A framework for identifying treatment-covariate interactions in individual participant data network meta-analysis

Background: Stratified medicine seeks to identify patients most likely to respond to treatment. Individual participant data (IPD) network meta‐analysis (NMA) models have greater power than individual trials to identify treatment‐covariate interactions (TCIs). Treatment‐covariate interactions contain “within” and “across” trial interactions, where the across‐trial interaction is more susceptible to confounding and ecological bias.

Methods: We considered a network of IPD from 37 trials (5922 patients) for cervical cancer (2394 events), where previous research identified disease stage as a potential interaction covariate. We compare 2 models for NMA with TCIs: (1) 2 effects separating within‐ and across‐trial interactions and (2) a single effect combining within‐ and across‐trial interactions. We argue for a visual assessment of consistency of within‐ and across‐trial interactions and consider more detailed aspects of interaction modelling, eg, common vs trial‐specific effects of the covariate. This leads us to propose a practical framework for IPD NMA with TCIs.

Results: Following our framework, we found no evidence in the cervical cancer network for a treatment‐stage interaction on the basis of the within‐trial interaction. The NMA provided additional power for an across‐trial interaction over and above the pairwise evidence. Following our proposed framework, we found that the within‐ and across‐trial interactions should not be combined.

Conclusion: Across‐trial interactions are susceptible to confounding and ecological bias. It is important to separate the sources of evidence to check their consistency and identify which sources of evidence are driving the conclusion. Our framework provides practical guidance for researchers, reducing the risk of unduly optimistic interpretation of TCIs.

What is the optimal systemic treatment of men with metastatic, hormone-naive prostate cancer? A STOPCAP systematic review and network meta-analysis

Background

Our prior Systemic Treatment Options for Cancer of the Prostate systematic reviews showed improved survival for men with metastatic hormone-naive prostate cancer when abiraterone acetate plus prednisolone/prednisone (AAP) or docetaxel (Doc), but not zoledronic acid (ZA), were added to androgen-deprivation therapy (ADT). Trial evidence also suggests a benefit of combining celecoxib (Cel) with ZA and ADT. To establish the optimal treatments, a network meta-analysis (NMA) was carried out based on aggregate data (AD) from all available studies.

Methods

Overall survival (OS) and failure-free survival data from completed Systemic Treatment Options for Cancer of the Prostate reviews of Doc, ZA and AAP and from recent trials of ZA and Cel contributed to this comprehensive AD-NMA. The primary outcome was OS. Correlations between treatment comparisons within one multi-arm, multi-stage trial were estimated from control-arm event counts. Network consistency and a common heterogeneity variance were assumed.

Results

We identified 10 completed trials which had closed to recruitment, and one trial in which recruitment was ongoing, as eligible for inclusion. Results are based on six trials including 6204 men (97% of men randomised in all completed trials). Network estimates of effects on OS were consistent with reported comparisons with ADT alone for AAP [hazard ration (HR) = 0.61, 95% confidence interval (CI) 0.53-0.71], Doc (HR = 0.77, 95% CI 0.68-0.87), ZA + Cel (HR = 0.78, 95% CI 0.62-0.97), ZA + Doc (HR = 0.79, 95% CI 0.66-0.94), Cel (HR = 0.94 95% CI 0.75-1.17) and ZA (HR = 0.90 95% CI 0.79-1.03). The effect of ZA + Cel is consistent with the additive effects of the individual treatments. Results suggest that AAP has the highest probability of being the most effective treatment both for OS (94% probability) and failure-free survival (100% probability). Doc was the second-best treatment of OS (35% probability).

Conclusions

Uniquely, we have included all available results and appropriately accounted for inclusion of multi-arm, multi-stage trials in this AD-NMA. Our results support the use of AAP or Doc with ADT in men with metastatic hormone-naive prostate cancer. AAP appears to be the most effective treatment, but it is not clear to what extent and whether this is due to a true increased benefit with AAP or the variable features of the individual trials. To fully account for patient variability across trials, changes in prognosis or treatment effects over time and the potential impact of treatment on progression, a network meta-analysis based on individual participant data is in development.

Strategies to improve retention in randomised trials: a Cochrane systematic review and meta-analysis

OBJECTIVE

To quantify the effect of strategies to improve retention in randomised trials.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Sources searched: MEDLINE, EMBASE, PsycINFO, DARE, CENTRAL, CINAHL, C2-SPECTR, ERIC, PreMEDLINE, Cochrane Methodology Register, Current Controlled Trials metaRegister, WHO trials platform, Society for Clinical Trials (SCT) conference proceedings and a survey of all UK clinical trial research units.

REVIEW METHODS

Included trials were randomised evaluations of strategies to improve retention embedded within host randomised trials. The primary outcome was retention of trial participants. Data from trials were pooled using the fixed-effect model. Subgroup analyses were used to explore the heterogeneity and to determine whether there were any differences in effect by the type of strategy.

