received creates a synthetic sample in which treatment assignment is independent of measured baseline covariates. Inverse probability of treatment weighting (IPTW) using the propensity score allows one to obtain unbiased estimates of average treatment effects. However, these estimates are only valid if there are no residual systematic differences in observed baseline characteristics between treated and control subjects in the sample weighted by the estimated inverse probability of treatment. We report on a systematic literature review, in which we found that the use of IPTW has increased rapidly in recent years, but that in the most recent year, a majority of studies did not formally examine whether weighting balanced measured covariates between treatment groups. We then proceed to describe a suite of quantitative and qualitative methods that allow one to assess whether measured baseline covariates are balanced between treatment groups in the weighted sample. The quantitative methods use the weighted standardized difference to compare means, prevalences, higher‐order moments, and interactions. The qualitative methods employ graphical methods to compare the distribution of continuous baseline covariates between treated and control subjects in the weighted sample. Finally, we illustrate the application of these methods in an empirical case study. We propose a formal set of balance diagnostics that contribute towards an evolving concept of ‘best practice’ when using IPTW to estimate causal treatment effects using observational data. © 2015 The Authors. Statistics in Medicine Published by John Wiley & Sons Ltd.

Neutrophil to lymphocyte ratio is a strong predictor of tumor recurrence in early colon cancers: A propensity score-matched analysis

BACKGROUND

Systemic inflammation and immune response play a crucial role in tumor growth, and the neutrophil to lymphocyte ratio (NLR) may be a simple way to assess the host inflammatory response. The NLR has been shown to be a prognostic indicator in many human tumors; in early colon cancers, it has been evaluated only in a few studies and its role remains controversial.

METHODS

We analyzed data from 503 colon cancer patients. The best cutoff value for NLR was defined by receiver operating characteristic curve analysis. We grouped 276 Dukes A/B colon cancers, not receiving adjuvant chemotherapy, into low (<2.36) and high (>2.36) NLR and subjected to further analyses related to disease-free survival (DFS). A propensity score-matched analysis and the inverse probability of treatment weighting (IPTW) were performed to avoid confounding bias.

RESULTS

The NLR correlated with tumor stage and oncologic outcome. The best NLR cutoff value was identical in the whole cohort and in Dukes A/B patients. Low NLR patients had a significantly better DFS rate than high NLR patients (hazard ratio [HR], 0.27; P = .0001); along with elevated carcinoembryonic antigen levels and Dukes B stage, high NLR was an independent prognostic factor of worse prognosis (HR, 2.86; P = .0033). Even in Dukes A patients, NLR discriminated between relapsing and nonrelapsing patients. Propensity score and IPTW analyses confirmed such results, thus excluding possible misinterpretation.

CONCLUSION

Preoperative NLR, an inexpensive and readily available biomarker, can predict tumor relapse and should be assessed for implementation of tailored therapy in early stage colon cancer.