Can you see the wood for the trees? Making sense of forest plots in systematic reviews 2. Analysis of the combined results from the included studies

Personalized Surgery for Gastric Adenocarcinoma: A Meta-analysis of D1 versus D2 Lymphadenectomy

BACKGROUND

The recent publication of 5-year survival data for the Italian Gastric Cancer Study Group (IGCSG) D1 versus D2 lymphadenectomy for gastric cancer trial adds important data for analysis of whether a D2 lymphadenectomy improves survival.

METHODS

Systematic searches were conducted using Medline, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1985 to February 1, 2014. Meta-analyses were performed using RevMan version 5 software. Long-term outcomes were analyzed. Subgroup analyses of T and N stage were performed.

RESULTS

Outcomes of four randomized, controlled trials involving 1,599 patients (823 D1: 776 D2) enrolled from 1982 to 2005 were included for qualitative analysis and quantitative meta-analysis. Despite the addition of long-term survival data from the IGCSG, 5-year overall and nodal status survival was similar between D1 and D2 trials. However, subgroup analysis revealed a survival benefit for T3 patients (odds ratio 1.64, 95 % confidence interval 1.01-2.67) and a trend for survival benefit for advanced nodal stage (odds ratio 1.36, 95 % confidence interval 0.98-1.87) with D2 compared with D1 lymphadenectomy.

CONCLUSIONS

As recent studies have demonstrated comparable short-term surgical outcomes for both D1 and D2 lymphadenectomies, consideration should be made for more extensive lymph node dissection among patients with advanced stage.

High-resolution melting curve analysis for rapid detection of rifampin resistance in Mycobacterium tuberculosis: a meta-analysis

A rapid, simple, accurate, and affordable method for the detection of drug-resistant tuberculosis is very critical for the selection of antimicrobial therapy and management of patient treatment. High-resolution melting curve analysis has been used for the detection of rifampin resistance in Mycobacterium tuberculosis and has shown promise. We did a systematic review and meta-analysis of published studies to evaluate the accuracy of high-resolution melting curve analysis for the detection of rifampin resistance in clinical M. tuberculosis isolates. We searched the PubMed, BIOSIS Previews, and Web of Science databases to identify studies and included them according to predetermined criteria. We used the DerSimonian-Laird random-effects model to calculate pooled measures and applied Moses' constant for linear models to fit the summary receiver operating characteristic curve. According to the selection criteria, most of the identified studies were excluded, and only seven studies were included in the final analysis. The overall sensitivity of the high-resolution melting curve analysis was 94% (95% confidence interval [CI], 92% to 96%), and the overall specificity was very high at 99% (95% CI, 98% to 100%). The values for the pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 63.39 (95% CI, 30.21 to 133.00), 0.06 (95% CI, 0.04 to 0.09), and 892.70 (95% CI, 385.50 to 2,067.24), respectively. There was no significant heterogeneity across all included studies for the measurements we evaluated. The summary receiver operating characteristic curve for the same data shows an area of 0.99 and a Q* value of 0.97. High-resolution melting curve analysis has high sensitivity and specificity for the detection of rifampin resistance in clinical M. tuberculosis isolates. This method might be a good alternative to conventional drug susceptibility tests in clinical practice.

A meta-analysis of D1 versus D2 lymph node dissection

BACKGROUND

Surgery is the only curative treatment for patients with gastric cancer. However, the extent of lymph node dissection is still debated. Therefore, with the publication of newer trial results, we conducted an updated meta-analysis of D1 versus D2 randomized controlled trials comparing outcomes.

METHODS

Systematic searches were conducted using Medline, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 1985, to December 31, 2010. Meta-analyses were performed using RevMan v5 software. Both short- and long-term outcomes were analyzed. Subgroup analyses of T stage and spleen/pancreas resection versus preservation were performed.