RESULTS

38 retention trials were identified. Six broad types of strategies were evaluated. Strategies that increased postal questionnaire responses were: adding, that is, giving a monetary incentive (RR 1.18; 95% CI 1.09 to 1.28) and higher valued incentives (RR 1.12; 95% CI 1.04 to 1.22). Offering a monetary incentive, that is, an incentive given on receipt of a completed questionnaire, also increased electronic questionnaire response (RR 1.25; 95% CI 1.14 to 1.38). The evidence for shorter questionnaires (RR 1.04; 95% CI 1.00 to 1.08) and questionnaires relevant to the disease/condition (RR 1.07; 95% CI 1.01 to 1.14) is less clear. On the basis of the results of single trials, the following strategies appeared effective at increasing questionnaire response: recorded delivery of questionnaires (RR 2.08; 95% CI 1.11 to 3.87); a 'package' of postal communication strategies (RR 1.43; 95% CI 1.22 to 1.67) and an open trial design (RR 1.37; 95% CI 1.16 to 1.63). There is no good evidence that the following strategies impact on trial response/retention: adding a non-monetary incentive (RR=1.00; 95% CI 0.98 to 1.02); offering a non-monetary incentive (RR=0.99; 95% CI 0.95 to 1.03); 'enhanced' letters (RR=1.01; 95% CI 0.97 to 1.05); monetary incentives compared with offering prize draw entry (RR=1.04; 95% CI 0.91 to 1.19); priority postal delivery (RR=1.02; 95% CI 0.95 to 1.09); behavioural motivational strategies (RR=1.08; 95% CI 0.93 to 1.24); additional reminders to participants (RR=1.03; 95% CI 0.99 to 1.06) and questionnaire question order (RR=1.00, 0.97 to 1.02). Also based on single trials, these strategies do not appear effective: a telephone survey compared with a monetary incentive plus questionnaire (RR=1.08; 95% CI 0.94 to 1.24); offering a charity donation (RR=1.02, 95% CI 0.78 to 1.32); sending sites reminders (RR=0.96; 95% CI 0.83 to 1.11); sending questionnaires early (RR=1.10; 95% CI 0.96 to 1.26); longer and clearer questionnaires (RR=1.01, 0.95 to 1.07) and participant case management by trial assistants (RR=1.00; 95% CI 0.97 to 1.04).

CONCLUSIONS

Most of the trials evaluated questionnaire response rather than ways to improve participants return to site for follow-up. Monetary incentives and offers of monetary incentives increase postal and electronic questionnaire response. Some strategies need further evaluation. Application of these results would depend on trial context and follow-up procedures.

Use of strategies to improve retention in primary care randomised trials: a qualitative study with in-depth interviews

OBJECTIVE

To explore the strategies used to improve retention in primary care randomised trials.

DESIGN

Qualitative in-depth interviews and thematic analysis.

PARTICIPANTS

29 UK primary care chief and principal investigators, trial managers and research nurses.

METHODS

In-depth face-to-face interviews.

RESULTS

Primary care researchers use incentive and communication strategies to improve retention in trials, but were unsure of their effect. Small monetary incentives were used to increase response to postal questionnaires. Non-monetary incentives were used although there was scepticism about the impact of these on retention. Nurses routinely used telephone communication to encourage participants to return for trial follow-up. Trial managers used first class post, shorter questionnaires and improved questionnaire designs with the aim of improving questionnaire response. Interviewees thought an open trial design could lead to biased results and were negative about using behavioural strategies to improve retention. There was consensus among the interviewees that effective communication and rapport with participants, participant altruism, respect for participant's time, flexibility of trial personnel and appointment schedules and trial information improve retention. Interviewees noted particular challenges with retention in mental health trials and those involving teenagers.

CONCLUSIONS

The findings of this qualitative study have allowed us to reflect on research practice around retention and highlight a gap between such practice and current evidence. Interviewees describe acting from experience without evidence from the literature, which supports the use of small monetary incentives to improve the questionnaire response. No such evidence exists for non-monetary incentives or first class post, use of which may need reconsideration. An exploration of barriers and facilitators to retention in other research contexts may be justified.

Aspirin and cancer: has aspirin been overlooked as an adjuvant therapy?

Aspirin inhibits the enzyme cyclooxygenase (Cox), and there is a significant body of epidemiological evidence demonstrating that regular aspirin use is associated with a decreased incidence of developing cancer. Interest focussed on selective Cox-2 inhibitors both as cancer prevention agents and as therapeutic agents in patients with proven malignancy until concerns were raised about their toxicity profile. Aspirin has several additional mechanisms of action that may contribute to its anti-cancer effect. It also influences cellular processes such as apoptosis and angiogenesis that are crucial for the development and growth of malignancies. Evidence suggests that these effects can occur through Cox-independent pathways questioning the rationale of focussing on Cox-2 inhibition alone as an anti-cancer strategy. Randomised studies with aspirin primarily designed to prevent cardiovascular disease have demonstrated a reduction in cancer deaths with long-term follow-up. Concerns about toxicity, particularly serious haemorrhage, have limited the use of aspirin as a cancer prevention agent, but recent epidemiological evidence demonstrating regular aspirin use after a diagnosis of cancer improves outcomes suggests that it may have a role in the adjuvant setting where the risk:benefit ratio will be different.

A critical review of methods for the assessment of patient-level interactions in individual participant data meta-analysis of randomized trials, and guidance for practitioners

OBJECTIVE

Treatments may be more effective in some patients than others, and individual participant data (IPD) meta-analysis of randomized trials provides perhaps the best method of investigating treatment-covariate interactions. Various methods are used; we provide a comprehensive critique and develop guidance on method selection.

STUDY DESIGN AND SETTING

We searched MEDLINE to identify all frequentist methods and appraised them for simplicity, risk of bias, and power. IPD data sets were reanalyzed.

RESULTS

Four methodological categories were identified: PWT: pooling of within-trial covariate interactions; OSM: "one-stage" model with a treatment-covariate interaction term; TDCS: testing for difference between covariate subgroups in their pooled treatment effects; and CWA: combining PWT with meta-regression. Distinguishing across- and within-trial information is important, as the former may be subject to ecological bias. A strategy is proposed for method selection in different circumstances; PWT or CWA are natural first steps. The OSM method allows for more complex analyses; TDCS should be avoided. Our reanalysis shows that different methods can lead to substantively different findings.

CONCLUSION

The choice of method for investigating interactions in IPD meta-analysis is driven mainly by whether across-trial information is considered for inclusion, a decision, which depends on balancing possible improvement in power with an increased risk of bias.

One-stage parametric meta-analysis of time-to-event outcomes

Methodology for the meta-analysis of individual patient data with survival end-points is proposed. Motivated by questions about the reliance on hazard ratios as summary measures of treatment effects, a parametric approach is considered and percentile ratios are introduced as an alternative to hazard ratios. The generalized log-gamma model, which includes many common time-to-event distributions as special cases, is discussed in detail. Likelihood inference for percentile ratios is outlined. The proposed methodology is used for a meta-analysis of glioma data that was one of the studies which motivated this work. A simulation study exploring the validity of the proposed methodology is available electronically. Copyright © 2010 John Wiley & Sons, Ltd.

Substantial improvement in UK cervical cancer survival with chemoradiotherapy: results of a Royal College of Radiologists' audit

AIMS

To compare survival and late complications between patients treated with chemoradiotherapy and radiotherapy for locally advanced cervix cancer.

MATERIALS AND METHODS

A Royal College of Radiologists' audit of patients treated with radiotherapy in UK cancer centres in 2001-2002. Survival, recurrence and late complications were assessed for patients grouped according to radical treatment received (radiotherapy, chemoradiotherapy, postoperative radiotherapy or chemoradiotherapy) and non-radical treatment. Late complication rates were assessed using the Franco-Italian glossary.

RESULTS

Data were analysed for 1243 patients from 42 UK centres. Overall 5-year survival was 56% (any radical treatment); 44% (radical radiotherapy); 55% (chemoradiotherapy) and 71% (surgery with postoperative radiotherapy). Overall survival at 5 years was 59% (stage IB), 44% (stage IIB) and 24% (stage IIIB) for women treated with radiotherapy, and 65% (stage IB), 61% (stage IIB) and 44% (stage IIIB) for those receiving chemoradiotherapy. Cox regression showed that survival was significantly better for patients receiving chemoradiotherapy (hazard ratio=0.77, 95% confidence interval 0.60-0.98; P=0.037) compared with those receiving radiotherapy taking age, stage, pelvic node involvement and treatment delay into account. The grade 3/4 late complication rate was 8% (radiotherapy) and 10% (chemoradiotherapy). Although complications continued to develop up to 7 years after treatment for those receiving chemoradiotherapy, there was no apparent increase in overall late complications compared with radiotherapy alone when other factors were taken into account (hazard ratio=0.94, 95% confidence interval 0.71-1.245; P=0.667).

DISCUSSION

The addition of chemotherapy to radiotherapy seems to have improved survival compared with radiotherapy alone for women treated in 2001-2002, without an apparent rise in late treatment complications.

Adjuvant chemotherapy, with or without postoperative radiotherapy, in operable non-small-cell lung cancer: two meta-analyses of individual patient data

BACKGROUND

Many randomised controlled trials have investigated the effect of adjuvant chemotherapy in operable non-small-cell lung cancer. We undertook two comprehensive systematic reviews and meta-analyses to establish the effects of adding adjuvant chemotherapy to surgery, or to surgery plus radiotherapy.

METHODS

We included randomised trials, not confounded by additional therapeutic differences between the two groups and that started randomisation on or after Jan 1, 1965, which compared surgery plus adjuvant chemotherapy versus surgery alone, or surgery plus adjuvant radiotherapy and chemotherapy versus surgery plus adjuvant radiotherapy. Updated individual patient data were collected, checked, and included in meta-analyses stratified by trial. The primary endpoint was overall survival, defined as time from randomisation until death by any cause. All analyses were by intention to treat.