RESULTS

Outcomes of 5 randomized trials involving 1642 patients (845 D1, 797 D2) enrolled from 1982 to 2005 were included. Despite the addition of the more recent trials, overall hospital mortality and reoperation rates were still higher in D2 cases. Subgroup analysis of recent trials and spleen/pancreas preservation revealed no significant difference in hospital mortality between groups. Five-year overall survival was similar between D1 versus D2 trials. Sub-analysis by tumor depth and spleen/pancreas preservation detected trends for improved survival with D2 lymphadenectomy in T3/T4 patients and those with spleen/pancreas preservation.

CONCLUSION

Earlier trials show that D2 dissections have higher operative mortality, while recent trials have similar rates. A trend of improved survival exists among D2 patients who did not undergo resection of the spleen or pancreas, as well as for patients with T3/T4 cancers.

What is the accuracy of sentinel lymph node biopsy for gastric cancer? A systematic review

BACKGROUND

In gastric cancer, the utility of sentinel lymph node (SLN) biopsy has not been established. SLN may be a good predictor of the pathological status of other lymph nodes and thus the necessity for more extensive surgery or lymph node dissection. We aimed to identify and synthesize findings on the performance of SLN biopsies in gastric cancer.

METHODS

Electronic literature searches were conducted using Medline, EMBASE, and the Cochrane Central Register of Controlled Trials from 1998 to 2009. Titles and abstracts were independently rated for relevance by a minimum of two reviewers. Techniques, detection rates, accuracy, sensitivity, specificity, and false-negative rates (FNRs) were analyzed. Analysis was performed based on the FNR.

RESULTS

Twenty-six articles met our inclusion criteria. SLN detection using the dye method (DM) was reviewed in 18 studies, the radiocolloid method (RM) was used in 12 studies, and both dye and radiocolloid methods (DUAL) were used in 5 studies. The DM had an overall calculated FNR of 34.7% (95% confidence interval [CI] 21.2, 48.1). The RM had an overall calculated FNR of 18.5% (95% CI 9.1, 28.0). DUAL had an overall calculated FNR of 13.1% (95% CI -0.9, 27.2).

CONCLUSION

Application of the SLN technique may be practical for early gastric cancer. The use of DUAL for identifying SLN may yield a lower FNR than either method alone, although statistical significance was not met.

Effect of verification bias on the sensitivity of fecal occult blood testing: a meta-analysis

OBJECTIVES

There is controversy regarding the sensitivity of fecal occult blood tests (FOBT) for detecting colorectal cancer. Many of the published studies failed to correct for verification bias which may have increased the sensitivity.

METHODS

A meta-analysis of published studies evaluating the sensitivity and specificity of chemical-based FOBT for colorectal cancer was performed. Studies were included if both cancer and control subjects underwent confirmatory testing. We also included studies that attempted to correct for verification bias by either performing colonoscopy on all subjects regardless of the FOBT result or by using longitudinal follow-up. We then compared the sensitivity, specificity, and other diagnostic characteristics of the studies that attempted to correct for verification (n=10) vs. those that did not correct for this bias (n=19).

RESULTS

The pooled sensitivity of guaiac-based FOBT for colorectal cancer of studies without verification bias was significantly lower than those studies with this bias [0.36 (95% CI 0.25-0.47) vs. 0.70 (95% CI 0.60-0.80), p=0.001]. The pooled specificity of the studies without verification bias was higher [0.96 (95% CI 0.94-0.97) vs. 0.88 (95% CI 0.84-0.91), p<0.005]. There was no significant difference in the area under the summary receiver operating characteristic curves. More sensitive chemical-based FOBT methods (e.g., Hemoccult® SENSA®) had a higher sensitivity but a lower specificity than standard guaiac methods.

CONCLUSIONS

The sensitivity of guaiac-based FOBT for colorectal cancer has been overestimated as a result of verification bias. This test may not be sensitive enough to serve as an effective screening option for colorectal cancer.