FINDINGS

The first meta-analysis of surgery plus chemotherapy versus surgery alone was based on 34 trial comparisons and 8447 patients (3323 deaths). We recorded a benefit of adding chemotherapy after surgery (hazard ratio [HR] 0.86, 95% CI 0.81-0.92, p<0.0001), with an absolute increase in survival of 4% (95% CI 3-6) at 5 years (from 60% to 64%). The second meta-analysis of surgery plus radiotherapy and chemotherapy versus surgery plus radiotherapy was based on 13 trial comparisons and 2660 patients (1909 deaths). We recorded a benefit of adding chemotherapy to surgery plus radiotherapy (HR 0.88, 95% CI 0.81-0.97, p=0.009), representing an absolute improvement in survival of 4% (95% CI 1-8) at 5 years (from 29% to 33%). In both meta-analyses we noted little variation in effect according to the type of chemotherapy, other trial characteristics, or patient subgroup.

INTERPRETATION

The addition of adjuvant chemotherapy after surgery for patients with operable non-small-cell lung cancer improves survival, irrespective of whether chemotherapy was adjuvant to surgery alone or adjuvant to surgery plus radiotherapy.

FUNDING

UK Medical Research Council, Institut Gustave-Roussy, Programme Hospitalier de Recherche Clinique (AOM 05 209), Ligue Nationale Contre le Cancer, and Sanofi-Aventis.

Impact of K-ras status on the effects of EGFR-targeted monoclonal antibody (MAb) therapy in advanced colorectal cancer (ACRC): A systematic review and meta-analysis of randomized controlled trials (RCTs)

4122

Background: A recent systematic review, based largely on non-randomised, retrospective studies, suggested that K-ras mutations may identify patients who do not benefit from cetuximab and panitumumab. In support of this hypothesis, four RCTs have shown a lack of benefit or detriment of EGFR-targeted therapy in patients with K-ras mutations. In this systematic review, we aim to provide a comprehensive and unbiased synthesis of the effects of these MAbs, by K-ras status, in both chemotherapy (CT) responsive and CT-refractory ACRC patients. Methods: A systematic review and meta-analysis of all relevant RCTs is ongoing. Progression-free survival (PFS) is the primary outcome, with survival and response as secondary outcomes. We have conducted systematic searches of a number of trial sources. Data on trial and patient characteristics, and outcome have been extracted from trial reports or presentations, for all patients and for K-ras wild-type and mutant cohorts. Where possible, trial results were pooled in a stratified-by- trial meta-analysis. For unpublished RCTs, or those published with insufficient information, we are seeking further data. Results: Searches identified 15 eligible RCTs in CT-responsive patients, 12 using cetuximab and 3 panitumumab. Three of these trials included bevacizumab in both arms. PFS has only been reported for 6 RCTs, so further data are needed to ensure an unbiased analysis. Only two RCTs were identified in CT-refractory patients. Together, these showed an improvement in PFS with anti-EGFR MAb (HR=0.61, 95% CI 0.49–0.76, p<0.0001). Furthermore, there was a significant difference in the size of the effect by K-ras status (interaction p<0.0001), with an improvement in PFS for patients with wild type K-ras, (HR=0.43, 95% CI 0.35–0.52, p<0.0001), but not those with mutant K-ras (HR=0.99 95% CI 0.80–1.23, p=0.93). Conclusions: These preliminary results suggest that the benefits of anti-EGFR MAb therapy, at least in CT-refractory patients, are confined to those with wild type K-ras. Results for CT-responsive patients, and updated analyses for CT-refractory patients, will be presented.

[Table: see text]

Supportive care and chemotherapy (CT) versus supportive care alone in advanced non-small cell lung cancer (NSCLC): A meta-analysis using individual patient data (IPD) from randomised clinical trials (RCTs)

7582

Background: Building on a previous IPD meta-analysis of CT (BMJ 1995;311:899–909) which suggested that CT may have a role in the treatment of NSCLC, we have carried out a new, up-to-date IPD meta-analysis. This includes RCTs, regimens and outcomes that were not available in 1995. This new meta-analysis examines the role of CT in 7 treatment comparisons. Here we report the effectiveness of supportive care plus CT compared with supportive care alone. Methods: We conducted a systematic search for RCTs followed by the central collection, checking and re-analysis of updated IPD. Results from individual RCTs were combined using the stratified (by trial) log rank test to calculate individual and pooled hazard ratios (HRs). Previously included RCTs using long-term alkylating agents were excluded from this analysis due to their antiquity. Results: IPD were obtained on 2,666 patients from 15 RCTs. 11 RCTs used cisplatin-based CT regimens, 4 RCTs used single agent CT (etoposide, navelbine, gemcitabine, paclitaxel). This added 6 RCTs and 1,702 patients to the 1995 analyses. The results show a highly significant benefit of CT on survival (HR=0.78 95% Confidence Interval 0.71–0.84, p<0.000001), with an absolute benefit of 8% (from 20% to 28%) at 12 months across all patients. There was no evidence of a difference in effect (p=0.69) between trials that used cisplatin-based regimens (11 RCTs, HR=0.76), etoposide alone (1 RCT, HR=0.87) or newer single agents (3 RCTs, HR=0.79) (Interaction p=0.69). There was no evidence that any patient subgroup defined by age, sex, stage or histology benefited more or less from CT. The absolute benefit of CT at 12 months did vary according to WHO/ECOG (or equivalent) performance status. PS 0=8% (from 26% to 34%), PS 1=8% (from 18% to 26%), PS 2=5% (from 6% to 11%) and PS 3=4% (from 5% to 9%). Conclusion: The results demonstrate a substantial and consistent relative benefit of CT in advanced NSCLC. The effectiveness of newer agents such as navelbine, paclitaxel and gemcitabine (used as single agents) appears to be similar to that of cisplatin combined with older agents such as vindesine and mitomycin C. The absolute effect of CT varied according to performance status.

No significant financial relationships to disclose.

Surgery and adjuvant chemotherapy (CT) compared to surgery alone in non-small cell lung cancer (NSCLC): A meta-analysis using individual patient data (IPD) from randomized clinical trials (RCT)

7552

Background: A previous IPD meta-analysis (BMJ 1995;311:899) that suggested CT may have a role in the treatment of NSCLC has been updated. This includes RCTs, regimens and outcomes that were not available in 1995. The meta-analysis examines the role of CT in 7 treatment comparisons. Here we report on the effectiveness of surgery plus adjuvant CT compared with surgery alone. Methods: We conducted a systematic search for RCTs followed by the central collection, checking and re-analysis of updated IPD. Results from RCTs were combined using the stratified (by trial) log rank test to calculate individual and pooled hazard ratios (HRs). Previously included RCTs using long-term alkylating agents were excluded from this analysis due to their antiquity. Results: IPD were obtained on 8147 patients from 30 RCTs. 15 RCTs used a cisplatin combination without Tegafur/Tegafur+Uracil (UFT), 8 RCTs used Tegafur/UFT without cisplatin and 7 RCTs used Tegafur/UFT and cisplatin. This represents 95% of all known randomised patients and adds 18 trials and 5835 patients to the 1995 analyses. The results show a highly significant benefit of CT on survival (HR=0.86 95% CI 0.81–0.93, p<0.000001), with an absolute benefit of 4% (from 60% to 64%) at 5 years. Results were similar for recurrence-free survival and time to distant recurrence, but there was a larger effect on time to local recurrence ( Table ). There was no clear difference in effect by type of CT given. There was no clear evidence that any patient subgroup defined by age, sex or histology benefited more or less from CT. There was a suggestion of a trend in effect by stage (p=0.047), this will be explored further. Conclusion: The results demonstrate conclusively and consistently a benefit of adjuvant CT in resected NSCLC, irrespective of the regimen used, the patient subgroup treated or the endpoint assessed, thus providing reliable estimates on which to base future policy and research.

[Table: see text] [Table: see text]

Chemotherapy for advanced, recurrent or metastatic endometrial cancer: a systematic review of Cochrane collaboration

BACKGROUND

Cytotoxic chemotherapy has a limited place in the management of advanced or recurrent endometrial cancer. Commonly used agents include cisplatin and doxorubicin, but the side-effect profile may be unacceptable for many patients. The feasibility of administration of combination chemotherapy is limited in many patients on account of significant co-morbidity. While early-stage endometrial adenocarcinoma is a common gynaecological cancer with a favourable prognosis, advanced or recurrent disease presents a difficult management problem. The platinum and anthracycline compounds have been widely used for many years, but their impact on progression-free survival (PFS) and overall survival (OS) is not clear. This systematic review aimed to evaluate both the benefits and adverse effects of cytotoxic chemotherapy in these women.

PATIENTS AND METHODS

We carried out systematic searches for randomised controlled trials (RCTs) comparing chemotherapy with another intervention. Data were extracted from trial reports or supplied by investigators. Where possible, hazard ratios (HRs) were calculated for OS and PFS and odds ratios (ORs) were calculated for acute toxicity. The impact of more versus less intensive chemotherapy on OS, PFS and acute toxicity was assessed in a meta-analysis.

RESULTS

Eleven eligible RCTs were identified that recruited 2288 patients. A meta-analysis of six of these trials found that PFS [HR = 0.80, 95% confidence interval (CI) 0.71-0.90; P = 0.004], but not OS (HR = 0.90, 95% CI 0.80-1.03; P = 0.12), was significantly improved when more intensive chemotherapy was compared with less intensive chemotherapy. OS was improved when doxorubicin, cisplatin and other drugs were compared with doxorubicin and cisplatin. Toxicity was generally higher with more chemotherapy. There was insufficient evidence to assess the effect of chemotherapy on symptom control or quality of life (QoL). Platinums, anthracyclines and taxanes were the most studied in phase II trials and combinations gave the best responses, but patient selection and pre-treatment was very variable.

CONCLUSIONS

More intense combination chemotherapy significantly improves the disease-free survival and the data indicate a modest improvement in OS. The addition of anthracyclines (e.g. doxorubicin) or the taxanes [e.g. paclitaxel (Taxol)] to cisplatin increases the response rate. More intensive regimens are associated with the gain in survival. However, grade 3 and 4 myelosuppression and gastrointestinal toxicity are also increased. Future developments are likely to exploit specific molecular characteristics of endometrial cancers, including their hormone dependence, growth factor target overexpression and PTEN loss. While no one drug or regimen offers a clear benefit for women with advanced endometrial cancer, platinum drugs, anthracyclines and paclitaxel seem the most promising agents. Future trials should address the impact of such agents on QoL and symptom control in addition to survival. Chemotherapy and endocrine therapy need to be compared directly in an RCT.

Concomitant hydroxyurea plus radiotherapy versus radiotherapy for carcinoma of the uterine cervix: a systematic review

We identified eight randomised control trials of hydroxyurea and radiation versus radiotherapy alone (six published in full and two abstracts). Most concluded that outcomes were improved by use of hydroxyurea. However, methodological problems associated with these trials included small sample size, a large number of patient exclusions post randomisation, differing outcome definitions, subgroup analyses of already small numbers of patients and questionable rules for censoring, particularly a failure to include treatment related deaths in the survival analysis. All but two studies were of less than 50 patients. Patients were excluded from some analyses for treatment related reasons. The exclusion of such patients undoubtedly altered the conclusions of the studies. Even if there was a survival advantage attributed to hydroxyurea, overall survival was somewhat poor. We found the evidence regarding the use of hydroxyurea and radiotherapy to be inadequate for assessing its role in the treatment of cervical cancer.

Survival and recurrence after concomitant chemotherapy and radiotherapy for cancer of the uterine cervix: a systematic review and meta-analysis

BACKGROUND

The US National Cancer Institute alert in February, 1999, stated that concomitant chemotherapy and radiotherapy should be considered for all patients with cervical cancer. Our aim was to review the effects of chemoradiotherapy on overall and progression-free survival, local and distant control, and acute and late toxicity in patients with cervical cancer.

METHODS

With the methodology of the Cochrane Collaboration, we did a systematic review of all known randomised controlled trials done between 1981 and 2000 (17 published, two unpublished) of chemoradiation for cervical cancer.

FINDINGS

The trials included 4580 randomised patients, and 2865-3611 patients (62-78%) were available for analysis. Cisplatin was the most common agent used. The findings suggest that chemoradiation improves overall survival (hazard ratio 0.71, p<0.0001), whether platinum was used (0.70, p<0.0001) or not (0.81, p=0.20). A greater beneficial effect was seen in trials that included a high proportion of stage I and II patients (p=0.009). An improvement in progression-free survival was also seen with chemoradiation (0.61, p<0.0001). Thus, the absolute benefit in progression-free and overall survival was 16% (95% CI 13-19) and 12% (8-16), respectively. A significant benefit of chemoradiation on both local (odds ratio 0.61, p<0.0001) and distant recurrence (0.57, p<0.0001) was also recorded. Grade 3 or 4 haematological (odds ratio 1.49-8.60) and gastrointestinal (2.22) toxicities were significantly greater in the concomitant chemoradiation group than the control group. There was insufficient data to establish whether late toxicity was increased in the concomitant chemoradiation group.

INTERPRETATION

Concomitant chemotherapy and radiotherapy improves overall and progression-free survival and reduces local and distant recurrence in selected patients with cervical cancer, which may give a cytotoxic and sensitisation effect.

Is there bias in the publication of individual patient data meta-analyses?

OBJECTIVE

There is increasing empirical evidence for the existence of bias in the publication of primary clinical research, with statistically significant results being published more readily, more quickly, and in higher impact journals. Meta-analysis of individual patient data (IPD) may represent a gold standard of "secondary" clinical research, giving the best possible summary of current evidence for a particular question, but publication of these may also be subject to bias. This study aimed to explore which factors might be associated with publication of IPD meta-analyses and to identify potential sources of bias.

METHODS

For all known IPD meta-analysis projects in cancer, the responsible investigator was surveyed by means of a questionnaire to determine descriptive characteristics of the meta-analysis, the nature of the results, and details of the publication history.

RESULTS

There is no good evidence that overall publication status of meta-analyses in cancer is dependent on the statistical or clinical significance of the results. However, those meta-analyses with nonsignificant results did seem to take longer to publish and were published in lower impact journals compared with those with more striking results.

CONCLUSIONS

Based on the current data, there seems to be no strong association between the results of IPD meta-analyses in cancer and publication.

Preoperative radiotherapy for esophageal carcinoma. Oeosphageal Cancer Collaborative Group

BACKGROUND

The existing randomized evidence has failed to conclusively demonstrate the benefit or otherwise of preoperative radiotherapy in treating patients with potentially resectable esophageal carcinoma.

OBJECTIVES

This meta-analysis aimed to assess whether there is benefit from adding radiotherapy prior to surgery and whether or not any pre-defined patient subgroups benefit more or less from preoperative radiotherapy

SEARCH STRATEGY

Medline and CancerLit searches were supplemented by information from trial registers and by hand searching relevant meeting proceedings and by discussion with relevant trialists, organisations and industry.

SELECTION CRITERIA

Trials were eligible for inclusion in this meta-analysis provided they randomized patients with potentially resectable carcinoma of the esophagus (of any histological type) to receive radiotherapy or no radiotherapy prior to surgery. Trials must have used a randomization method which precluded prior knowledge of treatment assignment and completed accrual by December 1993, to ensure sufficient follow-up by the time of the first analysis (September 1995).

DATA COLLECTION AND ANALYSIS

A quantitative meta-analysis using updated data from individual patients from all properly randomized trials (published or unpublished) comprising 1147 patients (971 deaths) from five randomized trials. This approach was used to assess whether preoperative radiotherapy improves overall survival and whether it is differentially effective in patients defined by age, sex and tumour location.

MAIN RESULTS

With a median follow-up of 9 years, in a group patients with mostly squamous carcinomas, the hazard ratio (HR) of 0.89 (95% CI 0.78-1.01) suggests an overall reduction in the risk of death of 11% and an absolute survival benefit of 3% at 2 years and 4% at 5 years. This result is not conventionally statistically significant (p=0.062). No clear differences in the size of the effect by sex, age or tumor location were apparent.

REVIEWER'S CONCLUSIONS

Based on existing trials, there was no clear evidence that preoperative radiotherapy improves the survival of patients with potentially resectable esophageal cancer. These results indicate that if such preoperative radiotherapy regimens do improve survival, then the effect is likely to be modest with an absolute improvement in survival of around 3 to 4%. Trials or a meta-analysis of around 2000 patients (90% power, 5% significance level) would be needed to reliably detect such an improvement (from 15 to 20%).

Can the published data tell us about the effectiveness of neoadjuvant chemotherapy for locally advanced cancer of the uterine cervix?

The effect of neoadjuvant chemotherapy on survival of patients with locally advanced cervical cancer was investigated by conducting a systematic review and meta-analysis of the published data. Of the 21 randomised trials that we identified, only 15 were published. Furthermore, 2-year survival data could be extracted from only seven trial reports and 3-year survival from only nine trial reports. Meta-analyses of the published data at 2 and 3 years are neither clearly in favour of neoadjuvant chemotherapy nor control (2 years: odds ratio (OR) = 1.09, 95% confidence interval (CI) = 0.83-1.45, P = 0.37; 3 years: OR = 0.96, 95% confidence interval (CI) = 0.73-1.25, P = 0.45). Being restricted to only some of the data from a relatively small fraction of the randomised trials, these analyses potentially suffer from a number of biases and are therefore inconclusive. The only reliable way to judge the value of neoadjuvant chemotherapy in this disease is to perform a meta-analysis of centrally collected, updated, individual data on all patients from all known randomised trials. Such an analysis is currently being carried out by an international collaborative group.

Preoperative radiotherapy in esophageal carcinoma: a meta-analysis using individual patient data (Oesophageal Cancer Collaborative Group)

PURPOSE

The existing randomized evidence has failed to conclusively demonstrate the benefit or otherwise of preoperative radiotherapy in treating patients with potentially resectable esophageal carcinoma. This meta-analysis aimed to assess whether there is benefit from adding radiotherapy prior to surgery.

METHODS AND MATERIALS

This quantitative meta-analysis included updated individual patient data from all properly randomized trials (published or unpublished) comprising 1147 patients (971 deaths) from five randomized trials.

RESULTS

With a median follow-up of 9 years, the hazard ratio (HR) of 0.89 (95% CI 0.78-1.01) suggests an overall reduction in the risk of death of 11% and an absolute survival benefit of 3% at 2 years and 4% at 5 years. This result is not conventionally statistically significant (p = 0.062). No clear differences in the size of the effect by sex, age, or tumor location were apparent.

CONCLUSION

Based on existing trials, there was no clear evidence that preoperative radiotherapy improves the survival of patients with potentially resectable esophageal cancer. These results indicate that if such preoperative radiotherapy regimens do improve survival, then the effect is likely to be modest with an absolute improvement in survival of around 3 to 4%. Trials or a meta-analysis of around 2000 patients would be needed to reliably detect such an improvement (15-->20%).

Adjuvant chemotherapy for soft-tissue sarcoma: review and meta-analysis of the published results of randomised clinical trials

Fifteen published randomised trials comparing adjuvant chemotherapy with no chemotherapy in soft-tissue sarcoma (STS) were identified (1546 patients). A qualitative review and a meta-analysis of this published literature were performed. With the qualitative review it was not possible to synthesise the apparently conflicting results of individual trials. The meta-analysis of the published data suggests an improvement in survival at 2 years (OR = 0.73, 95% CI = 0.53-0.99, P = 0.044) and at 5 years (OR = 0.59, 95% CI = 0.45-0.78, P = 0.0002) in favour of chemotherapy. However, the assumptions and approximations required to conduct this quantitative summary demand that the results are interpreted with caution. The only reliable means of assessing the current evidence on whether adjuvant chemotherapy has a role in the treatment of patients with STS, is to collect, check and reanalyse individual patients data (IPD) from each trial centrally, and formally combine the results in a stratified time-to-event analysis. Such an IPD analysis is currently being undertaken by an international collaborative group.

The tapeworm Schistocephalus solidus alters the activity and response, but not the predation susceptibility of infected copepods

Cyclops abyssorum and Cyclops scutifer were experimentally infected with procercoids of the cestode Schistocephalus solidus, then examined for altered behavior and susceptibility to predation, respectively. Infected C. abyssorum differed from uninfected controls in their initial response to disturbance and their degree of activity but only when they harbored procercoids that were potentially infective to the next host. To examine the possible consequence of the altered behavior for susceptibility to predation, three-spined sticklebacks (Gasterosteus aculeatus) were offered equal numbers of infected and uninfected C. scutifer. Infected copepods were not preyed upon significantly more than controls.

Correlation of autoantibody titres with central nervous system pathology in experimental African trypanosomiasis

CD-1 mice infected with the protozoan parasite Trypanosoma brucei brucei developed few signs of central nervous system pathology associated with the invasion of the central nervous system by these parasites and did not survive beyond 5-6 weeks with deaths common before this time point. However, use of the trypanocidal drug diminazene aceturate (40 mg/kg), which fails to cross the blood-brain barrier, on day 21 post-infection led to the development of central nervous system pathology similar to that seen in the fatal post-treatment reactive encephalopathies that can occur in human African trypanosomiasis. Enzyme-linked immunosorbent assays were used to measure autoantibody titres to double-stranded DNA, myelin basic protein and to the myelin-specific galactocerebrosides and gangliosides in groups of infected mice, with or without the post-treatment reaction, on day 30 post-infection and compared with uninfected controls. Infection with T. brucei brucei raised the titres of all of these autoantibodies. Treatment of infected mice with diminazene aceturate resulted in elevated levels of all of these autoantibodies compared to the untreated animals. There was a strong positive correlation between the central nervous system pathology and the levels of autoantibodies to myelin basic protein, galactocerebrosides and gangliosides, but not to double-stranded DNA. The elevated titres observed may be a consequence of the polyclonal B cell activation that is believed to occur in African trypanosomiasis, parasite epitopes that are cross-reactive with these central nervous system (CNS)-specific antigens or result from the CNS damage associated with sub-curative chemotherapy.

Infectivity of plerocercoids of Schistocephalus solidus (Cestoda: Ligulidae) and fecundity of the adults in an experimental definitive host, Gallus gallus

Aspects of the infectivity of the plerocercoid stage and the fecundity of the adult stage of Schistocephalus solidus were examined using the chicken, Gallus gallus, as an experimental host. To investigate size-related infectivity of the plerocercoid stage to a definitive host, a range of plerocercoids (166) were weighed, and each was fed to an individual male chicken. Only a very small percentage of plerocercoids weighing less than 50 mg established compared with in excess of 50% in all other weight classes. To examine the factors affecting the quantity of eggs produced by the adult stage, 15 similar-sized plerocercoids (160-218 mg) were fed to chickens. The majority of plerocercoids administered established as adults and survived until the experiment was terminated on day 7 postinfection (PI). Fecal egg counts indicated that all established worms commenced egg production on day 2 PI with peak output on day 2 or 3 PI. By day 7 PI, egg production in the surviving worms had declined, but it was still evident. The final weight of the adult and the average egg output per worm were unrelated to the initial weight of the infecting plerocercoid. However, the average egg output was predicted by the final adult dry weight and to a lesser extent by the proportion of weight lost in the transition from plerocercoid to adult, but not by the absolute weight loss.

Zymosan activation of plasma reduces hypoxic pulmonary vasoconstriction

Small doses of endotoxin (15 micrograms/kg IV) inhibit the pulmonary vascular pressor response to alveolar hypoxia in the anesthetized dog. One of the actions of endotoxin is to initiate the alternate pathway of complement activation. Incubation of human plasma with zymosan (ZAP) will activate this pathway. We wished to see if ZAP would mimic the effect of endotoxin. Prior to ZAP, hypoxia (F1O2 12%) in 5 anesthetized dogs increased pulmonary vascular resistance (PVR: mm Hg/L/min) from 3.7 +/- 0.8 to 7.1 +/- 1.5. After 50 ml ZAP IV the PVR change with hypoxia was only from 3.6 +/- 0.6 to 3.9 +/- 0.8. Plasma heated to destroy complement prior to ZAP incubation in one experiment did not reduce the pressor response. In a further 5 dogs pretreated with meclofenamate (2 mg/kg IV) the PVR increased from 3.7 +/- 0.4 to 7.5 +/- 0.4 with hypoxia prior to IV ZAP and from 4.4 +/- 0.5 to 6.5 +/- 0.6 after ZAP. The effect of ZAP indicates that endotoxin may work through the activation of complement. The protection of the hypoxic pressor response by meclofenamate suggests that the ZAP inhibition (like endotoxin inhibition) may involve dilator prostaglandin-like substances.